SEARCH RESULTS FOR: Inflammation

Myocardial Infarction: Findings on History

Yu Yan - MI Findings on History - FINAL.pptx - Myocardial Infarction: Findings on HistoryLegend:Published January 30, 2013 on www.thecalgaryguide.comMechanismPathophysiologySign/Symptom/Lab FindingComplicationsAuthor: Yan YuReviewers:Sean SpenceTristan JonesNanette Alvarez** MD at time of publication Systolic function(necrotic myocardium cannot contract as well)Reflexive ? in sympathetic activity (to try to maintain CO)Clammy skin? stroke volume (SV), ? cardiac output (CO)Myocardial infarction (tissue necrosis)Note: Myocardial ischemic pain may differ between patients, but recurrences usually feel the same in any given patient.Generalized vasoconstrictionVasoconstriction of skin arteriolesCool skinLocal myocardial inflammationIrritation of T1-T4 sympathetic afferentsIrritation of cardiac branches of vagus nerveSignals enter spinal cord, mixes with T1-T4 dermatomesCrushing, Diffuse L).(Onset: often at rest; crescendo)Activation of reflexive vagal responses (listed below)Weakness, dizziness, nausea, vomitingInflammatory mediators irritates nerves innervating the heart (the cardiac plexus)Cytokines act on hypothalamic T0 regulatorMild fever? Sweating (diaphoresis)Inflammatory cytokines can spread systemicallyBrain perceives nerve irritation as pain coming from T1-T4 dermatomesBlood backs up from the LV, into the left atrium and eventually accumulates in the pulmonary vasculatureHigh pulmonary venous blood pressure forces fluid out of capillaries, into pulmonary interstitium & alveoliRespiratory muscles work harder to ventilate lungsSoggier lung interstitium ? lung complianceDyspnea(Shortness of breath)Fluid compresses airways, ? resistance to airflow 102 kB / 204 words" title="Yu Yan - MI Findings on History - FINAL.pptx - Myocardial Infarction: Findings on HistoryLegend:Published January 30, 2013 on www.thecalgaryguide.comMechanismPathophysiologySign/Symptom/Lab FindingComplicationsAuthor: Yan YuReviewers:Sean SpenceTristan JonesNanette Alvarez** MD at time of publication Systolic function(necrotic myocardium cannot contract as well)Reflexive ? in sympathetic activity (to try to maintain CO)Clammy skin? stroke volume (SV), ? cardiac output (CO)Myocardial infarction (tissue necrosis)Note: Myocardial ischemic pain may differ between patients, but recurrences usually feel the same in any given patient.Generalized vasoconstrictionVasoconstriction of skin arteriolesCool skinLocal myocardial inflammationIrritation of T1-T4 sympathetic afferentsIrritation of cardiac branches of vagus nerveSignals enter spinal cord, mixes with T1-T4 dermatomesCrushing, Diffuse "Pain" or "tightness": Often retrosternal, with radiation to shoulder, neck, and inner aspect of both arms (R > L).(Onset: often at rest; crescendo)Activation of reflexive vagal responses (listed below)Weakness, dizziness, nausea, vomitingInflammatory mediators irritates nerves innervating the heart (the cardiac plexus)Cytokines act on hypothalamic T0 regulatorMild fever? Sweating (diaphoresis)Inflammatory cytokines can spread systemicallyBrain perceives nerve irritation as pain coming from T1-T4 dermatomesBlood backs up from the LV, into the left atrium and eventually accumulates in the pulmonary vasculatureHigh pulmonary venous blood pressure forces fluid out of capillaries, into pulmonary interstitium & alveoliRespiratory muscles work harder to ventilate lungsSoggier lung interstitium ? lung complianceDyspnea(Shortness of breath)Fluid compresses airways, ? resistance to airflow 102 kB / 204 words" />

myocardial-infarction-findings-on-investigations

Yu Yan - MI Findings on Investigations - FINAL.pptx Myocardial Infarction: Findings on InvestigationsAuthor: Yan YuReviewers:Sean SpenceTristan JonesNanette Alvarez** MD at time of publicationTissue ischemia disrupts normal cardiac electrical conduction(detected on serial ECG)Acute, trans-mural myocardial ischemiaIschemia of sub-endocardial myocardiumMyocardial infarctionNote: Both types of ST-segment changes are non-specific: they can indicate Myocardial Infarctions , but can also be false positives (i.e. caused by left ventricular hypertrophy, bundle branch blocks, and other non-myocardial ischemic causes)If ischemia progresses to tissue infarctionPathologic Q-waves (localizes to site of ischemia)Tissue necrosis ? Local myocardial inflammation2-4 hours after MI: troponin proteins released into blood3-8 hours after MI:Creatinine-kinase MB-isozymes released into blood? serum Cardiac Troponins: cTnT, cTnI(Sensitive and most specific serum marker for myocardial necrosis)Relatively faster clearance from circulation? serum CK-MB(less sensitive and specific for myocardial necrosis than Troponins)ST-segment depression(non-localizing)Inflammatory cytokines can spread systemicallyStimulation of neutrophil and monocyte migration towards area of inflammation? WBC count (on CBC)? C-Reactive Protein (CRP)Dead, damaged cardiac myocytes release inner contents into the bloodRelatively slower clearance from circulationSerum CK-MB levels normalize within 3 daysSerum Troponin levels normalize within 14 daysNote: Measuring both CK-MB and Troponins gives a timeline to the MI. For instance, if CK-MB is normal but Troponins are high, it means the MI happened >3 days but <14 days ago.ST-segment elevation(localizes to site of ischemia)Legend:Published January 30, 2013 on www.thecalgaryguide.comMechanismPathophysiologySign/Symptom/Lab FindingComplications 104 kB / 212 words

systemic-lupus-erythematosus-gastrointestinal-manifestations

Systemic Lupus Erythematosus: Gastrointestinal Manifestations Abbreviations: • APLA Phospholipid — Anti-Antibodies 1— Production of auto-antibodies APLA in circulation promotes blood coagulation —01• Thrombosis of vessels in the pancreas Micro-thrombi of vessels in the liver Liver infarcts Thrombosis of vessels in the small intestine Acute Pancreatitis Death of liver cells release contents into blood stream Thrombus in the hepatic vein • Vascular Damage Mesenteric Vasculitis/Ischemia Budd Chiari Syndrome Damage to Auerbach's Plexus 11` Liver Enzymes 1` in capillary permeability Abnormal release of inflammatory cytokines 1 Inflammation in esophageal muscles Protein-Losing Enteropathy Ascites Note: The gastrointestinal manifestations of systemic lupus erythematosus are due to multifactorial and complex causes, some of which are unknown. Legend: Pathophysiology Mechanism Impaired motor innervation Authors: Joseph Tropiano Reviewers: Zaini Sarwar Harjot Atwal Liam Martin* * MD at time of publication Abnormal production of immune complexes Immune complex deposition in blood vessels Immune complex deposition in smooth muscle Inflammatory reaction in the GI tract Immune complex mediated vasculitis Chronic ischemia of bowel smooth muscle Muscular damage Myopathy or neurogenic pathology of the GI muscles GI muscle damage not severe enough to inhibit peristalsis completely Esophageal Motility Disorders Dysphagia Sign/Symptom/Lab Finding Complications Hypomotility Dysmotility

esophageal-gastric-varices

Esophageal/Gastric Varices: Pathogenesis and clinical findings Schistosomiasis Schistosoma species enter the body through the skin and circulate to liver Eggs lodge in terminal portal venules causing inflammation and fibrosis • 1` resistance through fibrosed and inflamed sinusoids Cirrhosis Liver disease activates hepatic stellate cells causing hepatic fibrosis • I` resistance through fibrosed and distorted sinusoids • 1` portal inflow due to splanchnic vasodilation Veno-Occlusive Disease Budd-Chiari Syndrome Endothelial damage Hypercoagulable in the sinusoids leads to clotting states* cause factor deposition in thrombosis of hepatic sinusoids hepatic veins 1` resistance t resistance through through hepatic occluded distal veins occluded sinusoids by thrombus ► Intra Hepatic Portal Hypertension Post Hepatic Portal Portal Vein Thrombosis Hypercoagulable states* cause thrombosis of portal vein Infiltrative Lesion • Primary or secondary malignancy localized to the portal vein Splenic Vein Thrombosis Pancreatitis leads to inflammation and thrombosis of the splenic vein 1 resistance through '1' resistance through 1` resistance through portal vein occluded portal vein occluded by splenic vein occluded by thrombus malignancy by thrombus Pre Hepatic Portal Hypertension Hypertension *Hypercoagulable states such as thrombophilia, malignancy, or connective tissue disease Portal esophageal/gastric Esophageal/Gastric blood flow backed anastomoses up into Varices As variceal pressure 1` vessels swell 4— Blood loss from circulation 1 vessel J, wall thickness 1 vessel size tension Dilation of veins in submucosa Blood oxidized and vomited or passed through GI Authors: Bigger Varices Variceal rupture Upper GI bleed Gabriel Burke Reviewers: Vadim lablokov Laura Byford-Richardson Meredith Borman* * MD at time of publication • Red Wale Mark or Cherry Red Spot Blood loss too rapid to be oxidized before emesis or passage of GI (visualized on endoscopy) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications • Venous drainage of spleen backed up into gastric anastomoses Tachycardia and hypotension Anemia Death Melena Coffee ground emesis Hematemesis Bright red blood per rectum

central-retinal-artery-occlusion-pathogenesis-and-clinical-findings

Central Retinal Artery Occlusion: Pathogenesis and clinical findings Inflammatory Disease: Cardiogenic Embolism: Hypercoagulable state: Hematologic Disease: (i.e. GCA, SLE, GPA) (i.e. Valvular, arrhythmias, congenital defects) (i.e. OCP, Protein C&S deficiency, ATIII deficiency) (i.e. leukemia/lymphoma, sickle cell, polycythemia) Endothelial cell damage Abnormal blood flow 1` coagulation and/or 1 blood viscosity and creates hypercoagulable state causing localized stasis 4, anti-coagulation inflammation Abbreviations: • GCA — Giant Cell Arteritis • SLE — Systemic Lupus Erythematosus • GPA — granulomatosis with polyangitis • OCP — Oral contraceptive pill • ATIII — Anti-thrombin Ill Thrombus formation Blockage of central retinal artery Central Retinal Artery Occlusion (CRAO) Authors: Graeme Prosperi-Porta Reviewers: Stephanie Cote Usama Malik Johnathan Wong* * MD at time of publication Carotid Artery Atherosclerosis Atherosclerotic plaque dislodges from carotid artery The retina becomes pale 4, perfusion of retinal Slow retinal artery blood Acute retinal edema Ganglion cells and axons from NI, perfusion arterioles due to upstream flow allows for caused by ischemia results death due to ischemia CRAO segmentation of the blood column in a blurred appearance of the retina results in disc pallor seen months after CRAO The choroidal vessels supplying the macula via the posterior ciliary artery become more prominent within a background of retinal pallor

infectious-esophagitis-pathogenesis-and-clinical-findings

Infectious Esophagitis: Pathogenesis and clinical findings HIV/AIDS Radiation therapy Chemotherapy Organ Transplant Antibiotics I/Esophageal motility Tir CD4+ T cells 4,Monocyte and Corticosteroid and granulocyte precursors anti-TNF therapy • • Immunosuppression Note: Bacterial causes of infectious esophagitis are difficult to isolate as they are often polymicrobial in nature and derived from normal oral flora. Cytomegalovirus Infection of endothelial cells and fibroblasts I, Protective flora 4, Pathogen clearance Authors: David Deng Reviewers: Peter Bishay Vadim lablokov Kirles Bishay* MD at time of publication Mechanical stricture Inflammation Ulceration ,..,4 Dysphagia Infectious Viral Bacterial infection infection esophagitis • Fungal infection Odynophagia (i.e. Candida) Herpes Simplex Infection of squamous cells and macrophages Colonization facilitated by use of antacid therapy Nuclear Large Superficial Squamous Macrophage inclusion bodies esophageal ulceration ulcers cell inclusion bodies aggregation Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Spores and pseudohyphae seen on biopsy • Invas.on of underlying blood vessels • White plaques over erythematous base '1' neutrophils due to inflammatory response

Primary Spontaneous Pneumothorax: Pathogenesis and clinical findings

Primary Spontaneous Pneumothorax: Pathogenesis and clinical findings Thoracic Tall, thin endometriosis males Genetic Factors (i.e. FLCN mutations, HCY, MFS, CTD) Malnutrition Smoking Structurally compromised lung parenchyma Notes: • PSPs usually occur at rest • Respiratory symptoms vary in severity • Suspect thoracic endometriosis in young women with recurrent PSPs that coincide with menstruation • *Pathophysiology of tension pneumothorax is described in a separate slide Air leaks into the subcutaneous tissue Subcutaneous emphysema Authors: Lauren Hampton Reviewers: Kening (Midas) Kang Natalie Morgunov Sadie Kutz Usama Malik Leila Barss* * MD at time of publication Thoracic Ischemia endometriosis Mechanical forces of respiration create blebs Inflammation disrupts mesotheial and/or bullae ~ cell layer of the visceral pleura 47 Spontaneous rupture of blebs or bullae 47 Sudden onset pleuritic chest pain 71r Primary spontaneous pneumothorax: Presence or introduction of air in the pleural space in a patient WITHOUT diagnosed or clinically apparent lung disease Tachycardia Abbreviations: Communication occurs between the alveoli and pleural space • FLCN- Folliculin gene • HCY- Homocystinuria • MFS- Marfan syndrome Alveolar pressure > pleural pressure • CTD- Connective tissue disease • PSP- Primary spontaneous Air from the lungs enters the pleural space pneumothorax • V/Q- ventilation/perfusion Air separates the chest from /1` intrapleural pressure • Sp02- oxygen saturation the lung parenchyma Small areas of lung collapse Blood flow to areas of On affected side: under un-opposed intrinsic atelectasis is maintained -• Si, chest wall expansion elastic recoil while ventilation 4, t resonance to percussion Si, or absent tactile fremitus Si, or absent breath sounds 4, lung compliance Shunting and V/Q mismatch Pleural line on chest x-ray 1` work of breathing Tension pneumothorax* Accessory muscle use, 4• Sp02, Sudden onset dyspnea, Tachycardia Hypotension, Juglar venous Tachypnea distension, Pulsus paradoxus

Asthma Acute Exacerbation: Pathogenesis and Treatment

Asthma Acute Exacerbation: Pathogenesis and Treatment Viral URI Allergen Pollution Other Triggers Activation of immune system: Epithelial chemokine activation, lymphocyte activation, macrophage activation, t leukotriene production Inflammation of lower airway • Dyspnea Air flows past inflamed airways causes t irritation Cough and wheezing Release of inflammatory mediators Mucosal edema causing turbulent air flow 7Ir Wheezing Notes • Asthma: Airway hyper-responsiveness causing airflow obstructions • Acute Exacerbation (Asthma): An episode of increased symptoms due to decreases in airflow Abbreviations • PCO2: Partial pressure of CO, in arterial blood • PEF: Peak expiratory flow • SABA: Short-acting beta-2 agonists • Sp02 : Blood oxygen saturation level Mild to moderate exacerbation: PEF 50% of predicted Titrate O2 toSpO2, 92%, give SABA & steroids ■ Good response: symptoms resolved, PEF > 80% [Treat at home with SABA as needed and steroids Dyspnea Bronchoconstriction 1` Residual volume and 1` PCO2 Respiratory failure 1` Air trapping causes '1' intra-alveolar pressure Severe exacerbation: PEF 50% of predicted Educate patient regarding medications, Loss of Pulsus inhaler technique & [consciousness paradoxus follow up with primary care provider I Legend: Pathophysiology Mechanism Titrate O2 to402 93%, give SABA, steroids & magnesium sulfate Sign/Symptom/Lab Finding {Worsening symptoms and/or respiratory failure: Do not delay intubation, send to ICU, give SABA, steroids & magnesium sulfate Authors: Luke Gagnon Reviewers: Midas (Kening) Kang Usama Malik Lian Szabo* * MD at time of publication 4, Delivery of oxygen rich air to alveoli 4, Oxygenation of blood Drowsy and confused Central cyanosis • Tachycardia Pneumothorax [Depending on 1 severity: Observation or place chest tube

Bronchiectasis Pathogenesis and clinical findings

Bronchiectasis: Pathogenesis and clinical findings Acquired immunodeficiency Lymphoma, HIV, transplant Autoimmune Lupus, inflammatory bowel disease, rheumatoid arthritis Congenital/Genetic Cystic fibrosis, A1AT deficiency, Marfan, immunoglobulin deficiency, Kartagener syndrome, Young syndrome Endobronchial obstruction Neoplasm, foreign body, lymph node compression Other Inhalation exposure (smoke, ammonia), MAC complex infection, COPD, allergic bronchopulmonary aspergillosis, chronic infections Irreversibly dilated bronchi Chronic bronchial infection and inflammation 1 Easily collapsible airways I Bronchiectasis (persistent and progressive damage to lungs) Chronic cough (mucopurulent) Defect in immunity and/or mucus clearance Persistent bacteria in airway (commonly Pseudomonas/Staph aureus) Inflammatory response Rhinosinusitis Abbreviations: • A1AT — Alpha-1-antitrypsin • COPD — Chronic Obstructive Pulmonary Disease • HIV — Human Immunodeficiency Virus • MAC — Membrane Attack Complex • VQ— Ventilation/Perfusion ratio Legend: Pathophysiology Mechanism Fever Sign/Symptom/Lab Finding Failure to thrive (children) Authors: Rebecca (Becky) Phillips Reviewers: Midas (Kening) Kang Usama Malik Eric Leung* * MD at time of publication Notes: • Can be focal (single lobe/segment) or diffuse (both lungs) • Mainly in elderly • 1% prevalence in children Tissue damage Epithelial destruction of airways Further impairment of bacterial clearance Persistent inspiratory adventitious sounds (crackles > wheezing) Complications Structural damage to bronchial walls Obstructive pulmonary function tests Hemoptysis Chest pain VQ mismatch and 4, gas exchange 4, oxygenation Digital clubbing (rare) Fatigue Dyspnea Cyanosis (uncommon)

Benign Prostatic Hyperplasia: Pathogenesis and medications

Benign Prostatic Hyperplasia: Pathogenesis and medications Aging Testosterone Testosterone metabolized into DHT by type II 5- a-reductase in prostate DHT binds to androgen receptor in prostate cell nuclei Hyperplasia of the prostate Prostate encapsulated by fibromuscular tissue, therefore grows inwards Prostatic urethral compression and bladder outlet obstruction Legend: a-1 blockers (e.g. tamsulosin) Note: MoA not fully established PDE-5 inhibitors (e.g. tadalafil) Bladder and prostate smooth-muscle a-1 receptor antagonism —110. Relaxation of bladder outlet and prostate smooth-muscle Authors: Michael Korostensky Reviewers: Alex Tang Usama Malik Dr. Jay Lee* * MD at time of publication Acronyms: 5-ARI = 5-a reductase inhibitors COX = cyclooxygenase DHT = dihydrotestosterone GnRH = gonadotropin-releasing hormone LUTS = lower urinary tract symptoms PDE-5-mediated cGMP degradation in prostate smooth-Improved urinary outflow muscle and associated vascular supply Relaxation of prostate smooth-muscle MoA = mechanism of action NSAID = nonsteroidal anti-inflammatory drugs PDE-5 = phosphodiesterase-5 -NO 5-ARIs (e.g. dutasteride) LHRH receptor antagonists (e.g. cetrorel ix) P3-adrenergic agonists (e.g. mirabegron) anticholinergics (e.g. oxybutynin) NSAIDs 1` Bladder pressures Pathophysiology Mechanism 5-a-reductase activity 1, Conversion of testosterone into DHT 4, Progression of LUTS 1, Testosterone secretion from testicular Leydig cells 1, LH secretion from pituitary GnRH antagonism DHT production Relaxation of detrusor Bladder muscle 1` capacity Improved LUTS Acetylcholine antagonism at muscarinic receptors Relaxation of bladder outlet smooth-muscle 1` volume to first detrusor contraction 4, Prostaglandin release Analgesia and 4, Prostatic ,f, COX activity ► inflammation —110. Bladder smooth-muscle hyperplasia (detrusor thickening) /1` Sensitivity (i.e. overactive detrusor) -1110. 1, Volume to first detrusor contraction LUTS

Mixed Urinary Incontinence Pathogenesis and clinical findings

Mixed Urinary Incontinence: Pathogenesis and clinical findings Abbreviations: • BOO — Bladder Outlet Obstruction • BPH — Benign Prostatic Hyperplasia • CNS — Central Nervous System • IAP — Intra-abdominal pressure • OAB — Over-Active Bladder • PVR — Post Void Residual • SUI —Stress Urinary Incontinence • UTI — Urinary Tract Infection • UUI — Urge Urinary Incontinence Mixed Urinary Incontinence 47 Urinary leakage accompanied by both urgency and t intra-abdominal pressure Urgency Urinary Incontinence (UUI) 4, Urinary leakage preceded by a sudden, strong urge to void Overflow Incontinence vir Overfilling of the bladder from obstruction; BOO (tumour, stone, BPH, urethral or bladder neck stricture) Detrusor Overactivity Ilr OAB (idiopathic), CNS lesion (neurogenic), inflammation/ infection (cystitis, UTI), diabetes mellitus 4. Bladder Wall Compliance Progressive t in intravesicle pressure during bladder filling pushing urine from the bladder Authors: Braden Millan Reviewers: Alex Tang Usama Malik Jay C. Lee* * MD at time of publication Stress Urinary Incontinence (SUI) + Episodic involuntary urinary leakage with sudden l• in intra-abdominal pressure 4. Urethral hypermobility, intrinsic sphincter deficiency, or a poorly coapting urethra 4, 4, Pelvic floor muscle and ligament strength causing 4. tone of vesicoureteral sphincter unit; 4, urethral strength and associated striated and smooth muscle; iatrogenic Legend: Failure to Void Weak Stream (+ dribbling), Intermittent, Straining, '1` PVR if a complication of urinary retention; obstruction visible on cystoscopy Failure to Store Frequency, Urgency, Nocturia, Dysuria if SUI or UUI not caused by obstruction Pathophysiology Mechanism Urodynamic Studies SUI — 4, urethral closure pressure with 11` IAP/Bladder Volume and urinary leakage UUI — involuntary detrusor contraction and/or detrusor sphincter dyssynergia Incontinence, 4, Quality of Life, UTI's

Celiac Disease: Pathogenesis and clinical findings

Celiac Disease: Pathogenesis and clinical findings Associated with other autoimmune disorders (i.e. DM1, thyroiditis, RA, SLE, Addison's) Genetic predisposition -■ (Northern European, Down's syndrome, Associated with HLA DQ 2,8) Note: *The anti-TTG antibody is an IgA anti-body, therefore if the patient is IgA-deficient, absence of anti-TTG does not rule out celiac Anti-TTG in serum* Anti-TTG reacts with TTG in skin Deposition of anti-TTG in renal glomeruli Dermatitis herpetiformis Chronic Kidney Disease Small Bowel Biopsy: Crypts of bowel become enlarged (hyperplasia) with architectural change, villous shortening Legend: Pathophysiology Mechanism Exposure to prolamins (proteins found in wheat, rye, oats, barley) TTG alters prolamin Altered protein fits more easily into HLA HLA activates adaptive immunity IgA generated against prolamin-TTG Wheat prolamin (gliandin) interacts with and activates zonulin signalling Gut epithelium becomes more porous Large dietary proteins in epithelium disrupt tight junctions Author: Matthew Harding Yan Yu Peter Bishay Reviewers: Dean Percy Jason Baserman Usama Malik Kerri Novak* * MD at time of publication Inflammation of Intestinal epithelium Inflammation disrupts structure of bowel mucosa Mechanism Unknown Lymphocytes migrate to site of inflammation Extraintestinal Complications: Arthropathy Ataxia (gluten associated) Infertility Mild Hepatitis Villi of intestine atrophy Risk of Microscopic Colitis (50x) Malabsorption Extraintestinal manifestations: Chronic watery Fatigue Failure to thrive, weight loss Anemia (Fe, B12, folate) Peripheral neuropathy (B12, Ca) Ataxia (Ca) Dysrhythmia (Ca, K) Osteoporosis (Vit D, Ca) diarrhea + Intestinal manifestations steatorrhea: Pale, foul-smelling Abdominal bloating Steatorrhea (fat in stool) Diarrhea

Orbital Cellulitis: Pathogenesis and clinical findings

Orbital Cellulitis: Pathogenesis and clinical findings Authors: Amanda Marchak Reviewers: Jaimie Bird Dr. Rupesh Chawla* * MD at time of publication Staphylococcus aureus, Streptococcus pyogenes Note: Orbital cellulitis is an extremely serious infection. If not caught and treated early, it can lead to death. CT should be performed if suspected. Involves the orbit Panopthalmitisb Endopthalmitisc Blindness Streptococcus pneumoniae, Moraxella catarrhalis, Haemophilus influenza Local infection or break in skin Eye surgery or trauma Direct inoculation Sinusitis (more common) Periorbital cellulitis1,2 Hematogenous spread Contiguous spread of infection Pathogens reach orbital tissue (posterior to the orbital septum) Spreads to periorbital tissue (anterior to the orbital septum) Localized inflammation Conjunctival chemosisa Eyelid and periorbital edema Pain on palpation Induration Warmth Orbital Cellulitis Inflammation of orbital tissue Proptosis Spreads to surrounding structures Subperiosteal abscess Brain abscess Cavernous sinus thrombosis Meningitis Subdural empyema Orbital abscess Notes: Impinges on ocular muscles Impaired extra- ocular movements Pain with eye movement or opthalmoplegia Definitions: Impinges on nerves Afferent pupillary defect Decreased visual acuity Exposes cornea Corneal drying and scarring a. Chemosis: Edema of the bulbar conjunctiva b. Panopthalmitis: inflammation of all coats of the eye including intraocular structures. c. Endopthalmitis: inflammation of the interior of the eye. 1. See slide on Periorbital Cellulitis for how sinusitis can lead to the development of periorbital cellulitis 2. The micro-organism responsible for periorbital cellulitis varies depending on how the pathogen was introduced to the system. Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 5, 2018 on www.thecalgaryguide.com

Periorbital Cellulitis: Pathogenesis and Clinical Findings

Periorbital Cellulitis: Pathogenesis and Clinical Findings Authors: Amanda Marchak Reviewers: Jaimie Bird Dr. Rupesh Chawla* * MD at time of publication Staphylococcus aureus, Streptococcus pyogenes (most common organisms) Note: Also referred to as preseptal cellulitis Dacryoadenitisa Conjunctivitisb Acute chalazionc Dacryocystitisd Hordeolume Streptococcus pneumoniae, Moraxella catarrhalis, non-typable Haemophilus influenza (most common organisms) Abrasion Insect bite Burns Trauma Local infection Contiguous spread of infection Sinusitis Otitis media Hematogenous spread Local break in skin Micro-organisms enter Definitions: Note: Eye exam should reveal normal: - extra-ocular movements and globe position - pupillary reflex and visual acuity If any are abnormal, the presentation is no longer considered periorbital cellulitis, as the infection has likely spread beyond the preseptal compartment/orbital septum. If the eye cannot be assessed, the patient NEEDS a CT scan. Pathogens reach dermis and subcutaneous periorbital tissue Periorbital Cellulitis a. Dacryoadenitis: infection of the lacrimal glands b. Conjunctivitis: inflammation of the conjunctiva c. Chalazion: a benign, painless bump or nodule inside the upper or lower eyelid which results from healed internal hordeolums that are no longer infectious. d. Dacryocystitis: an infection of the lacrimal sac, secondary to obstruction of the nasolacrimal duct at the junction of lacrimal sac. e. Hordeolum: localized infection or inflammation of the eyelid margin involving hair follicles of the eyelashes or meibomian glands. Spreads beyond preseptal compartment/orbital septum Involves the orbit Orbital cellulitis See slide on Orbital Cellulitis: Pathogenesis and clinical findings Localized inflammation Pain on palpation Induration Warmth Eyelid and periorbital edema Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 5, 2018 on www.thecalgaryguide.com

Mastoiditis: Pathogenesis and clinical findings

Mastoiditis: Pathogenesis and clinical findings Authors: Amanda Marchak Reviewers: Nicola Adderley Jim Rogers Emily Ryznar Danielle Nelson* * MD at time of publication Acute Otitis Media (AOM) Distal middle ear is physically connected to mastoid air spaces Pathogens spread from middle ear to the mastoid air spaces Mucosa lining the mastoid becomes inflamed Mastoiditis 1 Infection persists Accumulation of pus in mastoid cavities ↑ pressure Formation of abscess cavities Dissection of pus into adjacent areas Infection spreads Into intracranial compartment See slide on Acute Otitis Media (AOM): Pathogenesis and Clinical Findings in Children Post- operation Trauma Infection Notes: 1. Most common suppurative complication of AOM Tenderness, erythema, swelling and fluctuance over the mastoid process Inflammation spreads to external auditory canal Cranial Nerve VII anatomically near mastoid Cranial Nerve VIII anatomically near mastoid air space Destroys bony septae b/t air cells (visible on CT) Mastoid abscess Swelling of external auditory canal Mastoid inflammation disrupts nerve Mastoid inflammation disrupts nerve Petrositis Facial nerve palsy Sensorineural hearing loss Labyrinthitis Osteomyelitis of the calvaria Into adjacent bones Underneath the periosteum Subperiosteal abscess Pinna is pushed out and of the temporal bone Into the neck beneath the attachment of the sternocleidomastoid and digastric muscles forward Dural venous thrombosis Temporal lobe abscess Meningitis Epidural abscess Subdural abscess Cerebellar abscess Bezold abscess Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 5, 2018 on www.thecalgaryguide.com

Sinusitis: Pathogenesis and clinical findings

Sinusitis: Pathogenesis and clinical findings Authors: Amanda Marchak Reviewers: Nicola Adderley Jim Rogers Danielle Nelson* * MD at time of publication Abbreviations URTI – Upper respiratory tract infection Nasal obstruction/ congestion Hyposmia Headache Facial pain/pressure Maxillary tooth pain Ear pain/ fullness Osteomyelitis of frontal bone Chemical irritants Cystic Fibrosis Direct toxic effect on cilia Viral URTI Allergies Inflammation of paranasal sinuses Edematous passageways Septal deviation Adenoid hypertrophy Polyps Turbinate hypertrophy Tumors Foreign body Dysfunctional cilia Congenital and/or craniofacial abnormality Obstruct sinus ostia Cilia unable to clear mucus from sinuses Mucus unable to drain through ostia Post-nasal drip Mucus overflows from the sinuses Cough Mucus accumulates in sinuses Occupies a larger volume Applies ↑ pressure to sinus walls Mucopurulent discharge Bacterial1 overgrowth in sinuses Bacterial infection spreads to adjacent structures Halitosis Pharyngitis Throat clearing Dental root infection Immunodeficiency Note: Irritates the back of the throat Perforation of the Schneiderian membrane2 Passage of bacteria into the sinuses Fever Fatigue Subperiosteal orbital abscess Orbital abscess Orbital edema ↑ susceptibility to bacteria 1. The most common bacteria are Streptococcus pneumoniae, Haemophilus influenza, and Moraxella catarrhalis. Staphylococcus aureus and Group A Streptococcus may be seen, but are less common. However, in cases of dental root infection, oral anaerobes become more common, while Pseudomonas species are associated with foreign bodies. 2. The Schneiderian membrane is the membranous lining of the maxillary cavity. Cavernous sinus thrombosis Meningitis Cerebral abscess Subdural abscess Epidural abscess Periorbital or orbital cellulitis Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 5, 2018 on www.thecalgaryguide.com

Boutonniere Deformity: Pathogenesis and Complications

Boutonniere Deformity: Pathogenesis and Complications Laceration of extensor surface of PIP Authors: William F Hill Marshall Thibedeau Reviewers: Emily Ryznar Brett Byers* *MD at time of publication Rheumatoid Arthritis Hand trauma Hyperflexion of PIP Dislocation of PIP Central Slip Rupture Unopposed lumbrical and interossei pull on lateral bands Stretching of triangular ligament Volar subluxation of lateral bands Lateral band contraction Hyperextension of DIP Erosion of connective tissue Synovial inflammation Avulsion of central slip insertion Triangular ligament prevent bowstringing of the lateral bands during finger flexion EDC inserts dorsally on to extensor aponeurosis Interossei and lumbricals travel from volar aspect of palm with action dorsal to the axis of rotation Aponeurosis gives rise to central slip and lateral bands Elson test for central slip rupture: • Flexion of PIP 90 degrees over edge of table • Extend affected phalanx against resistance • Positive if DIP becomes extended and rigid • From exaggerated lateral band action Abbreviations: PIP proximal interphalangeal joint EDC: extensor digitorum communis IPJ: interphalangeal joint DIP: distal interphalangeal joint ROM: range of motion Flexion of PIP Boutonniere Deformity Shortening of collateral ligaments and volar plate of PIP joint Premanent contracture and fibrosis of IPJs Permanent deformity ↓ ROM in PIP extension Osteoarthritis Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published December 4, 2018 on www.thecalgaryguide.com

Complex Regional Pain Syndrome: Pathogenesis and clinical findings

Complex Regional Pain Syndrome: Pathogenesis and clinical findings Authors: Calvin Howard Reviewers: Sina Marzoughi Scott Jarvis* * MD at time of publication Central nervous system lesion Unknown Mechanism ACE inhibitors Trauma with at most minor nerve lesion i.e. surgery, nerve compression, fracture, tissue trauma, ischemia, sprain Neurogenic inflammation Sympathetic dysregulation Acute Phase Proinflammatory cytokine profile Central and peripheral nociceptive sensitization Chronic Phase Central sensorimotor dysregulation ↓ Perfusion of cortex & ↓ cortical grey matter volume of limbic and sensorimotor areas ↑ Perfusion to motor cortex ↓ Grey matter volume in cortical pain regions ↓ Connectivity of sensorimotor planning/control regions Complex Regional Pain Syndrome 1 (Formerly Reflex Sympathetic Dystrophy) Sensory: Hyperalgesia or allodynia Sudomotor: Edema, sweating changes, asymmetric sweating Vasomotor: Temperature asymmetry, altered skin colour Motor/trophic: Decreased range of motion, motor dysfunction, trophic changes Definitions: • Hyperalgesia: Heightened sensation of pain • Allodynia: Pain caused by normally non-painful stimuli • Sudomotor: Relating to the sweat glands • Vasomotor: Relating to the muscle within vasculature • Trophic: Relating to growth and atrophy of cells • Cytokine: Molecules that recruit inflammatory cells Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published September 20, 2018 on www.thecalgaryguide.com

Venous insufficiency- Signs and symptoms

Venous insufficiency- Signs and symptoms vein veins blood flow interruption venous system valve incompetence reflux venous obstruction venous return backflow blood hypertension hydrostatic transmural pressure in postcapillary vessels capillary dilatation vessel permeability extravasation RBCs interstitial hemoglobin released degraded hemosiderin deposits hemosiderosis brown discolouration high pressure superficial venous circulation varicose veins tortuous dilated superficial veins distended veins compress somatic nerves achy pain protein-rich exudate edema peripheral ankle edema tissue perfusion metabolic exchange stasis dermatitis dermal fibrosis lipodermatosclerosis fibrotic thickened skin pruritus chronic inflammation risk of thrombus local ischemia embolus skin integrity venous ulcer risk of infection Adderley gagnon Waechter

Reactive Neutrophilia- Pathogenesis and Clinical Findings

reactive neutrophilic pathogenesis clinical findings infection inflammation malignancy drugs emotional stimuli stress smoking hyposplenism asplenia rheumatoid arthritis Crohn's epinephrine retinoic acid glucocorticoids anxiety exercise heat stroke surgery neutrophils neutrophil bone marrow demarginalization splenic sequestration neutrophilic ANC peripheral blood smear absolute neutrophil count left shift bands metamyelocytes myelocytes toxic granulations dohle bodies brenneis Siddique savoie ryznar

Primary Myelofibrosis pathogenesis and clinical findings

Primary Myelofibrosis: Pathogenesis and clinical findings Legend: Published March 30, 2019 on www.Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications thecalgaryguide.com Author: Tony Gu Reviewers: Naman Siddique Sonia Cerquozzi* Man-Chiu Poon* * MD at time of publication Definitions: Constitutive activation – Constant expression of gene Extramedullary hematopoeisis – red blood cell production outside of bone marrow Somatic mutations in genes that drive cancerous replication (e.g., JAK2, CALR, MPL) within hematopoietic stem cells Non-driver mutations in other myeloid genes (e.g., LNK, CBL, TET2, ASXL1, IDH) Constitutive activation of cellular proliferation pathways ↑ cell signaling ↑ gene transcription and expression Cellular proliferation and resistance to apoptosis Proliferation of abnormal megakaryocytes ↑ neutrophil engulfment by megakaryocytes ↑ growth factor release by megakaryocytes Stimulation of fibroblasts Stimulation of endothelial cells New blood vessel formation ↑ osteoprotegerin Unbalanced osteoblast proliferation Osteosclerosis Fibrosis of the bone marrow Anemia Bleeding and bruising Infections Fatigue and pallor Bone pain Increased cell turnover Tumor lysis syndrome Cachexia, night sweats, fever/chills, malaise Expanding marrow pushing against bone Extramedullary hematopoiesis Hepatomegaly Portal hypertension Splenomegaly ↑ LDH Thrombocytosis Leukocytosis Secretion of coagulation inducing cytokines Arterial and venous thromboembolism ↓ blood cell production & leukoerythroblastosis Thrombocytopenia Leukopenia ↑ K+, PO4 2-, uric acid ↓ Ca2+ Bone pain Periostitis Immature granulocyte and erythroid precursors with blasts ↑ cytokine production (+) ↑ sequestration of blood cells Disseminated intervascular coagulation (see MAHA slide) Definitions: Periostitis – Inflammation of the membrane surrounding bone Osteosclerosis – Abnormal hardening and increased in density of bone

Hemorrhoids - Pathogenesis and Clinical Findings

INTERNAL Hemorrhoids - Found proximal to the dentate line - Visceral innervation Behavioural or Genetic Predisposition I.e. hereditary bowel/rectal problems or shared habits and practices (unclear mechanism) Increased Intra-Abdominal Pressure I.e. pregnancy, constipation, chronic straining, lifting, cirrhosis Hemorrhoids: Pathogenesis and clinical findings Dilations originate from inferior hemorrhoidal venous plexus Vascular cushions engorge along anal canal Legend: Published March 30, 2019 on www.Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications thecalgaryguide.com Authors: Aleeza Manucot Reviewers: Yoyo Chan Sean Doherty Dr. Sylvain Coderre* * MD at time of publication Supporting tissues of anal cushions weaken, disintegrate, or deteriorate Inflammatory reaction occurs, involving vascular wall and connective tissue Thrombosis Pain ↑ mucus secretions or fecal soiling of prolapsing hemorrhoids Cushion epithelium erodes via damage from compression Painless rectal bleeding Bleeding without prolapse Prolapse with spontaneous reduction Prolapse requiring manual reduction Irreducible 1st degree 2nd degree 3rd degree 4th degree Infarction and thrombosis Acute severe pain Anal cushions prolapse (downwardly slide) into rectum or open space Dentate line: divides the upper two thirds and lower third of the anal canal EXTERNAL Hemorrhoids - Found distal to the dentate line - Somatic innervation Somatic nerve receptors activated Sebaceous glands ↑ secretions around area of hemorrhoid Itching Perianal irritation Swelling Inflammation creates prothrombotic state Hemorrhoids

gastroesophageal-reflux-disease-gerd-complications

Gastroesophageal Reflux Disease (GERD): Complications Esophageal stricture disease Esophagitis Esophageal adenocarcinoma Barrett’s esophagus GERD Reflux of gastric content into distal esophagus Damage to squamous esophageal epithelium Legend: Published March 30, 2019 on www.Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications thecalgaryguide.com Authors: Wendy Wang Reviewers: Yoyo Chan Sean Doherty Dr. Sylvain Coderre* * MD at time of publication Squamous esophageal epithelium undergoes metaplasia to become columnar epithelium This predisposes cells to premalignant changes (dysplasia) Collagen is deposited where ulcers heal Asthma/Chronic Cough Chronic Laryngitis Laryngeal and Tracheal Stenosis Extra-esophageal Complications Esophageal Complications Airway becomes irritated Fibroblasts proliferate and deposit granulation tissue in airway Tissue deposition leads to narrowing of laryngeal and tracheal space Damage to pharyngeal lining and airway Esophageal tissue repeatedly exposed to stomach acid Pro-inflammatory cells and cytokines are recruited to the area Definitions: • Metaplasia: abnormal change in the nature of a tissue • Pro-inflammatory cells and cytokines: Mediators of inflammation. Examples of cells include macrophages and T cells, cytokines include IL-17, IL-2, IL-4 Over time, collagen fibers contract Bronchoconstriction ↑ vagal tone ↑ bronchial reactivity Cough sensory nerve endings are stimulated Vagal reflex is activated Activation of cough center in brainstem ↑ inflammation of squamous epithelium Ulcers form in esophagus

Polyarteritis Nodosa (PAN): Pathogenesis and Clinical Findings

Polyarteritis Nodosa (PAN): Pathogenesis and clinical findings Environmental triggers Infectious/viral agents (commonly Hepatitis B) Medical Comorbidities Malignancies (most commonly hairy-cell leukemia) Immunogenetic Predisposition: patient is genetically predisposed to a dysregulated immune response Fever ↑ ESR and CRP Postulate 1 Viral antigen-antibody complexes deposit in vasculature, causing lesions and activating cellular inflammatory response Authors: Nela Cosic, Yan Yu* Reviewers: Sean Doherty Martin Atkinson* * MD at time of publication Palpable or necrotic purpura Malignant Hypertension Renal Insufficiency Myocardial ischemia Heart failure Diffuse myalgias Postulate 2 Viral replication causes direct injury to vascular endothelial cells ↑ Anti- endothelial cell autoantibodies (AECA) Altered cytokine profile (↑TNF-α, IL-1β, IFN-α, IL- 2)à↑ T-cell mediated immune response Weight metabolism Loss Autoimmune attack on various areas of the body Malaise and/or Arthralgias (knees, ankles, elbows, wrists) Orchitis: Testicular pain, erythema and/or swelling Small intestine perforation GI Manifestations Non-specific abdo pain GI hemorrhage Peripheral sensory changes: Distal mononeuropathy multiplex Polyarteritis Nodosa (PAN) Focal segmental necrotizing leukocytoclastic vasculitis of medium or small-sized arteries Inflammation of arteries damages the vascular endothelium of those arteries Inflammation predisposes formation of arterial thromboses Blockage of arteriesà tissue ischemia and possible necrosis (tissue cell death) ↑ basal Arterial aneurysms Inflamed subcutaneous arteries Inflamed renal artery àluminal narrowing and reduced blood flow to kidneys Inflamed coronary artery à luminal narrowing, occlusion, thromboses Segmental inflammation of muscular arteries, stimulating surrounding nociceptors. Muscle ischemia develops long-term. Ischemia/necrosis of the testicles Ischemia/necrosis of the small intestine Ischemic vasculitic nerve damage: Immune complex deposition within vessel walls of arteries traveling with nerves leads to persistent vascular inflammation and ischemia of associated nerve Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published April 18, 2019 on www.thecalgaryguide.com

dermatomyositis-dm-and-polymyositis-pm-pathogenesis-and-clinical-findings

Dermatomyositis (DM) and Polymyositis (PM): Authors: Merna Adly, Yan Yu* Reviewers: Nela Cosic Sean Doherty Martin Atkinson* * MD at time of publication Pathogenesis and clinical findings Immunogenetic and Cellular Predisposition Genetic polymorphisms cause dysregulated immune response, cytokine profile, and protein expression in muscle cells Demographics F:M, 2:1 Bimodal age distribution: - Juvenile: 7 years of age (mean) - Adult: 52 years of age (mean) Malignancy Tumor cells increase systemic inflammatory response, leading to increase of autoantigens associated with DM ↑ in DM-associated autoantibodies (Ex. Anti-Mi-2/ Anti-Jo-1) Autoantibodies bind to DNA or RNA in muscles, provoking a systemic inflammatory response ↑ chemokine and cytokine release in endothelial vasculature of muscles Perivascular Capillary necrosis inflammation Lack of blood supply to the myofibers causes endofascicular hypoperfusion and muscle ischemia Muscle tissue damage: Inflammatory infiltrates destroy cellular components of muscle (endoplasmic reticular, myofiber, and keratinocytes) Environmental triggers Infectious agents (ex. Picornavirus) or drugs (ex. statins) provoke immune response Elevated Antinuclear Antibodies Anti-Jo-1 Anti-OJ Anti-Mi2 Anti-SRP Anti-EJ Anti-PL12 Anti-PL7 These processes occur in the skin on the dorsum of the hands, forming hyperkeratotic flat red papules These processes occur in the upper & lower eyelids, causing red-purple discoloration +/- swelling Perifascicular atrophy (Observed on histology) Weaker GI tract musculature Weaker pulmonary musculature Weaker cardiac musculature Dermatomyositis only: Gottron Papules Heliotrope Rash Damaged muscle cells release their internal cellular enzymes into the bloodstream Elevation of muscle enzyme levels in serum: Creatinine kinase (CK), lactate dehydrogenase (LD), aldolase, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) Muscle Biopsy Findings Muscle necrosis, fiber regeneration, diffuse CD8+ T lymphocytes infiltrates Bilateral Muscle Weakness Subacute development, primarily deltoids and hip flexors affected Dysphagia Aspiration, respiratory compromise Atrioventricular defects, tachyarrhythmias, dilated cardiomyopathy Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published April 18, 2019 on www.thecalgaryguide.com

acute-somatic-pain

Acute Somatic Pain: Pathophysiology Acute tissue damage, from three types of causes: Mechanical (eg: sharp pin) Thermal (eg: hot stove) Chemical (eg: inflammation) Nociceptors activated at site of injury (1st order sensory neurons) Nociceptive fibres (A∂ and C) carry noxious sensory information to the ipsilateral dorsal horn of the spinal cord Excitatory neurotransmitters are released and stimulate 2nd order sensory neurons 2nd order sensory neurons immediately cross the midline of the spinal cord, and ascend up the opposite side’s anterolateral (aka spinothalamic) tracts, terminating in various locations: Authors: Lisa Murphy Yan Yu* Reviewers: Mackenzie Gault Melinda Davis* * MD at time of publication Nociceptors: neurons that detect noxious or painful stimuli and carry this information to the spinal cord. There are two major types: A∂ fibres: myelinated, initial “sharp, fast” feeling C fibres: unmyelinated, delayed, “dull, burning” feeling To hypothalamus 2nd order neuron synapses in the hypothalamus Hypothalamic neurons coordinate the body’s visceral response to pain 2 nd To thalamus order neuron terminates in thalamus To brainstem 2nd order neuron synapses in brainstem’s reticular formation To midbrain 2nd order neuron synapses in periaqueductal gray area (PGA) in the midbrain In the thalamus, 2nd order sensory neurons synapse with 3rd order sensory neurons, which carry the signal to the cerebral cortex Stimulates descending pathways to modulate the incoming pain signal Decreased or increased perception of pain Pain localization and sensation Emotional and behavioural response ↑ Heart Rate Nausea Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published April 25, 2019 on www.thecalgaryguide.com

Crohn's Disease

Inflammatory Bowel Disease: Clinical findings in Crohn’s Disease Authors: Yan Yu Amy Maghera Reviewers: Jennifer Au Danny Guo Jason Baserman Jessica Tjong Kerri Novak* * MD at time of publication Behavioural Factors: Smoking, over-sanitation Genetic Susceptibility Environmental Factors Diet, bacteria/viruses, drugs, vitamin D Systemic immune response primarily against the GI tract. (Unclear mechanism, mediated by cytokine release and neutrophil inflammation) Inflammation of the GI tract lining - Inflammation is “transmural”, spanning the entire thickness of the intestinal wall from luminal mucosa to the serosa. - The inflammation occurs anywhere in the GI tract from the oral mucosa to the anal mucosa (from ‘gums to bum’) in skip lesion pattern. Atrophy, scarring of the intestinal villi Inflammatory cytokines destroy the mucosa epithelial cells of the GI tract wall, causing cell apoptosis and ulceration ↑ permeability of the blood vessels supplying the GI tract wall Chronic inflammation impairs healing responses Dysregulated wound healingàexcess extracellular matrix deposition Fibrosis leads to scar tissue and thickening of all layers of the GI tract Strictures Inflammation is systemic, affecting: Joints Arthropathy Erythema Impaired absorption of nutrients Weight loss Prolonged GI bleeding Anemia Transporter proteins responsible for Na+ reabsorption gradually disappear from the epithelium More sodium (and thus water) is retained in the GI tract lumen Microperforations can penetrate through the intestinal wall Anal fistulae (“holes” connecting the anus to the skin, bladder, peritoneum, small bowel, etc.) Continued inflammation and/or infection can lead to: Leakage of fluid out of capillaries into the GI tract Luminal edema and swelling Narrowing of GI lumenàbowel obstruction Skin Mouth Eyes Liver nodosum, pyoderma gangreno- sum >5 canker sores Uveitis Iritis, scleritis Sclerosing cholangitis ↓ fat absorption Fatty acids (negatively charged) bind Ca2+, freeing oxalate from Ca2+ ↑ oxalate absorbed into blood & filtered by kidney Calcium oxalate kidney stones Diarrhea Abdominal cramping and pain (see Bowel Obstruction page for full mechanism Anal abscesses Inflammatory masses Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-Published June 15, 2019 on www.thecalgaryguide.com

Ulcerative Colitis

Inflammatory Bowel Disease: Clinical Findings in Ulcerative Colitis Authors: Yan Yu Amy Maghera Reviewers: Jennifer Au Danny Guo Jason Baserman Crystal Liu Danielle Chang Kerri Novak* * MD at time of initial publication Inflammation is systemic, affecting: Environmental Factors Diet, bacteria/viruses, drugs Genetic Susceptibility Behavioral Factors: In UC, smoking and appendectomy are actually protective (unknown reason) Immune response against the GI tract. (Unclear mechanism, but thought to be mediated by cytokine release and neutrophil infiltration) Inflammation of the GI tract epithelial lining - Starting at the rectum and moves up the colon and is continuous (does not invade the small intestine) - Inflammation affects the mucosal and submucosal only Diarrhea, abdo pain and cramping causing avoidance of food Weight loss Apoptosis of GI tract mucosa Transporter proteins responsible for Na+ reabsorption gradually disappear from the epithelium Ulceration, into the anus, and more severe Prolonged Bleeding - GI and anus Anemia, often iron deficiency Inflammation ↑ permeability of the blood vessels supplying the GI tract wall Fluid leak out of capillaries into GI tract wall, causes edema and swelling Swelling narrows the GI tract lumen, causing bowel obstruction Inflammation, ulceration, or infection at the anus (all involve the RECTUM!) Anal irritation stimulates autonomic and somatic nerves leading up to the brain, causing the pt to want to defecate Tenesmus, urgency, frequency (feeling or urgency to defecate, but little stool is produced) Joints Skin Arthroplasty/ joint pain Erythema nodosum, pyoderma gangrenosum Mouth >5 canker sores More sodium (and thus water) is retained in the GI tract lumen Bloody Diarrhea, usually bloody due to anal bleeding and ulceration bleeding Abdominal Cramping and pain (see Bowel Obstruction page for full mechanism) Eyes (uvea, iris, sclera) Liver Blood Uveitis Iritis, scleritis Sclerosing Cholangitis Autoimmune hemolytic anemia Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-Published May 5, 2019 on www.thecalgaryguide.com

perforated-viscous

Perforated “Viscous” (aka. GI tract; bowels): Author: Yan Yu Reviewers: Michael Blomfield, Tony Gu, Dean Percy, Danny Guo Maitreyi Ramran* * MD at initial time of publication Chest X-Ray (CXR) Pathogenesis and Clinical Findings Diverticulitis Crohn’s disease Peptic ulcer (H. pylori infection, NSAID use, ICU stress, etc) Appendicitis Malignant neoplasm Irritates visceral peritoneum, stimulates autonomic nerves Severe inflammation causes destruction of GI tract mucosa Over time, Perforation of the GI tract wall Bowel contents (air, fluids) released into peritoneal cavity Massive peritoneal inflammation Diagnostic investigations if a GI perforation is suspected Dull diffuse abdominal pain Severe, Sharp abdominal pain with peritoneal signs Abdominal X-ray Irritation of parietal peritoneum, stimulates somatic nerves • Abdominal X-ray • Intra-peritoneal air will coat the GI tract surfaces, giving them a faint white outline under X-ray • Chest X-ray of upright patient (Diagnostic) • Intra-peritoneal air will rise above the peritoneal fluid when pt is upright, accumulating under the right hemi-diaphragm. • Note: air under left hemi-diaphragm = normal gastric bubble • CT? Most patients with suspected GI perforation will get a CT scan, but this is not the diagnostic gold standard (and access to CT can be limited, especially in rural settings) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-Published June 30, 2019 on www.thecalgaryguide.com

acanthosis-nigricans-pathogenesis-and-clinical-findings

Acanthosis Nigricans: Pathogenesis and clinical findings Authors: Laura Chin Reviewers: Taylor Woo Crystal Liu Laurie Parsons* * MD at time of publication Medications E.g. systemic glucocorticoids, injected insulin, oral contraceptives Hyperinsulinemia Insulin inhibits IGFBP 1&2 secretion Genetic Syndromes E.g. Down syndrome, Rabson- Mendenhall syndrome, congenital generalized lipodystrophy Defects in insulin receptor or anti-insulin receptor antibody production Insulin Resistance ↑ IGFR1 binding Type 2 Diabetes Mellitus Polycystic Ovarian Syndrome Obesity Neoplasms E.g. gastric carcinomas Excess IGF-1, TGFα, and FGF production TGFα is structurally similar to EGFα TGFα can bind to EGFR ↑ EGFR binding Inheritable Mutations E.g. FGFR3 activating mutation ↑ free IGF-1 ↑ FGFR binding Moist environment and rubbing of intertriginous skin Skin inflammation and thinning Bacterial or yeast infection Erosions Malodour Dermal keratinocyte and fibroblast growth and differentiation of neck and intertriginous areas, occasionally mucosal surfaces Hyperkeratosis Abbreviations: • IGF-1 – insulin-like growth factor • IGFR1 – insulin-like growth factor receptor-1 • IGFBPs – insulin-like growth factor binding proteins • FGFR – fibroblast growth factor receptor • TGFα – transforming growth factor-alpha • EGFα – epidermal growth factor-alpha • EGFR – epidermal growth factor receptor Hyperpigmentation Crusting Velvety plaques Pain Pruritis Pus Acanthosis Nigricans Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published July 14, 2019 on www.thecalgaryguide.com

intraventricular-hemorrhage-in-preterm-infants-clinical-findings-and-complications

Intraventricular hemorrhage (IVH) in preterm infants: Clinical findings and complications Authors: Alexa Scarcello Reviewers: Nicola Adderley, Emily Ryznar, Yan Yu*, Jennifer Unrau* * MD at time of publication Volpe Grading Grade I: germinal matrix hemorrhage with no or minimal IVH (<10% of ventricular area) Grade II: IVH (10-50% of ventricle) Grade III: IVH (>50% of ventricle; usually distends lateral ventricle) Grade IV/Intra-parenchymal echodensity (IPE): periventricular hemorrhagic infarction Inflammation/dysfunction of arachnoid villi ↓ absorption of CSF 2° to obstruction of arachnoid villi Communicating hydrocephalus (IVH grades II-IV) Venous congestion Venous infarction Periventricular hemorrhagic necrosis Destruction of periventricular motor tracts Cerebral palsy Rapid significant blood loss ↓ intravascular blood volume Hypotension ↓ bloodflow to the brain to support brain function Intraventricular Hemorrhage (IVH) hemorrhage in periventricular subependymal germinal matrix Ultrasound: blood in germinal matrix, ventricles, or cerebral parenchyma Sudden ↓ hematocrit Blood irritates contiguous structures Variable neurologic findings; including altered level of consciousness, hypotonia, apnea, etc Neuro- developmental abnormalities (varying severity) See slide - Hydrocephalus: Clinical Findings in Pediatrics This mechanism leads to three different possible clinical manifestations: 1. Silent Presentation (most common) 2. Stuttering/Saltatory Course: non-specific findings - hypotonia, apnea, altered level of consciousness, bradycardia, and ↓ Spontaneous movements 3. Catastrophic Deterioration (least common) Stupor or coma, decerebrate posturing, seizures, bradycardia, metabolic acidosis, bulging fontanelles, abnormal pupillary reflexes, inappropriate ADH secretion Notes • Incidence & severity are inversely proportional to gestational age • 50% occur within 1st day of life, 90% by 3rd day • As explained in the flow chart, the postnatal clinical presentations of IVH fall into three categories (1-3) • Symptoms of catastrophic bleeds are uncommon and usually caused by rapid significant blood loss with subsequent neurologic findings 2° to meningeal irritation, inflammation, and potential mass effect/acute hydrocephalus; severe bleeds may also occur in the absence of clinical findings attributable to IVH Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published July 27, 2019 on www.thecalgaryguide.com

Appendicitis

Appendicitis: Pathogenesis and Clinical Findings Authors: Yan Yu Wayne Rosen* Reviewers: Wendy Yao Laura Craig Noriyah AlAwadhi* * MD at time of publication Dull, crampy, diffuse peri- umbilical pain Pt may develop fever, diarrhea, constipation, vomiting or anorexia as inflammation worsens Focal, intense, persistent RLQ pain, abdominal guarding and peritoneal signs (i.e. percussion and rebound tenderness Epidemiology Dx of healthy adults: • Men > women • Commonly 10-30 years old, can present at any age • Most common cause of acute abdomen (5% prevalence in all ethnicities) The appendix is anatomically located in the RLQ; appendicitis may be confused with disorders of surrounding structures: Gynecological Diseases • RuleoutpregnancywithHCG pregnancy test • Rupturedovariancyst • Ectopicpregnancy • Mittelschmerz(mid-cycle pain) Gastro-intestinal Diseases • Meckel’sdiverticulum (presents identically to appendicitis; surgically located 2 feet from ileocecal valve; mostly seen in children) • Diverticulitis(presentsasleft sided appendicitis) Non-GI Abdominal Issues • Mesentericadenitisinkids <15: swollen mesenteric lymph nodes • Renalcolic Obstruction of appendiceal lumen (by fecalith, fibrosis, neoplasia, foreign bodies or lymph nodes in kids) Appendix distension and spasms ↑ lumen pressure, ↓ blood flow to appendix Ischemia, tissue necrosis, loss of appendix structural integrity Bacterial invasion of the appendix wall, causing transmural inflammationandnecrosis Stretching of visceral peritoneum, stimulation of autonomic nerves T9-T10 Progression of inflammation over several days (variable length of time) Irritation of parietal peritoneum, stimulation of somaticnerves If appendix not surgically removed Perforation of colon wall, causing peritonitis, abscesses or death Note: Symptoms hugely variable. Only 30% present with classic history. Diagnosis is mostly clinical. Further investigations: CBC: Leukocytosis (due to inflammatory response) CT: Gold standard test. Thickened visceral membrane with enhancing (white) rim due to ↑ blood flow Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-Published July 27, 2019 on www.thecalgaryguide.com

Acute GI Related Abdominal Pain

Acute GI-Related Abdominal Pain: Pathogenesis and Characteristics Authors: Yan Yu Wayne Rosen* Reviewers: Laura Craig Danny Guo Julia Heighton Maitreyi Raman* * MD at time of publication Peritoneal cavity Visceral peritoneum (innervated by autonomic nerves) Bowel stretching, pulling, contracting Abdominal pain type: Diffuse, non-localized Dull, crampy, periodic Not associated with movement Patient may writhe around, trying to get rid of the pain Mesentery Intestinal lumen Parietal peritoneum (innervated by somatic nerves) Cross-section of the GI tract Cuts, structural damage, and inflammation in the bowel Important Notes • Acute abdominal pain can also result from non- gastrointestinal causes, such as kidney stones, female reproductive tract issues, and urinary tract issues. For simplicity’s sake, only the GI-related acute abdominal pain disorders are listed here. • The DDx of visceral abdominal pain is broad. Please consult relevant sections of the Calgary Black Book for the DDx. • Keep in mind that visceral abdominal pain can also be caused by the “acute abdomen” diseases (if the diseases are presenting in their initial phases). • • • • • • Abdominal pain type: Sharp, well-localized Excruciatingly painful, persistent Associated with movement of bowels Patient often lies still to avoid abdominal vibration Peritoneal signs Abdominal guarding, pain with abdominal vibration (coughing, shaking, percussion, palpation) Transition from diffuse to localized pain can indicate disease progression (e.g. from visceral to parietal peritoneal inflammation) Note: bowel obstruction may or may not present as acute abdominal pain Bowel Infarction Appendicitis Diverticulitis Acute Cholecystitis Acute Pancreatitis Perforated Ulcer DDx of an “acute abdomen”: A sudden, non-traumatic disorder of the abdomen that needs urgent diagnosis and treatment. Each topic will be further explored in their respective slides. Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-Published July 27, 2019 on www.thecalgaryguide.com

Erythema Nodosum pathogenesis and clinical findings

Erythema Nodosum: Pathogenesis and clinical findings Authors: Merna Adly Reviewers: Taylor Evart Woo Crystal Liu Yan Yu* Laurie Parsons* * MD at time of publication Epidermal layer Dermal-Epidermal Junction Dermal layer Subcutaneous Fat Layer Phase 1-5. Septal Fibrosis made of inflammatory cells, such as T lymphocytes, histocytes and eosinophils Genetic Dysregulation Infections (Ex. Streptococcal Pharyngitis) ~28-48% of cases Medications (Ex. Birth Control Pills, Sulfa drugs) ~3-10% of cases Malignancy (ex. Lymphoma) Autoimmune conditions (ex. Sarcoidosis and Inflammatory Bowel Disease) ~11-25% of cases Pregnancy ~1-3% of cases Antigenic Stimuli / Bacteria / Viruses / Chemical Agents all could trigger the following process: Phase 1. Neutrophils Infiltrate the fibrous septa between fat lobules in the subcutaneous fat Phase 2. Neutrophils release reactive oxygen species, leading to oxidative tissue damage and inflammation Phase 3. Opening of inter-endothelial junction and the migration of more inflammatory cells into the septal venules, including macrophages, histocytes, and eosinophils Phase 4. Macrophages secrete inflammatory cytokines, which stimulates the proliferation of more helper T cells (Th1) Phase 5. Th1 cells secrete more cytokines, leading to the further release of Th1 cytokines and mediating the immune complexes deposition in the septal venules of the subcutaneous fat (panniculitis). The Th1 immune reaction is called Type IV Delayed Hypersensitivity Reaction Phase 6. Activated macrophages produce hydrolytic enzymes and transform into multi- nucleated giant cells, called Miescher’s Radial Granulomas. These consist of small, well defined aggregations of small histocytes arranged radially around a small cleft of variable shapes in the septal venules of the subcutaneous fat Phase 1-4. Lesions are red tender nodules, poorly defined, vary in size from 2-6 cm, and usually on shins ( 1st week) Fat Lobules T lymphocytes Macrophages Note: we’ve done extensive research and can’t figure out why erythema nodosum happens mostly on the shins. If you have an answer, please email us! Phase 5. Lesions become tense, hard, and painful; and they change in color into bluish or livid. (2nd week) Phase 6. Lesions become fluctuant as in abscess, but do not ulcerate. Lesions fade to a yellowish color Epidermal layer Dermal-Epidermal Junction Dermal layer Subcutaneous Fat Layer Phase 6. Miescher’s Radial Granulomas Fat Lobules T lymphocytes Macrophages Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published August 25, 2019 on www.thecalgaryguide.com

iga-vasculitis-henoch-scholein-purpura-pathogenesis-and-clinical-findings

IgA Vasculitis (Henoch-Schönlein purpura) : Pathogenesis and clinical findings Authors: Mia Koegler Nela Cosic Reviewers: Crystal Liu Yan Yu* Martin Atkinson* * MD at time of publication Infectious Agents 50% have preceding upper respiratory tract infections, i.e., influenza virus or Group A Strep Drugs I.e., antibiotics (penicillin, erythromycin), NSAIDs and biologics (tumor necrosis factor α inhibitors) Immunogenetic and cellular predisposition Various genetic polymorphisms alter cell- mediated immune response, IgA levels elevated in 50% of people ↑ Circulating galactose-deficient IgA1 (GD-IgA1). Deficiency in galactosylation of IgAà↓ IgA serum clearanceàadhesion of IgA complexes, which then deposit into the endothelial lining of blood vesselsàattraction of various inflammatory cells to the area: Formation of Secretion of Interleukin 8 (IL8) - cytokine that induces Neutrophils infiltrate Activation of complement immune complexes neutrophilic chemotaxis and macrophage phagocytosis the tissue site factors (C3, C4) Leukocytoclastic vasculitis (histopathologic term for small vessels inflamed by neutrophilic autoimmune response) Inflamed cutaneous vessels become enlarged in clusters Symmetrical palpable purpura (red/purple, non- blanchable papules) distributed on lower limbs and buttocks areas Cutaneous small vessel vasculitis (100%) Inflamed gastric vessels - hemorrhage and edema within bowel wall Gastrointestinal (85%) Colicky abdominal pain (commonly in the periumbilical region), nausea, vomiting Gastrointestinal GI bleeding (hematemesis, melena), Intussusception Glomerular mesangial proliferation and inflammation ↑ mast cell deposition in joints Joints (60-85%) Arthralgia's (common), arthritis (especially knees and ankles) Arthralgia often transient. No permanent sequelae Sympathetic nervous system activation Glomerulosclerosis, tubulointerstitial and podocyte damage Renal tissue ischemia ↑ Na sensitivity in renal tubules (↑ Na and water retention) Renal (10-50%) Increased renin secretion HTN, nephrotic/nephritic syndrome, renal insufficiency Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published September 1, 2019 on www.thecalgaryguide.com

Acute-diverticulitis

Acute Diverticulitis: Pathogenesis and clinical findings Authors: Yan Yu Wayne Rosen* Reviewers: Laura Craig Noriyah AlAwadhi Danny Guo Erica Reed Maitreyi Raman* * MD at time of publication These regions are perceived in the Left lower quadrant (LLQ) of the abdomen. • PersistentLLQpain,abdominal guarding and peritoneal signs • Constipation/obstipation No bleeding (unlike diverticulosis) Dehydration (low JVP, ↑ resting HR, orthostatic hypotension) Inherent weakness in the muscle layers of the colonic wall Low Fiber diet ↑ Stool transit time (↓colonic motility) Stool build-up, ↑ pressure in colonic lumen Epidemiology • Diagnosis of developed nations, total prevalence = 15% • More prevalent with ↑ age: • 30-50% by age 60 • 70% by age 80 Diverticula most commonly form in the descending and sigmoid colon Triggers cytokine release Irritationofparietal peritoneum → stimulation ofsomaticnerves Inflamed vessels are more permeable & leak fluid from the blood into the colon Mucosal and submucosal layers of the colon wall herniates through the circular muscle layer, creating colonic diverticula Continued stress on diverticula causes micro-perforations → bacterial infection Inflammation of diverticula reaches parietal peritoneum Clotting of blood in the blood vessels feeding diverticula Continued inflammation of diverticula causes complications over time Fever Complete bowel perforation (medical emergency) Fistulae (through bladder, vagina, skin or gut) Colonic fibrosis → GI strictures, colonic obstruction Abscesses Further Investigations: • CBC: leukocytosis (due to inflammatory response) • CT = Gold Standard Diagnostic test: shows inflamed diverticuli as well as complications (i.e. free air in peritoneum due to microperforations) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-Published September 1, 2019 on thecalgaryguide.com

virchows-triad-and-deep-vein-thrombosis-dvt

Suspected Deep Vein Thrombosis (DVT): Authors: Dean Percy Yan Yu Reviewers: Tristan Jones Ryan Brenneis Man-Chiu Poon* Maitreyi Raman* * MD at time of publication Pregnancy, Oral Contraceptives (OCP) Pathogenesis and Complications Platelet Activation Increased clot formation Hypercoagulable State ↑ ability for the blood to coagulate upon stimulation Inherited Disorders Congenital defect in coagulation (ie. Factor V Leiden, Factor II mutation, Protein S/C deficiency) ↑ blood clotting ability Estrogen promotes hypercoagulability, especially in presence of other risk factors Notes: • Venous thrombus causes pulmonary embolism, arterial thrombus causes stroke • Previous DVT is risk factor for current DVT Trauma/Surgery Malignancy Abnormal release of coagulation-promoting cytokines Systemic injuryà activation of coagulation cascade Hypertension Bacteria Artificial Valve Physically damages blood vessel walls Adhere/invade vessel wall Abnormal surface Vessel Injury Exposes tissue factor on damaged cells and subendothelium for vWF binding Virchow’s Triad Venous Stasis Low blood flow rate over site of vessel injury, concentrating blood clotting factors at that site Fat contains more aromatase, converts more androgens to estrogen Sedentary lifestyle, poor venous return Obesity Clot formation typically occurs in leg veins Deep, large veins allow for blood pooling (stasis, hypercoagulability) Venous return from legs often against gravity (stasis) Valves in leg veins prone to backflow (stasis) ↓ muscle motion = ↓ venous blood flow Fracture, immobilization, bedrest, long vehicle/airplane ride Destruction of vein valve by clot Venous Insufficiency Clot prevents blood from returning to heart. Blood accumulating in the leg results in unilateral leg edema and venous inflammation (redness, warmth, tenderness) 1. 2. 3. Clot embolizes to the lungs Thromboembolus -*Pulmonary embolism (acute life threatening complication) -Chronic thromboembolic pulmonary hypertension Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-Published September 1, 2019 on thecalgaryguide.com

Acute-Pancreatitis

Acute Pancreatitis: Pathogenesis and Clinical Findings Authors: Yan Yu Reviewers: Laura Craig Noriyah AlAwadhi Ryan Brenneis Maitreyi Raman* * MD at time of publication Associated signs due to intra- abdominal hemorrhage from an unknown mechanism (classically associated with pancreatitis, but happens in <1% of cases): Note: It is not enough to just diagnose “acute pancreatitis”. Full management requires determining underlying etiology with further work-up. Alcohol ↑ Toxic metabolites within pancreas and Spincter of Oddi Spasms Gallstones Migration to common bile duct blocks Sphincter of Oddi Hypertriglyceridemia Unknown mechanism (rare) Idiopathic Further investigations: CBC: Cell counts elevated, due to sever hypovolemia Serum [Lipase]: Gold Standard Diagnostic Test; rupture of pancreatic cells releases lipase into circulation Pancreatic secretions back up, ↑ pressure within pancreas Hypercalcemia (Rare; Ca2+ depositions in bile ducts block outflow of pancreatic secretions) Since pancreas is retroperitoneal, somatic nerves in the parietal peritoneum are directly stimulated Inflammation triggers cytokine release Inflamed pancreas irritates adjacent intestines, causing ileus Inflamed, more permeable blood vessels leak fluid into pancreas • • Cullen’s sign (bruising in peri-umbilical region) Grey-Turner’s sign (bruises along both flanks) Sudden, severe epigastric pain (with peritoneal signs), radiates to the center of the back Fever, nausea/vomiting (general signs of inflammation) Diminished bowel sounds Profound dehydration (flat JVP, hypotension, tachycardia, oliguria) – may happen, not always 1. Pressure compresses pancreatic blood vessels, causing tissue ischemia. 2. Activation of inactive proteases (zymogens) digesting pancreatic tissue Necrosis (death) of pancreatic cells Inflammation self- perpetuates Massive systemic inflammatory response 2 main complications, usually detected on CT; may happen, but not always 1. Pancreatic pseudocyst (enlargement of the pancreas due to fluid accumulation) 2. Pancreatic necrosis/abscesses (death of a part of the pancreas) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-published September 1, 2019 on thecalgaryguide.com

Infantile Colic

Infantile Colic: Pathogenesis & Clinical Findings Gastrointestinal (GI) factors ↑ bile acid wasting ↓ bile acid production in immature in immature gut enterohepatic circulation ↓ bile acid availability Psychosocial factors Infant temperament Over/understimulation Parental variables (e.g. parental stress) Collectively, these factors influence the infant’s reactivity to adverse stimuli and the caregiver’s perception of whether crying is problematic. Other biologic factors Poor feeding techniques: under/ overfeeding, swallowing air, infrequent burping Altered gut motility GI discomfort Infantile Colic Dietary intolerances: cow’s milk protein, lactose ↑ gas production and gut distension ↓ mucosal barrier function Loss of bacteriostatic effects of bile acids Immature enteric nervous system Intestinal microbial imbalance ↑ intestinal permeability ↑ systemic inflammation Altered central and enteric neuronal function via microbiota-gut-brain axis Altered perception of pain and other GI stimuli Crying for no apparent reason that lasts > 3 hours/day and occurs ≥ 3 times/week for > 3 weeks in an otherwise healthy infant < 3 months old. There must be normal growth, development, and physical exam. Colic itself is a benign, self-limiting condition that resolves with time. Facial flushing or grimacing Tense or distended abdomen Drawing up of legs Clenching of fingers Stiffening of arms Arching of back Distress expressed via behaviour Loud, high- pitched, urgent cry ↑ risk of non- accidental trauma GI factors directly affect infant’s behaviour Hypothesized role of immature CNS regulation of circadian rhythm ↑ parental stress Immature regulation of behaviour Episodes cluster in evening and/or late afternoon ↑ risk of post- partum depression Paroxysmal crying Inconsolable Authors: Simonne Horwitz Nicola Adderley Reviewers: Crystal Liu Yan Yu* Danielle Nelson* * MD at time of publication Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published September 28, 2019 on www.thecalgaryguide.com

Ischemic Colitis

Ischemic Colitis: Pathogenesis and clinical findings Superior and inferior mesenteric arteries (SMA and IMA) supply blood to colon Surgical repair of aorta Borders of SMA and IMA collaterals at the splenic flexure and rectosigmoid junction are vulnerable to ischemia (“watershed” areas) Atherosclerosis and narrowing of mesenteric arteries Low flow state (e.g., CHF, hypotension, arrhythmia) Underlying CAD/PVD Atrial fibrillation, endocarditis Embolic arterial occlusion of SMA and/or IMA Trauma, infection, clotting abnormalities Mesenteric vein thrombosis Vascular risk factors (e.g., smoking, hypertension) Thrombotic arterial occlusion of SMA and/or IMA Endograft coverage of IMA Nonocclusive hypoperfusion Inadequate blood flow to meet the cellular metabolic needs in the colon Ischemic Colitis Tachypnea Tachycardia Hyperthermia Hypotension Ischemic period Loss of oxygen and nutrients to bowel Reperfusion period Influx of O2àreacts to produce more oxygen free radicals Lipid peroxidation Systemic inflammatory response syndrome* Nausea and vomiting Abdominal pain (generally left sided) Peritonitis Leukocytosis Systemic shock (inadequate perfusion to tissue) Author: Audrey Caron Michael Blomfield Reviewers: Tony Gu Yan Yu* Edwin Cheng* * MD at time of publication Systemic shock (inadequate perfusion to body tissue) Hematochezia (Bloody stool) Gangrene (tissue death) Hemorrhage Tissue damage/cell death (starting from mucosa and submucosa going outwards to serosa) Mucosal ulceration Colonic inflammation Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 10, 2019 on www.thecalgaryguide.com

Endometritis

Endometritis: Pathogenesis and clinical findings Prolonged rupture of membranes > 24 hours between amnion rupture and delivery ↑Time for vaginal flora to ascend into the uterus Assisted vaginal delivery Use of forceps or vacuum Multiple digital vaginal exams Manual examination of the vagina to assess cervical dilation Internal monitoring Intrauterine device to monitor the fetus or contractions Group B Streptococcus colonization Opportunistic bacteria present in the normal vaginal flora of up to 30% of women Bacterial Vaginosis Overgrowth of anaerobic bacteria with associated decrease in protective Lactobacillus species Foreign bacterial ascension into the uterus Sepsis Cesarean delivery ↑ Exposure of vaginal flora to the uterus Introduction of bacteria directly into the uterus Spread of infection to myometrial and parametrial layers of uterus Authors: Gabrielle Wagner Reviewers: Danielle Chang Crystal Liu Aysah Amath* * MD at time of publication ↑ Susceptibility to bacterial invasion of the uterine lining Endometritis Postpartum infection of the uterine endometrial lining Activation of innate Fever, immune response Inflammation of uterus Leukocytosis Accumulation of WBCs within vaginal discharge Purulent or foul-smelling lochia (vaginal discharge) Uterine tenderness Pelvic and/or abdominal pain Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 26, 2019 on www.thecalgaryguide.com

Viral-Hepatitis

Viral Hepatitis: Pathogenesis and clinical findings Infection with a virus that targets the Authors: Sean Spence Tyler Anker Yan Yu Reviewers: Dean Percy Crystal Liu Sam Lee* * MD at time of publication liver, e.g. HAV, HBV, HCV, HDV, HEV Hepatocytes are invaded & damaged Foreign particles and tissue damage activate immune systemàliver inflammation Lysis (bursting) of hepatocytes Infection with chronic viruses (HBV and HCV) persist over time and additional symptoms may develop RUQ pain/tenderness If infection is prolonged or severe, inflammation becomes systemic Release of hepatocyte’s cellular contents into the bloodstream Infection with acute viruses (HAV and HEV) resolve over time, and the symptoms above normalize Notes: • HDV can only infect people with concomitant HBV infection • HAV and HBV vaccines are the only ones that currently exist • Not all patients with viral hepatitis will develop each of these symptoms. The presentations vary. Fever, nausea, vomiting ↑ serum ALT, AST ↓ Hepatic metabolic activity (e.g. reduction of gluconeogenesis) ↓Serum Glucose ↓ Synthesis of plasma proteins (albumin, clotting factors, etc) ↓ Albumin, ↑ INR Abbreviations: • HAV - Hepatitis A Virus • HBV - Hepatitis B Virus • HCV - Hepatitis C Virus • HEV - Hepatitis E Virus • RUQ - Right Upper Quadrant • ALT - Alanine Aminotransferase • AST - Aspartate Aminotransferase • INR - International Normalized Ratio ↓ Bilirubin clearance from blood, bilirubin ends up under the skin Jaundice Portal Hypertension Encephalopathy, Splenomegaly, Esophageal Varices, Ascites, Caput Medusae, Edema Encephalopathy, Muscle Wasting, Metabolic Bone Disease, Terry’s Nails, Ascites, Bruising, Clubbing, Edema Spider Nevi, Altered Hair Patterns, Testicular Atrophy, Gynecomastia, Palmar Erythema Progressive deterioration in liver function, possibly ending up in cirrhosis. (See slide on “Cirrhosis: pathogenesis and complications” for more details on mechanisms and full explanations.) Hepatic Insufficiency Hyperestrogenism Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-Published January 12, 2020 on www.thecalgaryguide.com

Innate-Immune-Response

Innate immune response: Pathogenesis and clinical findings Authors: Erin Stephenson Reviewers: Jessica Tjong Crystal Liu Nicola Wright* * MD at time of publication Pathogens overcome chemical barriers (e.g., lysozyme, low pH) Pathogens overcome physical barriers (e.g., epithelium, cilia) Trauma Damage-associated molecular patterns Pathogen-associated molecular patterns Examples of tissue-resident macrophages: • Alveolar macrophages – Lung • Histiocytes – Connective tissue • Kupffer cells – Liver Recognition by pattern recognition receptors (e.g., toll-like receptors) • Mesangial cells – Kidney • Microglial cells – Brain • Osteoclasts – Bone Microbe engulfed and exposed to oxidative burst Microbes destroyed Pus Pro-inflammatory chemokines Recruitment of circulating granulocytes and monocytes Pro-inflammatory cytokines (e.g., IL-1β, TNFα, IL-6) Tissue-resident macrophage activation Antimicrobial proteins Unresolved infection/ inflammation Antigen presented to T cells Recruitment of adaptive immune response Enhanced immune responses Acute phase protein production by liver (i.e., C- reactive protein) Prostaglandin production in the hypothalamus Fever Endothelial tight junctions on vasculature disrupted Intravascular fluid leak into extravascular space Edema Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 19, 2020 on www.thecalgaryguide.com

vomiting-pathogenesis

Vomiting: Pathogenesis Authors: Julena Foglia Reviewers: Varun Suresh Matthew Harding Haotian Wang *Yan Yu *Eldon Shaffer *MD at time of publication Intracranial: Trauma, Infection, Tumor, Stroke ↑ Intracranial pressure Mechanism Unknown Irritation of GI mucosa: Inflammation, Distention, Chemotherapy, Radiation Activates receptors in gut mucosa GI Disease: Upper: GERD, PUD, Cancer Lower: Ischemia, obstruction, IBD Mechanical pharyngeal stimulation Signal travels via vagal and sympathetic afferent nerves Metabolic: Pregnancy, Diabetes, Uremia, Thyroid disease, Hypercalcemia Pain, Smells, Foul Sights, Memories Sensory inputs to cortical region Cerebral Cortex Vomiting (Emetic) Center Toxins circulating in bloodstream: Chemotherapy, Opioids Offending substance travels through circulation and binds to receptors in the CTZ, outside the blood brain barrier Abbreviations: GERD: Gastroesophageal Reflux Disease PUD: Peptic Ulcer Disease IBD: Inflammatory Bowel Disease CTZ: Chemoreceptor Trigger Zone CNX: Cranial Nerve Ten H1: Histamine Receptor M1: Muscarinic Receptor Disrupted inner ear balance: Motion Sickness Activation of H1 & M1 receptors in vestibular center traveling via Cerebellum Stimulates Solitary Tract Nucleus (Medulla) (Medulla) Vagus Nerve (CNX) and enteric nervous system activation, resulting in: Gastric relaxation, ↓ pylorus tone, retrograde duodenal peristalsis Downward diaphragm contraction, abdominal & chest wall muscles contract: ↑ intra-gastric pressure Vomiting (Forceful expulsion of material from stomach and intestines) Upper and lower esophageal sphincter relaxation and glottis closure Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-published February 16, 2020 on www.thecalgaryguide.com

C5-C9-deficiency

C5-C9 deficiency: pathophysiology and clinical findings Authors: Heather Yong Reviewers: Jessica Tjong, Crystal Liu, Yan Yu*, Nicola Wright* * MD at time of publication Normal complement response The complement pathway is a non- specific response to bacterial pathogens Bacterial infection Classical, alternative, or lectin pathway activation Complement cascade MAC formation on bacterial surface C5b, C6, C7, C8, C9 Complement proteins create trans- membrane channels within bacterial cell walls/cell membranes Critical bacterial proteins leak out of the cell, breakdown of entire cell Primary (hereditary) causes Secondary (acquired) causes All are autosomal recessive Biologic therapy ex. eculizumab Absence or suboptimal functioning of Abbreviations: • MAC: Membrane Attack Complex • CH50: Classic Hemolytic Complement Test • AH50: Alternative Hemolytic Complement Test • CNS: Central Nervous System • CSF: Cerebrospinal Fluid ≥1 terminal complement proteins C5-C9 deficiency Inability to form MAC ↑ susceptibility to systemic Neisseria infection Commonly N. meningitidis Rarely N. monorrhoeae Nasopharyngeal colonization of N. meningitidis, ↑ susceptibility to bacteremia CH50 ± AH50 assay No lysis Note: Total complement activity assay <10% activity C5, C6, C7, C9 <50% activity C8 Varied bactericidal action via other complement proteins • Risk of invasive meningococcal disease is 1000-10000X higher in C5-C9 deficiency than in the general population • Reason is unknown • C5-C9 deficient patients are not at greater risk for contracting other gram (-) infections • Clinical meningitis in C5-C9 deficiency is less severe and fatality is rare Bacterial lysis Especially gram (-)ve bacteria like Neisseria Bacteria cross the blood-brain barrier, causing swelling and damaging brain tissue Fatigue, fever, headache, altered mental status, etc. Inflammation of CSF and meninges Activation of dura and pia mater fibres Headache, neck stiffness Bacteria release toxins Damage to surface blood vessels Maculopapular rash Exact mechanism unknown Recurrent meningitis CNS damage due Sepsis to recurrent meningitis Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published February 16, 2019 on www.thecalgaryguide.com

Fecal-Incontinence

Fecal Incontinence: Pathogenesis and complications Note: The majority of fecal incontinence is multifactorial in cause Authors: Timothy Fu Reviewers: Chronic bowel straining Difficult vaginal delivery Direct internal anal sphincter impairment (controls ~70% of anal resting tone) ↓ anal resting tone Aging: Degene- ration of muscle fibers Movement disorders (e.g. arthritis, Parkinson’s); aging is a risk factorà ↓ mobility ↓ timely access to bathrooms Inflammation of colon (e.g., Ulcerative colitis, Radiation proctitis) ↓ capacity of rectal smooth muscle to stretch ↓ capacity to store stool ↑ urgency of defecation ↑ reflex relaxation of internal anal sphincter Chronic diarrhea, diarrhea- predominant irritable bowel syndrome, laxatives Yan Yu* Erika Dempsey* * MD at time of publication Stretch injury of Pelvic surgery Chronic constipation Build up of solid, immobile mass of stool in the rectum Loose stool is able to flow around impacted stool, exiting anal canal (overflow diarrhea) Sensory neuro- pathy (e.g. Diabetes) Altered mental conditions (e.g. stroke, dementia) pudendal nerve (innervating the pelvic muscles and external anal sphincter) Local neuronal damage Impaired pelvic muscle and external anal sphincter motor control Pelvic trauma Rectal prolapse Direct external anal sphincter impairment ↑ Stool volume ↑ Loose stools Rectal hyposensitivity (↓ perception of rectal distension) Patient fails to sense rectal fullness and voluntarily releases their external anal sphincter Voluntary external anal sphincter contraction is no longer sufficient in closing the anus Loose stool is more prone to escape through anal canal compared to solid stool Continence mechanisms are impaired Fecal Incontinence: The unintentional loss of solid or liquid stool Skin Skin Continence mechanisms are intact, but overwhelmed or ignored infection Skin erythema erosion Inability to control what is widely considered a basic, fundamental bodily process ↑ caretaker burden Social stigma ↑ skin contact with acidic irritant (stool) ↑ rate of institutionalization, (e.g., admission into long-term care) ↓ confidence, sense of agency ↑ stress, anxiety Skin inflammation ↓ social activity, work ↓ help-seeking ↓ treatment Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published May 2, 2020 on www.thecalgaryguide.com

Diabetic-Nephropathy

Diabetic Nephropathy: Pathogenesis Type I or Type II Diabetes ↑ Glucose uptake & glycolysis in glomerular & tubular cells Poor glycemic control = ↑ Glucose load ↑ Proximal tubule reabsorption of Na via Na/glucose co-transporter ↓ NaCl to distal tubule Activation of tubulo- glomerular feedback at macula densa to kidney ↑ Activation of renin- angiotensin system (RAS) ↑ Intrarenal angiotensin II ↑ Advanced glycation end products (AGE) Shunting of glucose through non- glycolytic pathways (e.g. polyol) Activation of Protein Kinase C (PKC) pathway Excessive production and accumulation of glycolytic intermediates (e.g. sorbitol, hexosamine, succinate) hyperglycemia Succinate via GPR91 ↑ Free radical production (oxidative stress) Activation of cellular signalling, transcription factors and cytokines (e.g. TGF-β-Smad-MAPK, IGF-1, NF-κB) ↑NADPH oxidase activity ↑Blood volume ↑ Blood pressure ↑ Renal perfusion Relative afferent arteriole dilatation, efferent arteriole constriction Initial ↑ in glomerular filtration rate (GFR) Podocyte loss/injury Authors: Steven Chen Shannon Gui Yan Yu* Reviewers: Julia Heighton Ryan Brenneis Sophia Chou* * MD at time of publication Initial glomerular hyperfiltration at time of diagnosis ↓ Production of matrix metallo- proteinases Aberrant extracellular matrix (ECM) protein expression and accumulation Sheer stress to glomeruli à pressure-induced damage ↑ Glomerular basement membrane permeability to proteins like albumin ↓ Extracellular matrix regulation “Metabolic Pathway” Mesangial matrix expansion Kimmelstiel- Wilson lesions (pink hyaline nodules due to accumulation of damaged proteins) Tubular fibrosis Scarred glomeruli are less able to effectively filter blood ↓ in glomerular filtration rate (GFR) Albuminuria Usually occurs after ~5 years from time of diagnosis in T1DM; can occur at time of diagnosis in T2DM Abbreviations IGF: Insulin-like growth factor MAPK: Mitogen-activated protein kinases NADPH: Nicotinamide adenine dinucleotide phosphate NF-κB: Nuclear factor kappa-light-chain- enhancer of activated B cells TGF-β: Transforming growth factor-β Protein endocytosis into tubular cells causing inflammation “Hemodynamic Pathway” Diabetic Nephropathy Overt diabetic nephropathy may take upwards of 15-25 years to develop Note: The mechanisms presented here have been simplified. The cross- talk and signaling between the metabolic and hemodynamic factors do not manifest in a step-wise fashion, but rather occur in parallel. Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published May 3, 2020 on www.thecalgaryguide.com

Infarctus du myocarde: Antécédents médicaux

Infarctus du myocarde: Antécédents médicaux Infarctus du myocarde (nécrose 8ssulaire) Auteur: Yan Yu Traductrice: Olivia Genereux Réviseurs: Sean Spence Tristan Jones Nanette Alvarez* Marie Giroux* *MD au moment de publication Sang du ventricule gauche reflue à l’oreille[e gauche et finalement s'accumule dans le système vasculaire pulmonaire Haute pression du système vasculaire pulmonaire force fluide hors des capillaires et dans l'interstitium pulmonaire et les alvéoles Inflammation myocardique locale Médiateurs inflammatoires irritent les nerfs cardiaques (plexus cardiaque) ̄ Fonc8on systolique (myocarde nécro6que ne peut pas se contracter suffisamment) Invasion généralisée des cytokines inflammatoires Cytokines agissent les régulateurs de température hypothalamique Fièvre légère Irritation des nerfs sympathiques afférents (T1-T4) Signal entre moelle épinière, a/n dermatomes T1-T4 Cerveau perçoit irritation des nerfs comme douleur des dermatomes T1-T4 Douleur écrasante, pression, oppression de la poitrine: Souvent rétrosternale, avec radiation à épaule, cou et l'intérieur des deux bras (D>G) (Apparition: au repos, crescendo) IrritaNon des branches cardiaques du nerf vague AcNvaNon réponse vasovagale Fatigue, étourdissements, nausée, vomissement ↓ volume systolique (VS) ↓ debit cardiaque (DC) ­ Activité sympathique (pour essayer de maintenir DC) ­ Sueurs (diaphorèse) Peau moite VasoconstricNon généralisé Vasoconstriction des artérioles de peaux Peau froide Interstitium pulmonaire mou ↓ compliance pulmonaire d Fluide compresse les voies respiratoires, ↑ résistance au flux d’air Abrévia8ons: • a/n – au niveau À Noter: Douleur myocardique ischémique peut présenter différemment entre les patients, mais les symptômes récurrents habituellement présentent les mêmes pour un patient donné. Muscles respiratoires travaillent plus fort pour venNler les poumons Essoufflement (difficulté à respirer) Légende: Physiopathologie Mécanisme Signe/Symptôme/Résultats de Laboratoire Complications Publié Janvier 20, 2013 sur www.thecalgaryguide.com

preterm-labour-pathogenesis-maternal-complications

Preterm Labour: Pathogenesis & Maternal Complications Cervical Procedures Removing part of the cervix Ex. Cone biopsy, cervical LEEP Genitourinary Infections E.g. Urinary tract infection, bacterial vaginosis, chorioamnionitis, abnormal vaginal flora ↑ bacterial colonization of fetal membrane ↑ bacterial enzymes and immune reactions Antepartum Hemorrhage ↑ risk placental abruption ↑ decidual tissue factor release Activates coagulation cascade ↑ thrombin ↑ proteases Substance Use Smoking or cocaine use Vasoconstriction in uterine circulation, endothelial dysfunction Placental hypoperfusion and ischemia ↑ fetal ACTH ↑ placental prostaglandins Maternal Stress Malnutrition, depression, trauma- related disorders, work-related stress ↑ cortisol ↑ placental corticotropin releasing hormone Uterine Abnormalities Mullerian duct anomalies: congenital abnormalities in uterine shape Septate uterus: ridge of tissue dividing uterus into two horns Intracavitary leiomyoma: benign mass inside uterus ↑ Uterine volume Maternal Genome Family hx or personal hx of preterm birth, previous preterm premature rupture of membrane ↓cervical stroma & ↑cervical scarring ↓ cervical glandsà ↓ mucous production ↑risk of infection ↑ inflammation ↑prostaglandins Cervical collagen degradation Rapid growth exceeds blood supply Ischemia & necrosis of fetal tissue ↑prostaglandins and cytokines ↓ functional volume of uterine cavity Multifetal pregnancy, poly- hydramnios ↓tensile strength and plasticity Uterine stretch Upregulation of oxytocin receptors Genes for ↑ risk Mechanism unknown Cervical Insufficiency Pathologic cervical dilation and/or effacement (thinning) Authors: Skye Russell Reviewers: Danielle Chang, Crystal Liu, Yan Yu*, Nicholas Papalia* *MD at time of publication Digest and weaken amniotic membrane Preterm Premature Rupture of Membranes ↑ myometrial sensitivity to oxytocin Uterine contractions Preterm Labour Uterine contractions and cervical change occurring <37wk gestational age ↑ Risk of future preterm labour and preterm birth Abbreviations: • LEEP – Loop electrosurgical excision procedure • ACTH – adrenocorticotropic hormone Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published July 12, 2020 on www.thecalgaryguide.com

acute-pancreatitis-complications

Acute pancreatitis: Complications Inflammation causes vasodilation and vasculature leakage Mild, (85%): Interstitial edematous pancreatitis Local accumulation of fluid in the pancreas <2 weeks after onset Acute peripancreatic fluid collection (not encapsulated) Walled off by fibrous & granulation tissue >2 weeks after onset Pancreatic pseudocyst (completely encapsulated) Peritoneal irritation à pain Large cyst can (very rarely) compress surrounding bowel Acute Pancreatitis Inflammatory cytokines are released from damaged pancreas If recurrentàchronic pancreatitis (see relevant slide) Inflammation damages pancreatic exocrine cellsàInappropriate release of pancreatic enzymes into surrounding tissue & vasculature àdigesting pancreatic parenchyma Authors: Nissi Wei, *Yan Yu Reviewers: Dean Percy, Miles Mannas, Varun Suresh, Brandon Hisey, *Kerri Novak, *Sylvain Coderre * MD at time of publication complete resolution (most cases) Necrotic tissue is vulnerable to infection (esp. Gram neg GI bacteria) inflammation & necrosis activate cytokine cascade Severe, necrosis (15%): Necrotizing pancreatitis Local infection Severe pancreatic inflammation shifts body fluid into retroperitoneal spaceàintravascular volume depletion Systemic Inflammatory Response Syndrome (SIRS) (see relevant slide) Organ failure (may be sole feature on presentation) Stagnant fluid can more easily become infected Infection spreads to bloodstream Cardiac failure Hypovolemic shock Renal failure Local accumulation of fluid & necrosis in the pancreas < 4 weeks after onset: Acute necrotic collection (not encapsulated) Walled off by fibrous & granulation tissue > 4 weeks after onset walled-off necrosis (completely encapsulated) When treated with excess fluid resuscitation: Intra- abdominal hypertension Respiratory failure (ARDS) Disseminated intravascular coagulation (DIC) Bowel obstruction Gastric outlet (see relevant slide) obstruction Infected pancreatic necrosis Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published September 20, 2016, updated September 7, 2020 on www.thecalgaryguide.com

Cellulitis

Cellulitis: Pathogenesis, clinical findings and complications Authors: Tegan Evans, Spencer Yakaback Reviewers: Brian Rankin, Timothy Fu, Laurie Parsons*, Yan Yu* * MD at time of publication Cracked skin Surgery Normal Skin Epidermal layer Dermal-Epidermal Junction Dermal layer Subcutaneous fat Resident skin flora: Coagulase-negative Staphylococci* Transient skin flora: Staphylococcus aureus* Streptococcus pyogenes Gram negative bacteria Fungi Pathogen in deep dermis and subcutaneous fat *most common pathogens Break in skin barrier (may not be obvious) and entry of pathogen Risk Factors: Immunocompromised Host: -Diabetes mellitus+ -Lymphedema -Malnourishment -Older patient+ -Obesity+ -Peripheral vascular disease General Infection Risk: -History of cellulitis+ +highest risk factors Risk Factors for MRSA Cellulitis: Increased exposure to MRSA: -Contact sports -Crowded living conditions -Health care workers -Indigenous descent -Sharing towels, equipment Increased susceptibility: -Immunodeficiency -Young age Direct inoculation (e.g. trauma) Organism virulence overwhelms host defense mechanisms (related to risk factors) Cellulitis: A bacterial infection in which pathogens penetrate deep dermis and/or subcutaneous fat Cytokines activate immune response Accumulation of pus (bacteria, white blood cells, dead skin) Abscess formation Infection spreads to nearby lymph nodes Lymphadenitis Infection spreads through lymph vessels Ascending lymphangitis Local inflammatory response in skin Pain Warmth Edema Erythema (redness) with indistinct margins Vesicles and bullae Organisms penetrate blood vessels Bacteremia (presence of bacteria in blood) Systemic inflammation Distant spread to bone Osteomyelitis Distant spread to endocardium (inner lining of heart chambers and valves) Endocarditis Fever Malaise Chills Sepsis (rarely) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published September 27, 2020 on www.thecalgaryguide.com

Tumour-Lysis-Syndrome

Tumour Lysis Syndrome High sensitivity to treatment Highly proliferative malignancy with ↑cell-turnover Large tumour mass Author: Joshua Yu Reviewers: Hannah Yaphe Davis Maclean Tejeswin Sharma Yan Yu* *Peter Duggan *ManChiu Poon *Lynn Savoie *Juliya Hemmett * MD at time of publication High serum phosphate High serum Advanced uric acid Age Volume depletion Pre-existing renal disease Patient risk factors Initiation of cancer treatment Massive tumour cell lysis and release of cellular contents into circulation overwhelms homeostatic mechanisms Tumour properties (hematologic malignancies most common) Though rare, aggressive tumours can spontaneously lyse without treatment Intracellular potassium released into bloodstream Intracellular phosphate released Hyperphosphatemia ↑ serum phosphate Intracellular lactate dehydrogenase (LDH) released ↑ serum LDH Intracellular nucleic acids released Nucleic acids metabolized to uric acid Hyperuricemia ↑ serum uric acid Hyperkalemia ↑ serum potassium (see Hyperkalemia: clinical findings) Uric acid (a crystallizing substance) ↑ precipitation of calcium phosphate ↑ filtration of poorly soluble uric acid into acidic environment of renal tubules Serum phosphate binds serum calcium, forming solid calcium phosphate precipitate crystals High levels of calcium phosphate ↑ uric acid precipitation Uric acid precipitates as crystals and deposits in kidney tubules and collecting ducts Tubular injury and/or intraluminal obstruction Endothelial dysfunction in renal vasculature Renal inflammation, vasoconstriction, and impaired renal vascular autoregulation Decreased renal filtration Acute Kidney Injury (see Acute Kidney Injury Overview) Crystal deposition in the heart Depletion of soluble calcium Hypocalcemia Calcium phosphate crystals deposit in kidneys Main mechanism of Acute Kidney Injury Cardiac Arrythmias ↓ serum calcium (see Hypocalcemia: clinical findings) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published October 25, 2020 on www.thecalgaryguide.com

Multiple-Sclerosis-on-Brain-MRI

Classic Findings of Multiple Sclerosis (MS) on Brain MRI Authors: Evan Allarie Davis Maclean Viesha Ciura* Reviewers: Yan Yu* * MD at time of publication infiltrates in the infratentorial region Note: variation in findings exist. The findings shown here are not exhaustive but are some of the most common areas implicated on brain MRI in MS. Most common sites that lesions are observed are: juxtacortical regions, periventricular, infratentorial, spinal cord, and the optic nerve. However lesions can occur anywhere there is myelin in the CNS. Active inflammation and destruction allows for gadolinium contrast to cross the blood- brain barrier, which can be visualized as a marker of active inflammation in MS Classic optic nerve (CN II) lesion seen in optic neuritis. Gadolinium enhancement (↑ signal intensity of lesion after gadolinium injection) in this T1 image demonstrates active inflammation Image Credits: Dr. Viesha Ciura For further pathogenesis, see the Calgary Guide slide: Multiple Sclerosis (MS): Pathogenesis and Clinical Findings Inflammation within the central nervous system (CNS) T-cell, B-cell, and macrophages infiltrate CNS Infiltration occurs through veinsàlocal inflammation Perivenular infiltrates around the medullary veins (perpendicular to ventricles) Inflammation and blood-brain barrier destruction ↑ extravascular inflammatory fluid around lesions, which appears hyperintense/bright Loss of neuronal/axonal density in affected region, replaced by gliosis over time Lesions extend out around veins, creating characteristic ovoid lesions Classic hyperintense T2/FLAIR perpendicular periventricular plaques following the medullary veins – ‘Dawson’s Fingers’ Middle cerebellar peduncle T2/FLAIR hyperintense lesion in classic location for MS Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published October 25, 2020 on www.thecalgaryguide.com

Bronchiolitis-updated

Bronchiolitis: Pathogenesis and clinical findings Viral pathogen, most commonly respiratory syncytial virus (RSV) - but can be others such as rhinovirus, adenovirus, parainfluenza, influenza, and coronaviruses - initially colonizes the nasopharyngeal mucosa Virus travels via the epithelium to the lower airways to the terminal bronchioles (small airways) Authors: Nick Baldwin Rebecca Lindsay Reviewers: Kayla Nelson, Yan Yu Timothy Fu, Danielle Nelson* *MD at time of publication Upper airway mucosal inflammation Bronchiolitis (bronchiole inflammation) Apnea (cessation of breathing; via unknown mechanism, potentially apnea reflex) RSV-fusion protein facilitates fusion of the virus to the host cell and directs viral penetration as well as facilitates fusion of the infected cell with its healthy neighbors Forms syncytia (multinucleated cells) Cytokines are released into circulation ↑ thermo- regulatory set- point at the hypothalamus Mild Fever Copious coryza (nasal discharge) Protein and fluid leak into nasopharyngeal interstitium ↑ Capillary permeability Protein and fluid leak into the bronchiole interstitium, accumulating around airway walls Airway wall becomes thickened, more readily apparent on x-ray Peribronchial cuffing (X-ray finding: bronchi appear like thickened ‘cuffs’ when viewed head-on) Inflammation stimulates the upregulation of mucous secreting goblet cells ↑ mucous production Mucous within alveoli ↑ intra- alveolar surface tensionà collapsing alveolar walls During inspiration, air enters the collapsed alveoli if airway is not yet occluded ↑ intra-alveolar pressure causes the alveoli to suddenly pop open Inspiratory crackles on auscultation Syncytia slough off the bronchial epithelium into airways Airways become narrower and occlude Disruption of the ciliated epithelial cells (which transport mucous out of the airways and into the pharynx, to be swallowed or evacuated) ↓ mucous clearance from airways Excess airway mucous triggers cough reflex Cough Interstitial edema Nasal Congestion Air is absorbed distal to occlusion (gas trapping) When all air is absorbed, alveoli collapse (resorptive atelectasis) ↓ gas exchange between blood and air in remaining alveoli ↓ O2 saturation & ↑ CO2 content of blood Narrower airways, especially during expiration, causes audible turbulent airflow Wheeze on auscultation Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-Published November 29, 2020 on www.thecalgaryguide.com

mrna-vaccines-against-coronavirus-disease-2019-covid-19-production-and-mechanism-of-action

mRNA Vaccines against Coronavirus Disease 2019 (COVID-19): Production and Mechanism of Action Vaccine Production The “spike protein” is known to be a major viral surface Authors: Ryan Brenneis, Yan Yu* Reviewers: Davis MacLean, Hannah Yaphe, Timothy Fu, Stephen Vaughan* * MD at time of publication References 1. ACS Nano 2020, 14, 10, 12522–12537, Publication Date: October 9, 2020, https://doi.org/10.1021/acsnano.0c07197 2. NEJM 2020, Publication Date: December 10, 2020, DOI: 10.1056/NEJMoa2034577 3. Expert Review of Vaccines 2017, 16, 9, 871-881, Publication Date: 2017, DOI: 10.1080/14760584.2017.1355245 4. NEJM 2020, 383, 2439-2450, Publication Date: December 17, 2020, DOI: 10.1056/NEJMoa2027906 5. NEJM 2020, 383, 2427-2438, Publication Date: December 17, 2020, DOI: 10.1056/NEJMoa2028436 6. BMJ 2000, 321, 7271, 1237-1238, Publication Date: November 18, 2000, DOI: 10.1136.bmj.321.7271.1237 Notes: SARS-CoV-2 (RNA virus causing COVID-19) collected from an infected patient (ie. with a nasopharyngeal swab) Various reagents are added to the sample containing both human cells and viral constituents Reagents cause cell/viral membrane lysisàspilling cell contents, viral particles, and viral RNA Fats, proteins, and carbohydrates removed through various washing reagents, leaving nucleic acids (like RNA) Reverse transcriptase polymerase chain reaction produces complementary DNA (cDNA) from viral RNA cDNA library allows for SARS-CoV-2 genome to be mapped through whole-genome sequencing technology SARS-CoV-2’s spike protein DNA sequence is identified, and is used as a template to create synthetic viral spike protein mRNA Extra RNA bases are added to this mRNA strand to promote its stabilityàresulting RNA strand is now called “nucleoside-modified RNA” (“modRNA”) antigen (substance that elicits an immune response) from studies of other coronaviruses (e.g. SARS- CoV-1 and MERS-CoV) Pfizer/BNT162b2 vaccine contents: Moderna mRNA-1273 vaccine: Note: Lipid nano- particles are spherical hollow “balls” made of an outer lipid membrane plus other emulsifiers and membrane stabilizers. Lipid nanoparticles are capable of engulfing smaller molecules (like RNA) and merging with normal cell membranes Spike protein modRNA is then isolated (using a series of precipitation, extraction, and chromatography methods) Final modRNA lipid nanoparticle vaccine is now created and ready for intramuscular injection The modRNA vaccine is injected intramuscularly into a healthy person 2nd dose after 3-4 weeks needed to strengthen the immune response (to a level exceeding the immune response in patients recovered from Covid-19), boosting vaccine efficacy especially in older individuals4,5 Lipid nanoparticle fuses with human cells’ phospholipid membranes via endocytosis, releasing modRNA into the cell’s cytosol modRNA is translated by human ribosomes naturally found in the cell’s cytosol, producing viral spike protein components • • Foreign substance can cause local tissue inflammation The spike proteins encoded by the modRNA of each of the two vaccines are similar It is the proprietary lipid nanoparticle formulation (unknown to the public) that is unique to each vaccine Pain, redness, swelling at injection site (Transient) Proprietary Pfizer/ BioNTech lipid nanoparticle The modRNA encodes a full-length spike protein modified with two proline amino acids (for stability and immunogenicity)2 The modRNA encodes a full-length spike protein modified with two proline amino acids (for stability)1 Proprietary Moderna lipid nanoparticle Encapsulating this modRNA within Pfizer/ BioNTech’s lipid nanoparticle creates the 162b2 vaccine This specific formulation requires colder storage temperatures (-700C) Encapsulating this modRNA within Moderna’s lipid nanoparticle creates the mRNA-1273 vaccine This specific formulation can be stored at slightly warmer temperatures (-200C) Muscles are preferred injection sites as they have greater blood supply than other body tissues Vaccine Action Able to bring in immune cells faster to process foreign antigens6 Able to drain away foreign vaccine material fasterà minimizing local reactions6 Cell-mediated Immunity Spike protein degraded by intracellular enzymes into fragments Humoral Immunity Natural cellular processes release spike protein components from the cell into the bloodstream Spike protein components are engulfed by antigen presenting cells (dendritic cells, B cells, macrophages), fragmented, & bound to unique MHC Class II proteins MHC Class II proteins bring spike protein fragments to the antigen presenting cell’s surface, to present them to circulating naïve CD4+ (helper) T cells Some naïve helper T cells are able to successfully bind to the spike protein-MHC Class II protein complexes Binding activates these spike-protein specific helper T cells Spike protein fragments bound by MHC Class I proteins MHC Class I proteins bring spike protein fragments to the human cell surface MHC Class I proteins present spike protein fragments to naïve CD8+ T cell Naïve CD8+ T cells that able to bind to the spike protein-MHC Class I protein complex become activated, and travel to the lymphatic system to mature MHC = Major Histocompatability Complex; cell surface proteins key to immune function CD = Cluster of Differentiation; glycoproteins on T cell surfaces that are co-receptors and facilitate T cell binding to antigens/MHC complexes. They also distinguish the types of T cells. Some of these T-Cells mature into cytotoxic T cells that now recognize the viral spike protein Cytotoxic T-cells bind to human cells infected with SARS-CoV-2 expressing spike protein or spike protein fragments Cytotoxic T cell releases enzymes perforating infected cell, causing cell death to occur Immune system identifies and destroys human cells infected with SARS-CoV-2, slowing viral spread Other T cell’s can mature into memory T cells (stimulated by cytokines released by helper T cells) Memory T cells travel to lymphatic tissue, awaiting activation from future exposure to spike protein More rapid cell-mediated immune response to future SARS-CoV-2 infection (immunity) Activated helper T cells specific to the viral spike protein secrete cytokines to stimulate immune activity Systemic cytokine releaseàsystemic reactions like fever, chills, fatigue, myalgias (Transient) Some B cells mature into plasma cells that produce IgG antibodies against the viral spike protein Antibodies to spike protein mark SARS-CoV-2, allowing immune system to destroy virus Eradication of SARS-CoV-2 in extracellular compartments Activated helper T cell interacts with naïve B cells in lymphatic tissue Some B cells mature into memory B cells specific to SARS-CoV- 2 spike protein Future exposure to spike protein re-activates memory B cell in lymphatic tissue & creates plasma cells, producing antibodies more rapidly Rapid humoral immune response to future SARS-CoV-2 infection (immunity) Legend: Pathophysiology Mechanism Sign/Symptom/Clinical Finding End Result Published December 19, 2020 on www.thecalgaryguide.com

Adenovirus-Vector-Vaccines-Against-COVID19-Production-and-Mechanism-of-Action

Adenovirus Vector Vaccines Against COVID-19: Production and Mechanism of Action Johnson & Johnson Adenovirus type 26 (Ad26), a mild human adenovirus, is isolated Previous exposure to Ad5 or Ad26 may have sensitized immune system to the adenovirus vector1 Potential for human adenovirus vaccine to fail due to previous exposureàimmunity not built against spike protein CanSino Adenovirus type 5 (Ad5), a mild human adenovirus, is isolated Oxford/AstraZeneca Chimpanzee adenovirus AZD1222 (ChAdOx1), previously shown to be safe & to elicit an immune response in humans2, is isolated Vaccine Production SARS-CoV-2 (virus causing COVID-19) synthetic DNA library sequenced from viral RNA using reverse transcriptase polymerase chain reaction and whole genome sequencing technology Spike protein DNA sequence isolated from SARS-CoV-2 genome A promoter sequence is added to the spike protein DNA sequence, allowing human RNA polymerase to recognize and transcribe the spike protein DNA when introduced into human cells Recombinant genetic technology inserts the modified spike protein DNA into a plasmid: a circular piece of DNA that acts as a shuttle allowing for the insertion of new genes (such as the spike protein gene) into host genomes (like the adenovirus vector DNA genome) Adenoviral DNA isolated using various lytic & washing reagents (chemicals that break open cell membranes and remove non- nucleic acid cellular materials) Adenoviral DNA sequenced using whole genome sequencing, then modified as follows: Chimpanzee virus negates possibility of previous immunity to the viral vector1 Chimpanzee viral vector more likely to successfully generate immune response to the spike protein E1 region of adenoviral genome E3 region of adenoviral genome deleted to create deleted to block viral replication3 room for insertion of SARS-CoV-2 spike protein DNA3 Adenovirus used in the final vaccine cannot replicate within human cells and cannot cause human disease References 1. ACS Nano 2020, 14, 10, 12522–12537, Publication Date: October 9, 2020, https://doi.org/10.1021/acsnano.0c07197 Modified adenoviral DNA genome is reinserted into The viral vector & the spike protein plasmid are mixed together, and DNA recombination the adenovirus particle, creating the “viral vector” technology inserts the spike protein gene from the plasmid into the adenovirus DNA2 Adenovirus containing transcribable SARS-CoV-2 spike protein DNA is introduced into a special cellular culture, allowing the virus to replicate despite its modified DNA2, 3 Authors: Ryan Brenneis, Yan Yu* Reviewers: Davis MacLean, Hannah Yaphe Stephen Vaughan* * MD at time of publication 2. Nature 2020, 586, 578–582, Publication Date: October 20, 2020, https://doi.org/10.1038/s41586- 020-2608-y 3. Frontiers in Immunology 2018, 9, 1963, Publication Date: September 19, 2018, doi: 10.3389/fimmu.2018.01963 4. NPJ Vaccines 2020, 5, 69, Publication Date: July 27, 2020, doi: 10.1038/s41541-020-00221-3 5. The Lancet 2020, Publication Date: Dec. 8, 2020, https://doi.org/10.1016/S0140-6736(20)32623-4 6. BMJ 2000, 321, 7271, 1237-1238, Publication Date: November 18, 2000, DOI: 10.1136.bmj.321.7271.1237 7. NEJM 2021, Publication Date: Jan. 13, 2021, DOI: 10.1056/NEJMoa2034201 Adenovirus containing transcribable SARS-CoV-2 spike protein DNA is isolated and concentrated to a high enough level for administration as a vaccine Adenoviruses have an outer protein layer (called a capsid) to protect its DNA DNA is more stable than mRNA due to deoxyribose sugar backbone and intermolecular bonds between strands Enhanced stability compared to mRNA lipid nanoparticle vaccines Can be stored at 2-8°C for up to 3-6 months Muscles are preferred injection sites as they have greater blood supply than other body tissues Immune cells arrive faster to The viral vector vaccine is injected intramuscularly into a healthy person process foreign antigens6 Foreign substance can cause local tissue inflammation Pain, redness, swelling at injection site (Transient) Note: The Johnson and Johnson vaccine may be 90% effective after a single dose7 Foreign vaccine material drains away fasterà minimizing local reactions6 2nd dose after 28 days recommended to strengthen the immune response (to a level exceeding the immune response in patients recovered from Covid-19), boosting vaccine efficacy especially in older individuals5 Vaccine Action Cell-mediated Immunity Spike protein degraded by intracellular enzymes into fragments Adenovirus surface antigens interact with human cellular receptors, allowing viral entry into human cell via endocytosis3 Adenovirus vector travels to cell nucleus, merges with nuclear envelope and injects its DNA (including the spike protein DNA) into the nucleus RNA polymerases in the nucleus transcribe the viral DNA, making messenger RNA (mRNA) for SARS-CoV-2 spike protein mRNA is transported back into the cytosol & translated by ribosomes naturally found there, producing full length SARS-CoV-2 spike protein Humoral Immunity Natural cellular processes release spike protein components from the cell into the bloodstream Spike protein components are engulfed by antigen presenting cells (dendritic cells, B cells, macrophages), fragmented, & bound to unique MHC Class II proteins MHC Class II proteins bring spike protein fragments to the antigen presenting cell’s surface, to present them to circulating naïve CD4+ (helper) T cells Some naïve helper T cells are able to successfully bind to the spike protein-MHC Class II protein complexes Binding activates these spike-protein specific helper T cells Spike protein fragments are bound by MHC Class I proteins MHC Class I proteins bring spike protein fragments to the human cell surface MHC Class I proteins present spike protein fragments to naïve CD8+ T cell Naïve CD8+ T cells that able to bind to the spike protein-MHC Class I protein complex become activated, and travel to the lymphatic system to mature3 MHC = Major Histocompatability Complex; cell surface proteins key to immune function CD = Cluster of Differentiation; glycoproteins on T cell surfaces that are co-receptors and facilitate T cell binding to antigens/MHC complexes. They also distinguish the types of T cells. Some of these T cells mature into cytotoxic T cells that now recognize the SARS-CoV-2 spike spike protein Cytotoxic T cells bind to human cells expressing spike protein or spike protein fragments (e.g. future COVID-19 infection) Cytotoxic T cells release enzymes perforating infected human cells, causing cell death to occur Immune system can now more quickly identify & destroy human cells showing signs of COVID-19 infection Some T cell’s can mature into memory T cells (stimulated by cytokines released by helper T cells) Memory T cells travel to lymphatic tissue, awaiting activation from exposure to spike protein in the future More rapid cell-mediated immune response to future SARS-CoV-2 infection (immunity) Activated helper T cells specific to the viral spike protein secrete cytokines to stimulate immune activity Systemic cytokine releaseàsystemic reactions like fever, chills, fatigue, myalgias (Transient) Note: Duration of cellular/ humoral immunity is unknown Some B cells mature into plasma cells that produce IgG antibodies against the viral spike protein Antibodies to spike protein mark SARS-CoV-2, allowing immune system to destroy virus Eradication of SARS-CoV-2 in extracellular compartments Activated helper T cell interacts with naïve B cells in lymphatic tissue Some B cells mature into memory B cells specific to SARS-CoV- 2 spike protein Future exposure to spike protein re-activates memory B cell in lymphatic tissue & creates plasma cells, producing antibodies more rapidly Rapid humoral immune response to future SARS-CoV-2 infection (immunity)3 Legend: Pathophysiology Mechanism Sign/Symptom/Clinical Finding End result Published February 11, 2021 on www.thecalgaryguide.com

Potassium-Sparing-Diuretics-Mechanism-of-Action-and-Side-Effects

Potassium-Sparing Diuretics: Mechanism of Action and Side Effects Potassium-Sparing Diuretics Authors: Samin Dolatabadi, Yan Yu* Reviewers: Jessica Krahn, Timothy Fu, Juliya Hemmett* * MD at time of publication Epithelium Sodium Channel Blockers (Amiloride and Triamterene) Inhibit Na+ channels (involved in Na+ reabsorption) in the luminal membrane of the principal cells in the cortical collecting duct Aldosterone Antagonists (Spironolactone and Eplerenone) Competitively blocks mineralocorticoid receptors and ↓ aldosterone effect in the renal tubules and throughout the body ↓ aldosterone effectà↓ expression of basolateral Na+/K+ pumps & luminal epithelium Na+ channels on the principal cells of cortical collecting duct Spironolactone’s molecular structure is similar to that of steroid hormonesàspironolactone can also block androgen receptors Anti-androgenic effects (due to ↓ androgen function in reproductive organs, skin, and on brain centers) Triamterene can form triamterene crystals and granular casts (unclear mechanism) ↓ Na+ reabsorption by principal cells ↓ in serum Na+ concentration: Hyponatremia ↓ K+ pumped out into the tubule by principal cells Crystals & casts obstruct tubular lumen → inflammation (unclear mechanism) Triamterene crystals are directly cytotoxic to tubular cells Only ~2-5% of Na+ filtered by the glomerulus is normally reabsorbed in the cortical collecting ductàthe ↑ in Na+ retained in cortical collecting duct is mild Water follows Na+ to maintain a balanced osmotic pressureà↑ in water in cortical collecting duct available for excretion ↑ positive charges in lumen relative to surroundings generates an electropositive tubular lumen Unfavorable electrical gradient ↓ secretion of positive charged ions into electropositive lumen ↓ libido Menstrual abnormalities (in women) ↓ acne Gynecomastia (in men) ↓ secretion of K+ ↑ in serum K+ concentration: Hyperkalemia Cardiac Arrythmias (See relevant slide on Hyperkalemia: Clinical Findings) Interstitial inflammation and tubular injury Drug-induced Nephrotoxicity Mild Diuresis ↓ blood volume ↓ Blood pressure/ Hypotension ↓ secretion of H+ ↑ in serum H+ concentration: Metabolic Acidosis Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published February 15, 2021 on www.thecalgaryguide.com

AAA-Pathogenesis

Abdominal Aortic Aneurysm (AAA): Pathogenesis Different parts of the aorta have different embryologic origins Atherosclerosis Hypertension Age > 65 Progressive deterioration of aorta structural integrity over life span Connective Tissue Disease Structurally abnormal protein or protein organization in aorta Autoimmunity Infection (e.g Chlamydia, Mycoplasma pneumoniae, Helicobacter pylori, human cytomegalovirus, herpes simplex virus) Antigens (substance that causes immune response) on virus or bacteria resemble local proteins in abdominal aorta Antibodies produced in response to infection inappropriately target host cells in the aorta Antibodies tag cells in the abdominal aorta for destruction by T-lymphocytes Immune-mediated destruction of aorta Smoking Genetics Unclear mechanisms Subacute (not clinically detectable) inflammation of aortic tissue Inflammatory cytokines are released and immune cells are recruited ↑ pressure on aorta and other vessel walls Infiltration of vessel wall by lymphocytes and macrophages Production of enzymes that break down elastin & collagen proteins (which provide most tensile strength to aorta) Aorta susceptible to damage Degradation of aortic connective tissue Biomechanical stress on vessels Authors: Olivia Genereux Davis Maclean Reviewers: Jason Waechter* Amy Bromley* Yan Yu* *MD at time of publication The exact mechanisms are complex, debatable, and an area of intensive research – the 3 mechanisms and associated pathophysiology presented here are generally thought to be the main causes of abdominal aortic aneurysms Infrarenal aorta has poorly developed vaso vasorum (dedicated blood supply to vessel wall) Infrarenal aorta relies solely on nutrient diffusion from aortic blood that crosses abdominal aorta Infrarenal aortic wall has fewer “lamellar” units (fibromuscular units) than other regions of the aorta Infrarenal aorta is less elastic & less able to distribute stress Loss of smooth muscle cells & thinning of tunica media Destruction of elastin in tunica media Normal layers of the aortic wall ↓ aortic tensile strength (ability to withstand stretching) Aorta expands and dilates due to internal pressure Tunica Intima (inner-most tissue layer of aorta) Tunica Media (layers of elastic tissue (elastin) and muscle fibers) Adventitia (thin outermost collagenous layer) (longitudinal section) Aortic aneurysms are usually infrarenal (85%) Abdominal Aortic Aneurysm Infrarenal aorta more prone to ischemia and has impaired repair potential Abnormal, irreversible dilation of a focal area of abdominal aorta (area of aorta between diaphragm & aortic bifurcation) to twice the diameter of adjacent normal artery segment Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-Published February 27, 2021 on www.thecalgaryguide.com

Cubital-Tunnel-Syndrome-Ulnar-Neuropathy

Cubital Tunnel Syndrome (Ulnar Neuropathy): Pathogenesis and clinical findings Osteoarthritis Rheumatoid arthritis Diabetes mellitus (see Calgary Guide slide on Diabetic Neuropathy) Degenerative bone & joint changes Autoimmune damage to joints Abnormal bone structure/lesions Idiopathic Hyperglycemia causes nerve damage (complex mechanisms) Elbow trauma Repetitive elbow flexion Authors: Chris Oleynick Alexandros Mouratidis Yan Yu* Reviewers: Annalise Abbott Sean Crooks Davis Maclean Hannah Koury Jeremy LaMothe* Ian Auld* * MD at time of publication Inflammation or edema in cubital tunnel (space between medial epicondyle of humerus and olecranon of ulna) where ulnar nerve is found ↓ size of the cubital tunnelà↑ pressure on internal contents (e.g. ulnar nerve) Axonal conduction is interrupted Myelin sheath is damaged ↓ blood supply to nerve Weakness of adductor pollicus longus (works to adduct thumb) ↑ compensatory activity of flexor pollicis longus with pinching ↓ activity of hypothenar muscles (which move the 5th digit) ↓ activity of 5th digit palmar interosseus muscles (which adduct the 5th digit) Cubital Tunnel syndrome: compression neuropathy Paresthesia Abnormal sensations of skin (“pins & needles”, tingling, burning, and/or numbness) in ulnar nerve sensory distribution ulnar nerve ↓ activity of muscles innervated by ulnar nerve (medial forearm flexors, hypothenar muscles, interossei muscles, adductor pollicis longus) + Tinel sign over cubital tunnel (tapping at medial elbow causes discomfort and/or paresthesia) Weak pinch & ↓ grip strength + Froment’s sign (thumb hyperflexion compensates for weak pinch) Hypothenar atrophy + Wartenburg’s sign (involuntary, excess abduction of 5th digit) of the Altered sensation in areas innervated by ulnar nerve (medial forearm and wrist, 5th digit, and medial half of 4th digit) + elbow flexion test (flexing elbow & extending wrist further ↓ volume of the cubital tunnelà paresthesia in ulnar nerve sensory distribution Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications First published January 12, 2017, re-published February 28, 2021 on www.thecalgaryguide.com

Achilles-Tendon-Rupture

Achilles Tendon Rupture: Pathogenesis and Clinical Findings Achilles tendon ruptures are multifactorial, and may arise from any one or combination of the factors below Authors: Alyssa Federico, Joseph Kendal Reviewers: Davis Maclean, Hannah Koury , Amanda Eslinger, Maninder Longowal, Dave Nicholl, Mehul Gupta, Gerhard Kiefer*, Yan Yu*, Jeremy LaMothe* * MD at time of publication Aging Iatrogenic factors E.g. use of fluoroquinolone antibiotics,or local or systemic corticosteroids Exact mechanisms remain unclear Exercise related factors Vascular compromise Any process that impairs blood flow to the Achilles tendon (e.g. peripheral artery disease) Impaired ability to heal from microtrauma Mechanical factors Abnormal biomechanics: bowleg, flatfoot, excessive supination, obesity, change in terrain Participation in vigorous exercise Excessive heat generation (hyperthermia) in Achilles tendon induces changes in the extracellular matrix Intra-tendinous collagen degeneration, disorientation, and thinningàcompromised Achilles tendon integrity Sudden shear stress and high tension in an already weakened Achilles tendon, stretching it beyond its capacity Haglund’s deformity: enlargement of the calcaneal postero- superior tuberosity Bony enlargement rubs on soft tissue and causes inflammation of Achilles tendon ↓ tendon strength from changes in extracellular matrix Episodic participation or sudden ↑ in exercise Irregular use renders Achilles tendon weaker Microtrauma to the and less flexible Achilles tendon on Achilles Tendon Abnormal loading Sudden, forced dorsiflexion of foot Eccentric contraction of the gastrocnemius-soleus complex The gastrocnemius muscle normally attaches to Achilles tendon to control plantar flexion of the foot With the Achilles tendon ruptured, contraction of the gastrocnemius muscle cannot induce plantar flexion Achilles tendon rupture Achilles tendon innervated by the sural nerve and tibial nerve Pain over rupture site (e.g. “like being kicked in the back of the leg”) Antalgic gate: abnormal gait developed to avoid pain while walking High tension at the origin and insertion points of the tendon causes the ends of the tear to separate The Achilles tendon contains blood vessels. Rupturing the tendon also ruptures the blood vessels withinàblood leaks out into tendon rupture site Bruising and swelling over rupture site ↓ resting ankle plantar flexion (Observed in prone position with knees flexed at 90 degrees) Passive contraction (e.g. squeezing) of the gastrocnemius does not cause plantar flexion + Thompson (calf squeeze) test Weak ankle plantar flexion Lack of push-off in gait Audible “pop” at time of injury Palpable gap between rupture ends Difficulty ambulating ↓ muscle use over time Calf atrophy Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-Published March 21, 2021 on www.thecalgaryguide.com

Thyroïdite

Thyroïdite : Pathogénie et résultats cliniques Authors: Jaye Platnich Reviewers: Matthew Harding Mark Elliott Hanan Bassyouni* * MD at time of publication Hypertrophie ferme et diffuse de la glande thyroïde (douloureuse dans le cadre d'étiologies subaiguë, radique et infectieuse) Symptômes généraux de l’hyperthyroïdie Post-natal Médicaments/ Radiation Thyroïdite bactérienne Subaigüe (post-virale) Abbréviations: • TSH- Hormone stimulant de la thyroïde Inflammation de la glande thyroïde Plusieurs méchanismes Brianna Ghali Sylvain Coderre* Phillippe Couillard* Translator: Infiltration de la glande thyroïde avec des globules blancs Destruction immunitaire de la glande thyroïde ↑ libération de T4 et T3 stockés par glande thyroïde endommagée durant 2-6 semaines (phase hyperthyroïde) ↓ sécrétion de T4 et T3 de la glande thyroïde endommagée durant des semaines-mois (phase hypothyroïde) Souvent une résolution à un état euthyroïde (normal), mais peut aussi rester dans un état hypothyroïde ↑ T4/T3 inhibe la libération de la TSH par la ↓ sécrétion TSH Réaction inflammatoire altère la fonction folliculaire normale (production T4/T3 et importation d’iode) glande pituitaire ↓ Absorption de l'iode par la glande thyroïde ↓ Capture de l'iode radioactif à la scintigraphie de médecine nucléaire Plusieurs méchanismes Symptômes généraux de l’hypothyroïdie ↓ T4/T3 stimule la liberation de la TSH par la ↑ sécrétion TSH Dommage altère la fonction folliculaire normale, (production T4/T3 et importation d’iode) glande pituitaire ↓ Absorption de l'iode par la glande thyroïde ↓ Capture de l'iode radioactif à la scintigraphie de médecine nucléaire Légende: Pathophysiologie Méchanisme Signes/Symptômes/Résultats labo Complications Publié June 19, 2013 on www.thecalgaryguide.com

Fat-Embolism-Syndrome

Fat Embolism Syndrome: Pathogenesis and clinical findings Panniculitis (conditions causing inflammation of subcutaneous fat) Non-trauma related (rare) Long bone fracture Pelvic fracture Orthopedic Trauma Intraosseous access Soft tissue injuries Chest compressions Bone marrow transplant Pancreatitis Diabetes mellitus Fat from bone marrow is disrupted and leaks into bloodstream via damaged blood vessels Fat globules obstruct dermal capillaries Capillaries rupture Blood leaks into the skin Petechial rash Non-Orthopedic Trauma (less common) Fat from injured adipose tissue is released from adipocytes into bloodstream Metabolic disturbance mobilizes stored fat and moves it into circulation Fat Embolism Syndrome the presence of fat globules in circulation Fat globules damage blood vessel walls Platelets stick to damaged areas Platelet aggregation ↑ circulating free fatty acids ↑ inflammatory cytokines (TNF, IL1, IL6) ↑ serum C Reactive Protein (an acute phase reactant) C reactive protein binds to lipid vesicles in circulation ↑ formation of lipid complexes in the blood Obstruction of cerebral vasculature ↓ blood flow and oxygen delivery to brain tissue Neurological findings: ranging from ↓ level of consciousness to seizures Notes: Large quantities of fat globules can obstruct pulmonary vasculature Blood clots form throughout the body Disseminated intravascular coagulopathy Back up of blood into right heart àRight ventricular dysfunction ↓ pulmonary arterial blood flow à↓ gas exchange in the lungs Higher CO2 & lower O2 levels in blood àdetected by chemoreceptors Chemoreceptors stimulate respiratory centre in the brain to ↑ rate of respiration Dyspnea / Tachypnea Authors: Tabitha Hawes Reviewers: Hannah Koury, Alyssa Federico, Davis MacLean, Mehul Gupta, Yan Yu*, Jeremy Lamothe* * MD at time of publication • Underlined findings indicate classic triad of symptoms (petechial rash, neurologic findings, dyspnea/tachypnea) • Clinical presentation of fat embolism syndrome is variable and may present with any or all of these findings ↓ pumping of blood into systemic circulation Hypotension Obstructive shock Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published July 19, 2021 on www.thecalgaryguide.com

Hypertriglycéridémie primaire

Hypertriglycéridémie primaire : Pathogénie et résultats cliniques Traduction: Brianna Ghali Philippe Couillard* Autheur: Gillian Goobie Rédacteurs: Peter Vetere Yan Yu Hanan Bassyouni* * MD au moment de la publication Acronymes: LPL = lipoprotéine lipase TG = triglycérides CM = chylomicrons LDL = lipoprotéine de basse densité VLDL = lipoprotéine de très basse densité FFA = acides gras libres CV = cardiovasculaire MC=maladie coronarienne Déficit en lipoprotéine lipase (LPL) La LPL présente dans le cœur, les muscles squelettiques, les tissus adipeux et d'autres tissus est incapable d'éliminer les TG des CM et des VLDL. Hyperlipidémie combinée familiale Surproduction de TG-riches VLDL, LDL et/ou ApoB100 Dysbétalipoprotéinémie familiale Mutation de ApoE (l'apoprotéine responsable de l'élimination des CMs et VLDLs de la circulation) VLDLs & CMs riches en TG s’accumulent dans le sang Hypertriglycéridémie Primaire versus Secondaire: - L'hypertriglycéridémie primaire est due à une cause génétique. -L'hypertriglycéridémie secondaire est due à une cause médicale ou à un mode de vie acquis. Mécanismes inconnus du risque ↑ CV, distincts du risque d'athérosclérose associé à l'hypercholestérolémie. MC Prématurée (âge d'apparition avant 50 ans chez les hommes et 55 ans chez les femmes) Remarque : les signes les plus pathognomoniques de l'hypertriglycéridémie sont les xanthomes éruptifs et la lipémie rétinienne. La diffusion de la lumière par les TG sanguins fait paraître les vaisseaux de la rétine blanc au fond d’oeil Lipemia Retinalis La lipase pancréatique libère les FFA des CM et des VLDL. La concentration plasmatique des FFA dépasse la capacité de fixation de l'albumine. Les AGF s'accumulent dans le pancréas, provoquant une inflammationàla lyse des cellules pancréatiques et la libération d'enzymes digestives pancréatiques. Pancréatite (le risque de pancréatite augmente considérablement avec un taux de TG >10mmol/L) Des niveaux excessifs de CM et de TG traversent les vaisseaux sanguins pour atteindre le derme ou la cornée. TGs engloutis par les macrophages dermiques or cornéens (histiocytes) Xanthomes éruptifs (papules jaunes de 1 à 3 mm généralement observées sur les tendons et surfaces d'extension comme les coudes, les genoux, les fesses, ainsi que sur le dos, la poitrine et les extrémités proximales). Légende: Pathophysiologie Méchanisme Signe/Symptôme/Résultat Laboratoire Complications Publié 19 juin 2013 à www.thecalgaryguide.com

Dry-Eye-Syndrome-Pathogenesis

Dry Eye Syndrome (Keratoconjunctivitis sicca): Pathogenesis The Pathophysiology of Dry eye disease is complex and an area of active investigation – The mechanism and causes presented here represented the highest yield causes and mechanism for students Post laser eye surgery Disruption of corneal nerves ↓ corneal sensitivity Damage to trigeminal nerve, the sensory innervation of the eye (due to: Herpes Zoster, tumor, trauma, etc) Blepharitis (eyelid inflammation) Many medications can cause dry eye via multiple mechanisms presented here (e.g. ↓ corneal sensitivity, Meibomian gland dysfunction, lacrimal gland atrophy) Sex Hormones (e.g. androgens & estrogens) play a complex and poorly understood role in mediating dry eye disease (net effect is that women are more often affected by dry eye) Obstructed meibomian glands Eyelid damage Gland atrophy These items represent general causes of meibomian gland dysfunction – exact causes are numerous, their pathophysiology is beyond the scope of this slide Contact lens (long term use) Corneal nerve adaptation to chronic mechanical stimulation Autoimmune disease (e.g. Sjögren's syndrome) Chronic inflammatory infiltration of the lacrimal gland (and salivary gland) Autoimmune Lymphocytic infiltration Inflammatory cytokine release Autoantibody production Cell death and apoptosis Lacrimal gland degeneration Meibomian gland dysfunction (Located along the eyelid margins, these glands produce meibum, an oily substance that prevents evaporation of the tear film) ↓ meibum secretion Loss of lipid layer covering the eye, ↓ the barrier that blocks evaporation of tear film Tear Film instability Lifestyle Extended reading or TV or electronic device uses Exposure Keratopathy (any condition causing dryness due to incomplete or inadequate eyelid closure, e.g. Bell’s Palsy) ↓ activity of the afferent portion of corneal reflex arc (responsible for reflex tearing: tearing in response to irritation of the eye) Mechanical damage to goblet cells secrete mucins – a substance that lubricates the eye and preserves tear film ↓ blink rate ↑ time and area ↓ normal reflex tearing for evaporation Dry climate Wind exposure Infiltrative diseases (e.g. sarcoidosis) Lacrimal gland infiltration ↓ Lacrimal gland secretion of the the watery aqueous layer of the tear film (Aqueous deficient dry eye) Deficient or unstable tear film (Evaporative dry eye) ↑ tear evaporation Direct damage to lacrimal gland (e.g. infection or trauma of the eye) Authors: Davis Maclean, Yan Yu*, Michael Penny, O.D. Reviewers: Natalie Arnold, Saleel Jivraj, O.D., Adam Muzychuk*, Victor Penner* *MD at time of publication Hyperosmolar Tear Film (hyperosmolarity = ↑ solutes and ↓ solvent) (Further) Tear Film instability Corneal and conjunctival epithelial cells dry out, including goblet cells (which secrete mucins – a substance that lubricates the eye) Inflammatory immune response àRecruitment and activation of CD4+ (Helper) T-Cells, further produce cytokines Further irritation and damage to ocular surface structures (cornea, conjunctiva and Meibomian glands) and lacrimal glands See Calgary Guide: “Dry Eye Syndrome (Kerato- conjunctivitis sicca):Clinical Findings” for signs and symptoms Dry Eye Syndrome (Keratoconjunctivitis sicca): A multifactorial disease of the ocular surface and tears characterized by loss of tear film homeostasis, tear film hyperosmolality and inflammation Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published August 7, 2021 on www.thecalgaryguide.com

Dry-Eye-Syndrome-Clinical-Findings

Dry Eye Syndrome (Keratoconjunctivitis sicca): Clinical Findings If dry eye is chronic or severe (e.g Sjögren’s syndrome) corneal ulcerations or scarring may occur Impaired visual acuity/ Blindness (does not improve with lubrication) See Calgary Guide: “Dry Eye Syndrome (Keratoconjunctivitis sicca): Pathogenesis” for explanation of etiology and pathogenesis Dry Eye Syndrome (Keratoconjunctivitis sicca): Disease of the ocular surface and tears characterized by loss of tear film homeostasis, tear film hyperosmolality and inflammation Tear film instability & hyperosmolarity Ocular surface inflammation: Immune cell (specifically T-Cell) destruction of corneal and conjunctival epithelium ↓ quantity and/or quality of tear film Inflammatory factors vasodilate conjunctival vessels, making the eye look redder in appearance Conjunctival injection Red eye Corneal surface irregularities Light rays pass through disrupted tear film and ocular surface structures as they enter the eye Degraded image quality as light passes through the eye Impaired visual acuity (improves with lubrication) ↓ lubrication over the eye surface ↑ friction on the eye during blinking or when opening eyes after sleep May cause corneal abrasion (See Calgary Guide: Corneal Abrasion) ↑ stimulation of corneal and conjunctival nerve endings Irritation and damage to corneal and conjunctival cells ↑ stimulation of nerve endings Chronic inflammation surrounding corneal nerves in conjunctiva and epithelium can lead to decreased neuronal firing thresholds (Neurosensory dysfunction / hyperalgesia) ↑ activity of the afferent portion of corneal reflex arc (responsible for reflex tearing: tearing in response to irritation of the eye) Foreign body sensation (scratching / feeling as if a foreign body, like a grain of sand, is in the eye) Minor (typically non-painful stimuli) may cause pain due to hypersensitive corneal nerves Corneal neuropathic pain (pain not fully explained by ocular surface changes, often resistant to standard treatments, sometimes still present following ocular surface anaesthesia if central pathways affected) Pain with temperature change and wind exposure Exact mechanism unknown Photophobia Burning sensation Paradoxical reflex tearing (↑ tearing, which does not improve dry eye due to altered tear composition, poor surface coverage or overflow of temporary tearing out of the eye Authors: Michael Penny, O.D. Davis Maclean Yan Yu* Reviewers: Natalie Arnold Saleel Jivraj, O.D. Adam Muzychuk* Victor Penner* *MD at time of publication Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published August 6. 2021 on www.thecalgaryguide.com

epithelial-ovarian-cancer-pathogenesis-and-clinical-findings

Epithelial Ovarian Cancer: Pathogenesis and clinical findings Authors: Brian Yu Chieh Cheng, Yan Yu* Reviewers: Mehul Gupta, Hannah Yaphe, Sarah Glaze* * MD at time of publication See Epithelial Ovarian Cancer Risk Factors slide BRCA1 or BRCA2 mutationà faulty double strand DNA repairà↑ mutations & loss of controlled cell division Asymptomatic serous tubal intraepithelial carcinoma (STIC) lesions of the fallopian tube fimbria develop overtime STIC cells may break off from the fallopian tube & become trapped during inclusion cyst formation As part of the ovarian cycle, the coelomic epithelium (CE) of the ovary is ruptured & repaired after ovulation Incomplete repair of the CE results in invagination of the rupture site, forming a benign cortical inclusion cyst CE cells trapped during cyst formation undergoes metaplasia to tubal or other types of epithelium Endometriosis Endometriosis causes endometrial tissue to start growing on ovarian CE Endometrial cells trapped during cyst formation progresses to endometrioma or “chocolate cysts” Immune cell infiltration & cytokine release inside the ovary results in dysregulated inflammation Cancer cells proliferate in distant organs, invading & destroying native cells Organ failure Metastatic spread to liver, lung, brain & lymph nodes Lymphadenopathy Systemic immune activation ↑ metabolic consumption ↑ capillary surface area & permeability Fatigue & weight loss ↑ fluid entry into Ascites peritoneal cavity Further somatic mutation accumulation leads to malignant transformation of epithelium Tumor growth stimulates new blood vessel formation to supply itself with nutrients & O2 Omental / peritoneal seeding of cancer cells Early-stage disease Asymptomatic Epithelial Ovarian Cancer In late-stage disease, tumor may secrete a glycoprotein called mucin 16, also known as CA-125 (sensitive but non-specific biomarker for ovarian cancer) ↑ serum CA-125 levels Cancer cells proliferate inward & eventually ruptures the ovary Cancer cells are released into the peritoneal cavity Tumor growth in local organs (bladder/uterus) progresses to symptomatic cancer ↑ tumor volume & local tumor spread directly disrupts neighboring structures Pelvic/abdominal pain Palpable pelvic/abdominal mass Altered urinary frequency Compression of colon/bladder Change in bowel habits Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published August 15, 2021 on www.thecalgaryguide.com

COPD Acute Exacerbations

COPD Acute Exacerbations: Triggers and Signs/Symptoms Authors: Brianne McDonald, Yan Yu* Reviewers: Nilani Sritharan, Sean Doherty, Zihong Xie (谢梓泓), Zesheng Ye (叶泽生), Yonglin Mai (麦泳琳)*, Kerri Johannson* * MD at time of publication Notes: • The triggers for acute exacerbations of COPD are unknown in approximately 1/3 of cases • Changes in pulmonary function (e.g. FEV1) are poorly sensitive in the individual diagnosis of acute exacerbations of COPD due to individual variability Acute Bacterial Infection Activation of proinflammatory cytokines and recruitment of neutrophils Acute Viral Infection Epithelial cell secretion of cytokines and ↑ airway lymphocythemia Acute ↑ in airway inflammation (accumulation of inflammatory cells and release of harmful mediators, such as reactive oxygen species and proteases, into the lung tissue/airways) Air pollution (including cigarette smoke) ↑ reactive oxygen species in lungs Airway inflammation ↑ secretions that accumulate in the airway lumen Airway wall edema Limits outflow of air from lungs on expiration Airway bronchoconstriction in response to inflammation Constricted airways create audible turbulent airflow on expiration Systemic spread of inflammatory markers via the bloodstream cause inflammation throughout the body ↑ Cardiac Morbidity ↑ CRP Worsening of respiratory symptoms Irritation of cough reflexes in airways Cough ↑ Sputum production and sputum purulence ↑ Wheeze Unexpired air becomes trapped in the lungsàDynamic Hyperinflation Bloodflow to lungs continue to perfuse under- ventilated regions of lungs àV/Q Mismatch Lungs are larger àmore blood remains in lungs à↓ preload Acute Respiratory Failure Tachypnea ↑ Dyspnea Accessory Muscle Use Attempts to restore normal arterial CO2 and O2 levels Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published April 21, 2019, updated October 6, 2021 on www.thecalgaryguide.com

Hypercortisolemia

Hypercortisolemia (Cushing’s Syndrome): Clinical Findings Cortisol is a net catabolic hormone affecting many body systems, serving to release energy into the blood in response to stress. Excess cortisol also impacts circulation and impairs immune function. Excess Serum Cortisol affects: Authors: Samin Dolatabadi, Yan Yu* Reviewers: Meena Assad, Amanda Henderson, Brooke Fallis, David Campbell* * MD at time of publication Bone and Calcium Metabolism Kidney and vasculature Excess cortisol in the renal tubule saturates the enzyme 11β- HSD2, which converts cortisol to cortisone Capacity of body to convert cortisol to cortisone is exceeded Excess cortisol can mimic aldosterone and bind to mineralocorticoid receptors (cortisone can’t bind to these receptors) ↑ Aldosterone effect → ↑ Na+ reabsorption from the cortical collecting duct into blood vessels Liver and Peripheral Tissue Cortisol ↑ gluco- neogenesis in liver, and ↑ insulin resistance by body tissue (unclear mechanisms) Hyper- glycemia Reproductive System Cortisol exerts negative feedback on hypothalamus à↓ gonadotropin releasing hormone (GnRH) secretion ↓ GnRH → ↓ LH/FSH → ↓ estrogen and testosterone production (especially important in females) Infertility, ↓ Libido, Irregular Menses Adipose Tissue Cortisol ↑ fat breakdown (lipolysis) Selective expression of cortisol receptor on different adipose tissuesàcentral, facial, dorsal fat is less broken down than in other areas (mechanism unclear) Combined with cortisol ↑ appetite: Skin & Connective Tissue ↑ Serum cortisol à↓ Fibroblast proliferation → ↓ Collagen synthesis Skin atrophy with loss of connective tissue Muscle ↑ Proteolysis & ↓ Protein synthesisà↓ muscle growth and function Immune System Normal serum cortisol protects against damaging effects of uncontrolled inflammatory and immune responses ↑ Serum cortisolà over-suppression of inflammation and impaired cell- mediated immunity ↑ Serum cortisol leads to ↓ Intestinal Ca2+ absorption and ↓ renal Ca2+ reabsorption ↓ Serum Ca2+ ↑ PTH secretion ↑ Serum cortisolà↑ RANKL:OPG ratio ↓ Osteoblast activity & ↑ Osteoclast activity Cardiac muscle Cardio- myopathy, Heart Failure Skeletal muscle, especially upper arms & thighs (for unclear reasons) Proximal Muscle Weakness Easy Bruising ↑ abdominal size stretches the fragile skin to become thinneràvenous blood of the underlying dermis becomes visible Purple Striae If hypertension is chronic Ca2+ resorption from bone into the blood Osteoporosis Supraclavicular & Dorsal Fat Pads Central Obesity Poor Wound Healing Susceptibility to infection Round Face (Moon Face) Abbreviations: • RANKL – Receptor activator of nuclear factor kappa-Β ligand • OPG – Osteoprotegerin • 11β-HSD2 – 11β-hydroxysteroid dehydrogenase type 2 Water follows Na+ into blood vessels to balance the osmotic pressure between the blood and renal tubules Water reabsorption → Expansion of blood volume Hypertension Both primary Cushing’s (e.g. adenomas that extend into zona reticularis of the adrenal cortex) and central/secondary Cushing’s (e.g. ↑ ACTH stimulation of zona reticularis) are associated with ↑ adrenal androgen secretion Removal of positively charged Na+ from tubular lumen creates a negative luminal environment K+ follows the electrical gradient and is secreted into tubular lumen ↓ Serum K+ concentration Hypokalemia Arrhythmia, Paralysis, Cramps (see Hypokalemia: Clinical Findings slide) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published October 17, 2021 on www.thecalgaryguide.com Hirsutism, Acne

Acne Vulgaris Complications

Acne vulgaris: Complications Acne vulgaris Cutaneous inflammation caused by acne lesions True Scars Authors: Stephen Williams Reviewers: Mehul Gupta, Lauren Lee, Yan Yu*, Laurie Parsons* * MD at time of publication Elevated Acne Scars ↑ collagen exceeds collagen degradation Prostaglandins (PGE2), leukotrienes (LTC4, LTD4), and thromboxane A2 are released in response to inflammation Atrophic Acne Scars Collagen degradation and disordered deposition during healing Formation of round- rectangular depressions with defined edges Box Car Scar True scars with textural change, very slow autoresolution over time The pigmentary changes and true scar formation resulting from acne may be more psychologically distressing than the original acne lesions Healing processes favoring deposition of Type 1 & Type 3 collagen Proliferation beyond the borders of original acne lesion Keloid Formation Healing processes favoring deposition of Type 4 collagen Growth remains within the margins of acne lesion Hypertrophic Scar Formation Dermal inflammation: Due to disruption of basal cell layer, melanin released and trapped by macrophages in the dermis. Epidermal inflammation: ↑ melanin production and transfer of melanin to keratinocytes Microvascular dilatation and ↑presence of erythrocytes Erythematous macules appear where acne was present Post- inflammatory Erythema (PIE). More common in Fitzpatrick Skin Types I-III Formation of V- shaped tracts with sharp margins Ice Pick Scar Formation of a shallow edged depression layer anchored to dermal layer and subcutis Rolling Scar Pigmented macules or patches appear where acne was present Post-inflammatory Hyperpigmentation (PIH). More common in Fitzpatrick Skin Types III-VI No textural change, slow autoresolution over time True scars with textural change, do not resolve over time Psychosocial Concerns (Depression, Anxiety, Social Isolation) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published October 19, 2021 on www.thecalgaryguide.com

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS): Authors: Lauren D. Lee, Harry C. Liu* Reviewers: Mehul Gupta, Brian Rankin, Julia Chai, Stephen Williams Yan Yu* Laurie Parsons* *MD at time of publication Pathogenesis and clinical findings Genetic susceptibility Certain HLAs (e.g., HLA-B*58:01, HLA-B*57:01, and HLA-A*31:01) HLA alleles encode for MHC structure and may influence how specific drugs/drug metabolites interact with T cell receptors and MHC proteins on antigen-presenting cells Exposure to offending drug E.g., Aromatic anticonvulsants (lamotrigine, carbamazepine, and phenytoin), allopurinol, and sulfonamides Drug-specific CD4+ and CD8+ T cells produce tumor necrosis factor-alpha and interferon gamma ↑ activated T-cells 2-6 weeks after drug exposure Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) Latent Viral infection Latent viruses (HHV-6, HHV- 7, CMV, and EBV) concealed in regulatory T-cells Reactivation of latent viruses may be contributory or secondary to T cell activation by drugs Eosinophilia +/- atypical lymphocytes T helper type 2 cells recruit and activate eosinophils by releasing cytokines Activated leukocytes create a humoral immune and allergic response Dysfunction of regulatory T cells, resulting in failure to control unwanted immune responses against “self” Autoimmune processes with single- or multi-organ involvement CMV- Cytomegalovirus EBV- Epstein-Barr Virus HHV- Human Herpesvirus HLA- Human Leukocyte Antigens MHC – Major Histo- compatibility Complex Endocrine system mechanism of dysfunction unclear but may be linked to autoreactive T cells Autoimmune Type 1 thyroiditis diabetes Lymphadenopathy Fever Facial edema Liver lobular inflammation, dispersed foci of necrotic hepatocytes, granulomatous infiltrates consisting of eosinophils Hepatitis Kidney Interstitial edema and infiltrates of lymphocytes, histiocytes, eosinophils, and plasma cells Acute interstitial nephritis Lung increased pulmonary infiltrate and edema Morbilliform Skin Eruption Spongiosis Epidermal layer Dermal- Epidermal Junction Dermal layer Interface dermatitis Skin eruption (morbilliform to diffuse erythema with follicular accentuation) Interstitial pneumonitis Pleural effusion Eosinophilic infiltration Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published October 19, 2021 on www.thecalgaryguide.com

Vestibular Neuritis

Vestibular Neuritis: Pathogenesis and Clinical Findings Authors: Ryan Chan Jonathan Wong Reviewers: Mehul Gupta Davis Maclean Saud Sunba Yan Yu* Euna Hwang* * MD at time of publication Recent viral illness or upper respiratory tract infection Virus spreads along upper respiratory mucosa and into the inner ear structures Vestibular Neuritis Presumed idiopathic viral-induced inflammation of the vestibular nerve; typically unilateral Reactivation of Herpes Simplex Virus-1 in vestibular (Scarpa’s) ganglion Inflammatory cell infiltration leads to degeneration and atrophy of the vestibular nerve Superior Vestibular Neuritis (40-48%) Inflammatory cells traverse through only one long bony canal, easier for inflammatory cell infiltration Loss of afferent innervation from the superior and horizontal semicircular canal (SCC), utricle, and parts of the saccule Combined Superior Vestibular Neuritis and Inferior Vestibular Neuritis (34-56%) Inferior Vestibular Neuritis (1.3-18%) Inflammatory cells must pass through two separate bony canals, making inflammatory cell infiltration more difficult Loss of afferent innervation from the posterior semicircular canal (SCC) and saccule Utricular degeneration Displacement of otoliths/ otoconia (commonly into the posterior SCC) BPPV (can occur several months after onset of neuritis) Loss of horizontal SCC afferent neuron signaling to the brain Unilateral Loss or ↓ of normal nystagmus response to Caloric Testing (insertion of cold and warm water/air into the ear canal while supine) Loss of utricular afferent neuron signaling to the brain ↓ or absent Ocular Vestibular- Evoked Myogenic Potentials (VEMPs) and Normal Cervical VEMPs ↓ unilateral vestibular input to the brain leads to acute phase symptoms (over time, brain can compensate which allows for some symptom improvement) Loss of posterior SCC and saccular afferent neuron signaling to the brain ↓ or absent Cervical VEMPs, but Ocular VEMPs are normal ↓ or absent input to the ipsilateral vestibular nuclei elicits a vestibular nucleus response similar to contralateral SCC excitation Acute-Phase Spontaneous Nystagmus Fast phase beats away from the affected side (3- 10 days) And Loss of ocular fixation on Head Impulse Test ↓ or absent saccular input to the lateral vestibular nuclei (e.g., lateral vestibulospinal tract) results in the loss of lower limb postural adjustability Postural Instability (e.g., abnormal Romberg/sharpened Romberg, Fukuda step test) Bilateral mismatch of vestibular information to the brain Peripheral Vertigo (lasts several hours to days; rapid onset, severe, constant) Nausea and Vomiting Only the vestibular part of the vestibulo- cochlear nerve is affected, not the cochlear nerve No Hearing Loss or Tinnitus Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published October 19, 2021 on www.thecalgaryguide.com

COPD-发病机制

COPD: 发病机制 作者: Yan Yu 审稿人:Jason Baserman, Jennifer Au, Naushad Hirani*, Juri Janovcik* 译者: Zihong Xie (谢梓泓) 翻译审稿人:Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 /012 (如a1-抗胰蛋白酶缺乏) 阻止肺组织损伤的能力↓ +,-. (如长期吸烟、环境污染、感染) 肺内产生自由基 34*5 肺抗蛋白酶的失活 ↑氧化应激，炎性细胞因子，蛋白酶功能 支气管的持续、反复损伤 炎性细胞浸润， 杯状细胞增殖， 气道上皮纤毛 尤其中性粒细 黏液产生↑ 细胞死亡 气道弹性↓ (弹性回缩 肺实质的蛋白水解破坏↑ 维持气道开放 肺泡永久性异常 的结构支持↓ 扩张 胞 力) 肺气体潴留 气道狭窄与 肺过度 肺大泡 气道黏液潴留，成为感染 狭窄 病灶 塌陷 充气 肺气肿 (容易肺泡 破裂) 气道纤维化和 %&'()* 慢性阻塞性肺疾病(COPD) 临床表现 并发症 (参阅相关幻灯片) (参阅相关幻灯片) 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com COPD: Clinical Findings Lung tissue Chronic Obstructive Pulmonary Disease (COPD) damage ↓ elastic recoil to push air out of lungs on expiration Lungs don’t fully empty, air is trapped in alveoli (lung hyperinflation) ↑ lung volume means diaphragm is tonically contracted (flatter) If occurring around airways Airflow obstruction ↑ mucus production ↓ number of epithelial ciliated cells to clear away the mucus (the cells have been killed by airway inflammation) Chronic cough with sputum Author: Yan Yu Reviewers: Jason Baserman Jennifer Au Naushad Hirani* Juri Janovcik* * MD at time of publication During expiration, positive pleural pressure squeezes on airwaysà↑ obstruction ↓ ventilation of alveoli ↓ oxygenation of blood (hypoxemia) ↓ perfusion of body tissues (i.e. brain, muscle) Fatigue; ↓ exercise tolerance Total expiration time takes longer than normal Prolonged expiration More effort needed to ventilate larger lungs Respiratory muscles must work harder to breathe Turbulent airflow in narrower airways is heard on auscultation Expiratory Wheeze Diaphragm can’t flatten much further to generate deep breaths To breathe, chest wall must expand out more Dyspnea Shortness of breath, especially on exertion Breathes are rapid & shallow If end-stage: Chronic fatigue causes deconditioning Muscle weakness & wasting Barrel chest If end-stage: diaphragm will be “flat”. Continued Patient tries to expire against higher mouth air pressure, forcing airways to open wider Pursed-lip breathing Patient breathes with accessory muscles as well as diaphragm to try to improve airflow inspiratory effort further contracts diaphragmà pull the lower chest wall inwards Hoover’s sign (paradoxical shrinking of lower chest during inspiration) Tripod sitting position (activates pectoral muscles) Neck (SCM, scalene) muscles contracted Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 7, 2013 on www.thecalgaryguide.com COPD: ! 45 (on ABGs) Ventilation- perfusion mismatch High A-a gradient (calculated from ABGs) Low, flat diaphragm, >10 posterior ribs (on frontal CXR) High TLC and VC (on spirometry) • • PaO2: partial pressure of O2 in arterial blood PaCO2: partial pressure of CO2 in arterial blood • In the setting of fever and productive cough, especially if lung field opacifications are seen on CXR: consider sputum gram stain and culture to rule out pneumonia. Air does not block X-ray beams, will appear black on X-ray film Chronic hypercapnia makes breathing centers less sensitive to the high PaCO2 stimulus for breathing, & more reliant on the low PaO2 stimulus (“CO2 retention”) Give O2 carefully to these patients (high PaO2 may suppress patients’ hypoxic respiratory drive, ↓ their breathing, & ↑↑↑ PaCO2) ↑ retrosternal air space (on lateral CXR) Hyper-lucent (darker) lung fields, ↓ lung markings (on frontal CXR) • Arterial Blood Gasses (ABGs) • Chest X-Ray (CXR): frontal and lateral Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 7, 2013 on www.thecalgaryguide.com COPD: !"#$ 气流阻塞 肺泡通气↓ 呼气时，胸膜腔正压挤压气 道à 阻塞↑ 作者: Yan Yu 审稿人: Jason Baserman, Jennifer Au, Naushad Hirani*, Juri Janovcik* 译者:Zihong Xie (谢梓泓) 翻译审稿人: Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 慢性阻塞性肺疾病 (COPD) 肺组织损伤 没有弹性回缩力将 气体排出肺 肺实质与血管分布减少导 致气体交换面积↓ 弥散功能↓ (肺功能检查) 更多的CO2残留 并扩散到血液中 高碳酸血症: PaCO2 > 45 (动脉血气) 血流灌注通气不良的肺泡 时无法获得足够的氧气 总呼气时长较正常长 FEV1/FEV < 0.7 (肺功能检查) 肺无法完全排空 更多空气潴留在肺部 (肺过度充气) 低氧血症: PaO2 < 70mmHg (动脉血气) 通气-灌注不匹配 肺泡-动脉氧分压差↑ (可通过动脉血气分析计算得出) 横膈低平， 下移至第10肋后端 及以下部位 (胸部正位片) TLC与VC增大 (肺功能检查) 缩写: • • FEV1: 1秒用 • VC:肺活量 PaO2: 动脉血 力呼气量 氧分压 空气不会阻挡X射线， 在X光片上呈现为黑色 慢性高碳酸血症使呼吸中枢对PaCO2 刺激呼吸的敏感性下降 & 更依赖于低PaO2的刺激 (“二氧化碳潴留”) 给患者吸氧时需注意(高PaO2 可能会抑制患者低氧时对呼吸的 刺激，使呼吸驱动↓ & PaCO2↑↑↑ ) • FVC: 用力肺 • 活量 • TLC:肺总量 慢阻肺相关检查 : PaCO2: 动脉 血二氧化碳 分压 胸骨后间隙↑ (胸部侧位片) 肺纹理↓ • 肺功能检查 • 动脉血气分析(Arterial Blood Gasses, ABGs) • 胸部正侧位片 • 当患者发热和湿咳，特别是胸片上见肺野不清晰时: 肺透亮度↑, (胸部正位片) 考虑进行痰革兰氏染色及痰培养以排除肺炎可能 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com COPD: Complications Lung inflammation Chronic Obstructive Pulmonary Disease (COPD) Airway obstruction ↓ inhaled air in alveoli and terminal bronchioles Rupture of emphasematous bullae on surface of lung Inhaled air leaks into pleural cavity and is trapped there Pneumothorax Feeling a loss of control over one’s life, and hopelessness for the future Goblet cell proliferation, ↑ mucus production Death of airway epithelium ciliated cells ↓ oxygenation of the blood passing through the lungs Chronic hypoxemia Kidneys compensate by ↑ erythropoietin (EPO) production ↑ Hemoglobin and red blood cell synthesis Polycythemia (secondary) Hypoxic alveoli cause the pulmonary arterioles perfusing them to reflexively vasoconstrict Since most alveoli in the lungs are hypoxic, hypoxic vasoconstriction occurs across entire lung Vasoconstriction ↑ blood pressure within lung vasculature Pulmonary hypertension ↑ workload of the right ventricle (to pump against higher pressures) To compensate, the right ventricle progressively hypertrophies and dilates, but over time its output ↓ Cor pulmonale (Right heart failure in isolation, not due to Left heart failure) Mucus trapped in airways, serve as nidus for infection Acute exacerbation of COPD (AECOPD) Pneumonia The chronic, systemic inflammation in COPD is a hyper-metabolic state that consumes calories Macro-nutrient deficiency Trouble with respiration lead to inactivity and deconditioning Wasting, muscle atrophy More inactivity and deconditioning perpetuates the cycle Depression Author: Yan Yu Reviewers: Jason Baserman Naushad Hirani* Juri Janovcik* * MD at time of publication Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 7, 2013 on www.thecalgaryguide.com COPD: !"# 肺部炎症 杯状细胞增殖， 气道上皮纤毛 粘液产生↑ 细胞死亡 黏液潴留呼吸道，成为感 染的病灶 慢性阻塞性肺疾病 (COPD) 气道阻塞à 吸入肺泡和终末细 肺大疱破裂 吸入的空气渗入 并潴留于胸腔 气胸 感觉生活失控，对未 来感到绝望 抑郁 作者: Yan Yu 审稿人: Jason Baserman, Naushad Hirani*, Juri Janovcik* 译者: Zihong Xie (谢梓泓) 翻译审稿人: Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 支气管的空气 ↓ 流经肺的血液进行气 缺氧的肺泡à灌注肺泡的肺小动 慢性阻塞性肺疾 病急性加重期 (AECOPD) 肺炎 体交换↓ 慢性低氧血症 肾脏合成促红细胞 生成素进行代偿↑ 血红蛋白与红 细胞合成↑ 红细胞增多症 (继发性) 脉发生反射性血管收缩 肺大部分肺泡缺氧à整个肺 都出现缺氧性血管收缩 肺血管收缩 à 肺血管压力↑ 肺动脉高压 ↑ 右心室负荷(泵血时对抗高压) 为了代偿，右心室逐渐肥大和扩张， 但随着病程进展，右心室输出量 ↓ 肺心病 (单独出现右心衰竭，非左心衰) COPD所致的慢性全身 呼吸困难导致活 性炎症会使机体处于高 动量减少和活动 代谢状态，消耗能量 耐量降低 宏量营养 素缺乏症 消瘦，肌肉萎缩 运动量下降和活动耐量 的降低造成恶性循环 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com " title="COPD: 发病机制 作者: Yan Yu 审稿人:Jason Baserman, Jennifer Au, Naushad Hirani*, Juri Janovcik* 译者: Zihong Xie (谢梓泓) 翻译审稿人:Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 /012 (如a1-抗胰蛋白酶缺乏) 阻止肺组织损伤的能力↓ +,-. (如长期吸烟、环境污染、感染) 肺内产生自由基 34*5 肺抗蛋白酶的失活 ↑氧化应激，炎性细胞因子，蛋白酶功能 支气管的持续、反复损伤 炎性细胞浸润， 杯状细胞增殖， 气道上皮纤毛 尤其中性粒细 黏液产生↑ 细胞死亡 气道弹性↓ (弹性回缩 肺实质的蛋白水解破坏↑ 维持气道开放 肺泡永久性异常 的结构支持↓ 扩张 胞 力) 肺气体潴留 气道狭窄与 肺过度 肺大泡 气道黏液潴留，成为感染 狭窄 病灶 塌陷 充气 肺气肿 (容易肺泡 破裂) 气道纤维化和 %&'()* 慢性阻塞性肺疾病(COPD) 临床表现 并发症 (参阅相关幻灯片) (参阅相关幻灯片) 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com COPD: Clinical Findings Lung tissue Chronic Obstructive Pulmonary Disease (COPD) damage ↓ elastic recoil to push air out of lungs on expiration Lungs don’t fully empty, air is trapped in alveoli (lung hyperinflation) ↑ lung volume means diaphragm is tonically contracted (flatter) If occurring around airways Airflow obstruction ↑ mucus production ↓ number of epithelial ciliated cells to clear away the mucus (the cells have been killed by airway inflammation) Chronic cough with sputum Author: Yan Yu Reviewers: Jason Baserman Jennifer Au Naushad Hirani* Juri Janovcik* * MD at time of publication During expiration, positive pleural pressure squeezes on airwaysà↑ obstruction ↓ ventilation of alveoli ↓ oxygenation of blood (hypoxemia) ↓ perfusion of body tissues (i.e. brain, muscle) Fatigue; ↓ exercise tolerance Total expiration time takes longer than normal Prolonged expiration More effort needed to ventilate larger lungs Respiratory muscles must work harder to breathe Turbulent airflow in narrower airways is heard on auscultation Expiratory Wheeze Diaphragm can’t flatten much further to generate deep breaths To breathe, chest wall must expand out more Dyspnea Shortness of breath, especially on exertion Breathes are rapid & shallow If end-stage: Chronic fatigue causes deconditioning Muscle weakness & wasting Barrel chest If end-stage: diaphragm will be “flat”. Continued Patient tries to expire against higher mouth air pressure, forcing airways to open wider Pursed-lip breathing Patient breathes with accessory muscles as well as diaphragm to try to improve airflow inspiratory effort further contracts diaphragmà pull the lower chest wall inwards Hoover’s sign (paradoxical shrinking of lower chest during inspiration) Tripod sitting position (activates pectoral muscles) Neck (SCM, scalene) muscles contracted Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 7, 2013 on www.thecalgaryguide.com COPD: !"#$ 慢性阻塞性肺疾病 (COPD) 如果出现在气道周围 气流阻塞 肺不能完全排空 气体，气体潴留 于肺泡(肺过度 充气) 总呼气时长大于 正常时长 呼气相延长 肺组织损伤 呼气时，将空气排出肺外 的弹性回缩力↓ 肺不能完全排空气体， 气体潴留于肺泡内 (肺过度充气) 肺容积↑，膈肌紧张 性收缩(膈肌平坦) 呼气时，胸膜腔正压挤压气道 à 气道阻塞↑ 肺泡通气↓ 血液氧合↓ (低 氧血症) 身体组织灌注 量↓ (比如脑、 肌肉) 疲劳; 运动耐量↓ 黏液生成↑ 清除黏液的上皮纤 毛细胞数量↓ (受 气道炎症损伤) 慢性咳嗽伴咳 痰 作者: Yan Yu 审稿人: Jason Baserman, Jennifer Au, Naushad Hirani*, Juri Janovcik* 译者: Zihong Xie (谢梓泓) 翻译审稿人: Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 容积较大 的肺需要 更加努力 才能通气 呼吸肌必须 更用力才能 呼吸 听诊闻及狭窄气 道中的湍流气流 呼气喘鸣音 呼吸困难 气促，尤其是劳累 膈肌无法进一步收缩以 产生深呼吸 呼吸浅快 为了呼吸， 胸壁必须延 展得更大 桶状胸 晚期病人: 患者试图在较高的口 慢性疲劳导致 患者动用辅助呼吸肌和膈肌呼吸， 腔内气压下进行呼气， 活动耐量下降 从而使气道更开放 以改善气流 晚期病人:膈肌 “平坦” ，持续吸气进一步压 缩膈肌à 向内拉季肋部胸壁 胡佛征 (吸气时，胸廓下侧季肋部内收) 缩唇呼吸 肌肉无力 & 消瘦 端坐呼吸 (调动胸肌) 颈部肌肉收 缩(胸锁乳 突肌、斜角 肌) 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com COPD: Findings on Investigations Chronic Obstructive Pulmonary Disease (COPD) Author: Yan Yu Reviewers: Jason Baserman Jennifer Au Naushad Hirani* Juri Janovcik* * MD at time of publication Airflow obstruction Lung tissue damage ↓ ventilation of alveoli Blood perfusing ill- ventilated alveoli does not receive normal amounts of oxygen During expiration, positive pleural pressure squeezes on airwaysà↑ obstruction) No elastic recoil to push air out of lungs Loss of lung parenchyma and vasculature ↓ surface area for gas exchange ↓ diffusion capacity (on spirometry) Hypoxemia: PaO2 < 70mmHg (on ABGs) Abbreviations: • FEV1: Forced expiratory volume in 1 second • FVC: Forced vital capacity • TLC: Total lung capacity • VC: Vital Capacity Investigations for COPD : • Spirometry (Pulmonary function test) Total expiration time takes longer than normal FEV1/FEV < 0.7 (on spirometry) Lungs don’t fully empty More air trapped within lungs (hyperinflation) More CO2 remains and diffuses into the blood Hypercapnia: PaCO2 > 45 (on ABGs) Ventilation- perfusion mismatch High A-a gradient (calculated from ABGs) Low, flat diaphragm, >10 posterior ribs (on frontal CXR) High TLC and VC (on spirometry) • • PaO2: partial pressure of O2 in arterial blood PaCO2: partial pressure of CO2 in arterial blood • In the setting of fever and productive cough, especially if lung field opacifications are seen on CXR: consider sputum gram stain and culture to rule out pneumonia. Air does not block X-ray beams, will appear black on X-ray film Chronic hypercapnia makes breathing centers less sensitive to the high PaCO2 stimulus for breathing, & more reliant on the low PaO2 stimulus (“CO2 retention”) Give O2 carefully to these patients (high PaO2 may suppress patients’ hypoxic respiratory drive, ↓ their breathing, & ↑↑↑ PaCO2) ↑ retrosternal air space (on lateral CXR) Hyper-lucent (darker) lung fields, ↓ lung markings (on frontal CXR) • Arterial Blood Gasses (ABGs) • Chest X-Ray (CXR): frontal and lateral Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 7, 2013 on www.thecalgaryguide.com COPD: !"#$ 气流阻塞 肺泡通气↓ 呼气时，胸膜腔正压挤压气 道à 阻塞↑ 作者: Yan Yu 审稿人: Jason Baserman, Jennifer Au, Naushad Hirani*, Juri Janovcik* 译者:Zihong Xie (谢梓泓) 翻译审稿人: Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 慢性阻塞性肺疾病 (COPD) 肺组织损伤 没有弹性回缩力将 气体排出肺 肺实质与血管分布减少导 致气体交换面积↓ 弥散功能↓ (肺功能检查) 更多的CO2残留 并扩散到血液中 高碳酸血症: PaCO2 > 45 (动脉血气) 血流灌注通气不良的肺泡 时无法获得足够的氧气 总呼气时长较正常长 FEV1/FEV < 0.7 (肺功能检查) 肺无法完全排空 更多空气潴留在肺部 (肺过度充气) 低氧血症: PaO2 < 70mmHg (动脉血气) 通气-灌注不匹配 肺泡-动脉氧分压差↑ (可通过动脉血气分析计算得出) 横膈低平， 下移至第10肋后端 及以下部位 (胸部正位片) TLC与VC增大 (肺功能检查) 缩写: • • FEV1: 1秒用 • VC:肺活量 PaO2: 动脉血 力呼气量 氧分压 空气不会阻挡X射线， 在X光片上呈现为黑色 慢性高碳酸血症使呼吸中枢对PaCO2 刺激呼吸的敏感性下降 & 更依赖于低PaO2的刺激 (“二氧化碳潴留”) 给患者吸氧时需注意(高PaO2 可能会抑制患者低氧时对呼吸的 刺激，使呼吸驱动↓ & PaCO2↑↑↑ ) • FVC: 用力肺 • 活量 • TLC:肺总量 慢阻肺相关检查 : PaCO2: 动脉 血二氧化碳 分压 胸骨后间隙↑ (胸部侧位片) 肺纹理↓ • 肺功能检查 • 动脉血气分析(Arterial Blood Gasses, ABGs) • 胸部正侧位片 • 当患者发热和湿咳，特别是胸片上见肺野不清晰时: 肺透亮度↑, (胸部正位片) 考虑进行痰革兰氏染色及痰培养以排除肺炎可能 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com COPD: Complications Lung inflammation Chronic Obstructive Pulmonary Disease (COPD) Airway obstruction ↓ inhaled air in alveoli and terminal bronchioles Rupture of emphasematous bullae on surface of lung Inhaled air leaks into pleural cavity and is trapped there Pneumothorax Feeling a loss of control over one’s life, and hopelessness for the future Goblet cell proliferation, ↑ mucus production Death of airway epithelium ciliated cells ↓ oxygenation of the blood passing through the lungs Chronic hypoxemia Kidneys compensate by ↑ erythropoietin (EPO) production ↑ Hemoglobin and red blood cell synthesis Polycythemia (secondary) Hypoxic alveoli cause the pulmonary arterioles perfusing them to reflexively vasoconstrict Since most alveoli in the lungs are hypoxic, hypoxic vasoconstriction occurs across entire lung Vasoconstriction ↑ blood pressure within lung vasculature Pulmonary hypertension ↑ workload of the right ventricle (to pump against higher pressures) To compensate, the right ventricle progressively hypertrophies and dilates, but over time its output ↓ Cor pulmonale (Right heart failure in isolation, not due to Left heart failure) Mucus trapped in airways, serve as nidus for infection Acute exacerbation of COPD (AECOPD) Pneumonia The chronic, systemic inflammation in COPD is a hyper-metabolic state that consumes calories Macro-nutrient deficiency Trouble with respiration lead to inactivity and deconditioning Wasting, muscle atrophy More inactivity and deconditioning perpetuates the cycle Depression Author: Yan Yu Reviewers: Jason Baserman Naushad Hirani* Juri Janovcik* * MD at time of publication Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 7, 2013 on www.thecalgaryguide.com COPD: !"# 肺部炎症 杯状细胞增殖， 气道上皮纤毛 粘液产生↑ 细胞死亡 黏液潴留呼吸道，成为感 染的病灶 慢性阻塞性肺疾病 (COPD) 气道阻塞à 吸入肺泡和终末细 肺大疱破裂 吸入的空气渗入 并潴留于胸腔 气胸 感觉生活失控，对未 来感到绝望 抑郁 作者: Yan Yu 审稿人: Jason Baserman, Naushad Hirani*, Juri Janovcik* 译者: Zihong Xie (谢梓泓) 翻译审稿人: Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 支气管的空气 ↓ 流经肺的血液进行气 缺氧的肺泡à灌注肺泡的肺小动 慢性阻塞性肺疾 病急性加重期 (AECOPD) 肺炎 体交换↓ 慢性低氧血症 肾脏合成促红细胞 生成素进行代偿↑ 血红蛋白与红 细胞合成↑ 红细胞增多症 (继发性) 脉发生反射性血管收缩 肺大部分肺泡缺氧à整个肺 都出现缺氧性血管收缩 肺血管收缩 à 肺血管压力↑ 肺动脉高压 ↑ 右心室负荷(泵血时对抗高压) 为了代偿，右心室逐渐肥大和扩张， 但随着病程进展，右心室输出量 ↓ 肺心病 (单独出现右心衰竭，非左心衰) COPD所致的慢性全身 呼吸困难导致活 性炎症会使机体处于高 动量减少和活动 代谢状态，消耗能量 耐量降低 宏量营养 素缺乏症 消瘦，肌肉萎缩 运动量下降和活动耐量 的降低造成恶性循环 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com " />

COPD-临床表现

COPD: 临床表现 作者: Yan Yu 审稿人:Jason Baserman, Jennifer Au, Naushad Hirani*, Juri Janovcik* 译者: Zihong Xie (谢梓泓) 翻译审稿人:Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 /012 (如a1-抗胰蛋白酶缺乏) 阻止肺组织损伤的能力↓ +,-. (如长期吸烟、环境污染、感染) 肺内产生自由基 34*5 肺抗蛋白酶的失活 ↑氧化应激，炎性细胞因子，蛋白酶功能 支气管的持续、反复损伤 炎性细胞浸润， 杯状细胞增殖， 气道上皮纤毛 尤其中性粒细 黏液产生↑ 细胞死亡 气道弹性↓ (弹性回缩 肺实质的蛋白水解破坏↑ 维持气道开放 肺泡永久性异常 的结构支持↓ 扩张 胞 力) 肺气体潴留 气道狭窄与 肺过度 肺大泡 气道黏液潴留，成为感染 狭窄 病灶 塌陷 充气 肺气肿 (容易肺泡 破裂) 气道纤维化和 %&'()* 慢性阻塞性肺疾病(COPD) 临床表现 并发症 (参阅相关幻灯片) (参阅相关幻灯片) 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com COPD: Clinical Findings Lung tissue Chronic Obstructive Pulmonary Disease (COPD) damage ↓ elastic recoil to push air out of lungs on expiration Lungs don’t fully empty, air is trapped in alveoli (lung hyperinflation) ↑ lung volume means diaphragm is tonically contracted (flatter) If occurring around airways Airflow obstruction ↑ mucus production ↓ number of epithelial ciliated cells to clear away the mucus (the cells have been killed by airway inflammation) Chronic cough with sputum Author: Yan Yu Reviewers: Jason Baserman Jennifer Au Naushad Hirani* Juri Janovcik* * MD at time of publication During expiration, positive pleural pressure squeezes on airwaysà↑ obstruction ↓ ventilation of alveoli ↓ oxygenation of blood (hypoxemia) ↓ perfusion of body tissues (i.e. brain, muscle) Fatigue; ↓ exercise tolerance Total expiration time takes longer than normal Prolonged expiration More effort needed to ventilate larger lungs Respiratory muscles must work harder to breathe Turbulent airflow in narrower airways is heard on auscultation Expiratory Wheeze Diaphragm can’t flatten much further to generate deep breaths To breathe, chest wall must expand out more Dyspnea Shortness of breath, especially on exertion Breathes are rapid & shallow If end-stage: Chronic fatigue causes deconditioning Muscle weakness & wasting Barrel chest If end-stage: diaphragm will be “flat”. Continued Patient tries to expire against higher mouth air pressure, forcing airways to open wider Pursed-lip breathing Patient breathes with accessory muscles as well as diaphragm to try to improve airflow inspiratory effort further contracts diaphragmà pull the lower chest wall inwards Hoover’s sign (paradoxical shrinking of lower chest during inspiration) Tripod sitting position (activates pectoral muscles) Neck (SCM, scalene) muscles contracted Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 7, 2013 on www.thecalgaryguide.com COPD: ! 45 (on ABGs) Ventilation- perfusion mismatch High A-a gradient (calculated from ABGs) Low, flat diaphragm, >10 posterior ribs (on frontal CXR) High TLC and VC (on spirometry) • • PaO2: partial pressure of O2 in arterial blood PaCO2: partial pressure of CO2 in arterial blood • In the setting of fever and productive cough, especially if lung field opacifications are seen on CXR: consider sputum gram stain and culture to rule out pneumonia. Air does not block X-ray beams, will appear black on X-ray film Chronic hypercapnia makes breathing centers less sensitive to the high PaCO2 stimulus for breathing, & more reliant on the low PaO2 stimulus (“CO2 retention”) Give O2 carefully to these patients (high PaO2 may suppress patients’ hypoxic respiratory drive, ↓ their breathing, & ↑↑↑ PaCO2) ↑ retrosternal air space (on lateral CXR) Hyper-lucent (darker) lung fields, ↓ lung markings (on frontal CXR) • Arterial Blood Gasses (ABGs) • Chest X-Ray (CXR): frontal and lateral Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 7, 2013 on www.thecalgaryguide.com COPD: !"#$ 气流阻塞 肺泡通气↓ 呼气时，胸膜腔正压挤压气 道à 阻塞↑ 作者: Yan Yu 审稿人: Jason Baserman, Jennifer Au, Naushad Hirani*, Juri Janovcik* 译者:Zihong Xie (谢梓泓) 翻译审稿人: Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 慢性阻塞性肺疾病 (COPD) 肺组织损伤 没有弹性回缩力将 气体排出肺 肺实质与血管分布减少导 致气体交换面积↓ 弥散功能↓ (肺功能检查) 更多的CO2残留 并扩散到血液中 高碳酸血症: PaCO2 > 45 (动脉血气) 血流灌注通气不良的肺泡 时无法获得足够的氧气 总呼气时长较正常长 FEV1/FEV < 0.7 (肺功能检查) 肺无法完全排空 更多空气潴留在肺部 (肺过度充气) 低氧血症: PaO2 < 70mmHg (动脉血气) 通气-灌注不匹配 肺泡-动脉氧分压差↑ (可通过动脉血气分析计算得出) 横膈低平， 下移至第10肋后端 及以下部位 (胸部正位片) TLC与VC增大 (肺功能检查) 缩写: • • FEV1: 1秒用 • VC:肺活量 PaO2: 动脉血 力呼气量 氧分压 空气不会阻挡X射线， 在X光片上呈现为黑色 慢性高碳酸血症使呼吸中枢对PaCO2 刺激呼吸的敏感性下降 & 更依赖于低PaO2的刺激 (“二氧化碳潴留”) 给患者吸氧时需注意(高PaO2 可能会抑制患者低氧时对呼吸的 刺激，使呼吸驱动↓ & PaCO2↑↑↑ ) • FVC: 用力肺 • 活量 • TLC:肺总量 慢阻肺相关检查 : PaCO2: 动脉 血二氧化碳 分压 胸骨后间隙↑ (胸部侧位片) 肺纹理↓ • 肺功能检查 • 动脉血气分析(Arterial Blood Gasses, ABGs) • 胸部正侧位片 • 当患者发热和湿咳，特别是胸片上见肺野不清晰时: 肺透亮度↑, (胸部正位片) 考虑进行痰革兰氏染色及痰培养以排除肺炎可能 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com COPD: Complications Lung inflammation Chronic Obstructive Pulmonary Disease (COPD) Airway obstruction ↓ inhaled air in alveoli and terminal bronchioles Rupture of emphasematous bullae on surface of lung Inhaled air leaks into pleural cavity and is trapped there Pneumothorax Feeling a loss of control over one’s life, and hopelessness for the future Goblet cell proliferation, ↑ mucus production Death of airway epithelium ciliated cells ↓ oxygenation of the blood passing through the lungs Chronic hypoxemia Kidneys compensate by ↑ erythropoietin (EPO) production ↑ Hemoglobin and red blood cell synthesis Polycythemia (secondary) Hypoxic alveoli cause the pulmonary arterioles perfusing them to reflexively vasoconstrict Since most alveoli in the lungs are hypoxic, hypoxic vasoconstriction occurs across entire lung Vasoconstriction ↑ blood pressure within lung vasculature Pulmonary hypertension ↑ workload of the right ventricle (to pump against higher pressures) To compensate, the right ventricle progressively hypertrophies and dilates, but over time its output ↓ Cor pulmonale (Right heart failure in isolation, not due to Left heart failure) Mucus trapped in airways, serve as nidus for infection Acute exacerbation of COPD (AECOPD) Pneumonia The chronic, systemic inflammation in COPD is a hyper-metabolic state that consumes calories Macro-nutrient deficiency Trouble with respiration lead to inactivity and deconditioning Wasting, muscle atrophy More inactivity and deconditioning perpetuates the cycle Depression Author: Yan Yu Reviewers: Jason Baserman Naushad Hirani* Juri Janovcik* * MD at time of publication Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 7, 2013 on www.thecalgaryguide.com COPD: !"# 肺部炎症 杯状细胞增殖， 气道上皮纤毛 粘液产生↑ 细胞死亡 黏液潴留呼吸道，成为感 染的病灶 慢性阻塞性肺疾病 (COPD) 气道阻塞à 吸入肺泡和终末细 肺大疱破裂 吸入的空气渗入 并潴留于胸腔 气胸 感觉生活失控，对未 来感到绝望 抑郁 作者: Yan Yu 审稿人: Jason Baserman, Naushad Hirani*, Juri Janovcik* 译者: Zihong Xie (谢梓泓) 翻译审稿人: Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 支气管的空气 ↓ 流经肺的血液进行气 缺氧的肺泡à灌注肺泡的肺小动 慢性阻塞性肺疾 病急性加重期 (AECOPD) 肺炎 体交换↓ 慢性低氧血症 肾脏合成促红细胞 生成素进行代偿↑ 血红蛋白与红 细胞合成↑ 红细胞增多症 (继发性) 脉发生反射性血管收缩 肺大部分肺泡缺氧à整个肺 都出现缺氧性血管收缩 肺血管收缩 à 肺血管压力↑ 肺动脉高压 ↑ 右心室负荷(泵血时对抗高压) 为了代偿，右心室逐渐肥大和扩张， 但随着病程进展，右心室输出量 ↓ 肺心病 (单独出现右心衰竭，非左心衰) COPD所致的慢性全身 呼吸困难导致活 性炎症会使机体处于高 动量减少和活动 代谢状态，消耗能量 耐量降低 宏量营养 素缺乏症 消瘦，肌肉萎缩 运动量下降和活动耐量 的降低造成恶性循环 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com " title="COPD: 临床表现 作者: Yan Yu 审稿人:Jason Baserman, Jennifer Au, Naushad Hirani*, Juri Janovcik* 译者: Zihong Xie (谢梓泓) 翻译审稿人:Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 /012 (如a1-抗胰蛋白酶缺乏) 阻止肺组织损伤的能力↓ +,-. (如长期吸烟、环境污染、感染) 肺内产生自由基 34*5 肺抗蛋白酶的失活 ↑氧化应激，炎性细胞因子，蛋白酶功能 支气管的持续、反复损伤 炎性细胞浸润， 杯状细胞增殖， 气道上皮纤毛 尤其中性粒细 黏液产生↑ 细胞死亡 气道弹性↓ (弹性回缩 肺实质的蛋白水解破坏↑ 维持气道开放 肺泡永久性异常 的结构支持↓ 扩张 胞 力) 肺气体潴留 气道狭窄与 肺过度 肺大泡 气道黏液潴留，成为感染 狭窄 病灶 塌陷 充气 肺气肿 (容易肺泡 破裂) 气道纤维化和 %&'()* 慢性阻塞性肺疾病(COPD) 临床表现 并发症 (参阅相关幻灯片) (参阅相关幻灯片) 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com COPD: Clinical Findings Lung tissue Chronic Obstructive Pulmonary Disease (COPD) damage ↓ elastic recoil to push air out of lungs on expiration Lungs don’t fully empty, air is trapped in alveoli (lung hyperinflation) ↑ lung volume means diaphragm is tonically contracted (flatter) If occurring around airways Airflow obstruction ↑ mucus production ↓ number of epithelial ciliated cells to clear away the mucus (the cells have been killed by airway inflammation) Chronic cough with sputum Author: Yan Yu Reviewers: Jason Baserman Jennifer Au Naushad Hirani* Juri Janovcik* * MD at time of publication During expiration, positive pleural pressure squeezes on airwaysà↑ obstruction ↓ ventilation of alveoli ↓ oxygenation of blood (hypoxemia) ↓ perfusion of body tissues (i.e. brain, muscle) Fatigue; ↓ exercise tolerance Total expiration time takes longer than normal Prolonged expiration More effort needed to ventilate larger lungs Respiratory muscles must work harder to breathe Turbulent airflow in narrower airways is heard on auscultation Expiratory Wheeze Diaphragm can’t flatten much further to generate deep breaths To breathe, chest wall must expand out more Dyspnea Shortness of breath, especially on exertion Breathes are rapid & shallow If end-stage: Chronic fatigue causes deconditioning Muscle weakness & wasting Barrel chest If end-stage: diaphragm will be “flat”. Continued Patient tries to expire against higher mouth air pressure, forcing airways to open wider Pursed-lip breathing Patient breathes with accessory muscles as well as diaphragm to try to improve airflow inspiratory effort further contracts diaphragmà pull the lower chest wall inwards Hoover’s sign (paradoxical shrinking of lower chest during inspiration) Tripod sitting position (activates pectoral muscles) Neck (SCM, scalene) muscles contracted Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 7, 2013 on www.thecalgaryguide.com COPD: !"#$ 慢性阻塞性肺疾病 (COPD) 如果出现在气道周围 气流阻塞 肺不能完全排空 气体，气体潴留 于肺泡(肺过度 充气) 总呼气时长大于 正常时长 呼气相延长 肺组织损伤 呼气时，将空气排出肺外 的弹性回缩力↓ 肺不能完全排空气体， 气体潴留于肺泡内 (肺过度充气) 肺容积↑，膈肌紧张 性收缩(膈肌平坦) 呼气时，胸膜腔正压挤压气道 à 气道阻塞↑ 肺泡通气↓ 血液氧合↓ (低 氧血症) 身体组织灌注 量↓ (比如脑、 肌肉) 疲劳; 运动耐量↓ 黏液生成↑ 清除黏液的上皮纤 毛细胞数量↓ (受 气道炎症损伤) 慢性咳嗽伴咳 痰 作者: Yan Yu 审稿人: Jason Baserman, Jennifer Au, Naushad Hirani*, Juri Janovcik* 译者: Zihong Xie (谢梓泓) 翻译审稿人: Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 容积较大 的肺需要 更加努力 才能通气 呼吸肌必须 更用力才能 呼吸 听诊闻及狭窄气 道中的湍流气流 呼气喘鸣音 呼吸困难 气促，尤其是劳累 膈肌无法进一步收缩以 产生深呼吸 呼吸浅快 为了呼吸， 胸壁必须延 展得更大 桶状胸 晚期病人: 患者试图在较高的口 慢性疲劳导致 患者动用辅助呼吸肌和膈肌呼吸， 腔内气压下进行呼气， 活动耐量下降 从而使气道更开放 以改善气流 晚期病人:膈肌 “平坦” ，持续吸气进一步压 缩膈肌à 向内拉季肋部胸壁 胡佛征 (吸气时，胸廓下侧季肋部内收) 缩唇呼吸 肌肉无力 & 消瘦 端坐呼吸 (调动胸肌) 颈部肌肉收 缩(胸锁乳 突肌、斜角 肌) 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com COPD: Findings on Investigations Chronic Obstructive Pulmonary Disease (COPD) Author: Yan Yu Reviewers: Jason Baserman Jennifer Au Naushad Hirani* Juri Janovcik* * MD at time of publication Airflow obstruction Lung tissue damage ↓ ventilation of alveoli Blood perfusing ill- ventilated alveoli does not receive normal amounts of oxygen During expiration, positive pleural pressure squeezes on airwaysà↑ obstruction) No elastic recoil to push air out of lungs Loss of lung parenchyma and vasculature ↓ surface area for gas exchange ↓ diffusion capacity (on spirometry) Hypoxemia: PaO2 < 70mmHg (on ABGs) Abbreviations: • FEV1: Forced expiratory volume in 1 second • FVC: Forced vital capacity • TLC: Total lung capacity • VC: Vital Capacity Investigations for COPD : • Spirometry (Pulmonary function test) Total expiration time takes longer than normal FEV1/FEV < 0.7 (on spirometry) Lungs don’t fully empty More air trapped within lungs (hyperinflation) More CO2 remains and diffuses into the blood Hypercapnia: PaCO2 > 45 (on ABGs) Ventilation- perfusion mismatch High A-a gradient (calculated from ABGs) Low, flat diaphragm, >10 posterior ribs (on frontal CXR) High TLC and VC (on spirometry) • • PaO2: partial pressure of O2 in arterial blood PaCO2: partial pressure of CO2 in arterial blood • In the setting of fever and productive cough, especially if lung field opacifications are seen on CXR: consider sputum gram stain and culture to rule out pneumonia. Air does not block X-ray beams, will appear black on X-ray film Chronic hypercapnia makes breathing centers less sensitive to the high PaCO2 stimulus for breathing, & more reliant on the low PaO2 stimulus (“CO2 retention”) Give O2 carefully to these patients (high PaO2 may suppress patients’ hypoxic respiratory drive, ↓ their breathing, & ↑↑↑ PaCO2) ↑ retrosternal air space (on lateral CXR) Hyper-lucent (darker) lung fields, ↓ lung markings (on frontal CXR) • Arterial Blood Gasses (ABGs) • Chest X-Ray (CXR): frontal and lateral Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 7, 2013 on www.thecalgaryguide.com COPD: !"#$ 气流阻塞 肺泡通气↓ 呼气时，胸膜腔正压挤压气 道à 阻塞↑ 作者: Yan Yu 审稿人: Jason Baserman, Jennifer Au, Naushad Hirani*, Juri Janovcik* 译者:Zihong Xie (谢梓泓) 翻译审稿人: Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 慢性阻塞性肺疾病 (COPD) 肺组织损伤 没有弹性回缩力将 气体排出肺 肺实质与血管分布减少导 致气体交换面积↓ 弥散功能↓ (肺功能检查) 更多的CO2残留 并扩散到血液中 高碳酸血症: PaCO2 > 45 (动脉血气) 血流灌注通气不良的肺泡 时无法获得足够的氧气 总呼气时长较正常长 FEV1/FEV < 0.7 (肺功能检查) 肺无法完全排空 更多空气潴留在肺部 (肺过度充气) 低氧血症: PaO2 < 70mmHg (动脉血气) 通气-灌注不匹配 肺泡-动脉氧分压差↑ (可通过动脉血气分析计算得出) 横膈低平， 下移至第10肋后端 及以下部位 (胸部正位片) TLC与VC增大 (肺功能检查) 缩写: • • FEV1: 1秒用 • VC:肺活量 PaO2: 动脉血 力呼气量 氧分压 空气不会阻挡X射线， 在X光片上呈现为黑色 慢性高碳酸血症使呼吸中枢对PaCO2 刺激呼吸的敏感性下降 & 更依赖于低PaO2的刺激 (“二氧化碳潴留”) 给患者吸氧时需注意(高PaO2 可能会抑制患者低氧时对呼吸的 刺激，使呼吸驱动↓ & PaCO2↑↑↑ ) • FVC: 用力肺 • 活量 • TLC:肺总量 慢阻肺相关检查 : PaCO2: 动脉 血二氧化碳 分压 胸骨后间隙↑ (胸部侧位片) 肺纹理↓ • 肺功能检查 • 动脉血气分析(Arterial Blood Gasses, ABGs) • 胸部正侧位片 • 当患者发热和湿咳，特别是胸片上见肺野不清晰时: 肺透亮度↑, (胸部正位片) 考虑进行痰革兰氏染色及痰培养以排除肺炎可能 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com COPD: Complications Lung inflammation Chronic Obstructive Pulmonary Disease (COPD) Airway obstruction ↓ inhaled air in alveoli and terminal bronchioles Rupture of emphasematous bullae on surface of lung Inhaled air leaks into pleural cavity and is trapped there Pneumothorax Feeling a loss of control over one’s life, and hopelessness for the future Goblet cell proliferation, ↑ mucus production Death of airway epithelium ciliated cells ↓ oxygenation of the blood passing through the lungs Chronic hypoxemia Kidneys compensate by ↑ erythropoietin (EPO) production ↑ Hemoglobin and red blood cell synthesis Polycythemia (secondary) Hypoxic alveoli cause the pulmonary arterioles perfusing them to reflexively vasoconstrict Since most alveoli in the lungs are hypoxic, hypoxic vasoconstriction occurs across entire lung Vasoconstriction ↑ blood pressure within lung vasculature Pulmonary hypertension ↑ workload of the right ventricle (to pump against higher pressures) To compensate, the right ventricle progressively hypertrophies and dilates, but over time its output ↓ Cor pulmonale (Right heart failure in isolation, not due to Left heart failure) Mucus trapped in airways, serve as nidus for infection Acute exacerbation of COPD (AECOPD) Pneumonia The chronic, systemic inflammation in COPD is a hyper-metabolic state that consumes calories Macro-nutrient deficiency Trouble with respiration lead to inactivity and deconditioning Wasting, muscle atrophy More inactivity and deconditioning perpetuates the cycle Depression Author: Yan Yu Reviewers: Jason Baserman Naushad Hirani* Juri Janovcik* * MD at time of publication Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 7, 2013 on www.thecalgaryguide.com COPD: !"# 肺部炎症 杯状细胞增殖， 气道上皮纤毛 粘液产生↑ 细胞死亡 黏液潴留呼吸道，成为感 染的病灶 慢性阻塞性肺疾病 (COPD) 气道阻塞à 吸入肺泡和终末细 肺大疱破裂 吸入的空气渗入 并潴留于胸腔 气胸 感觉生活失控，对未 来感到绝望 抑郁 作者: Yan Yu 审稿人: Jason Baserman, Naushad Hirani*, Juri Janovcik* 译者: Zihong Xie (谢梓泓) 翻译审稿人: Yonglin Mai (麦泳琳), Zesheng Ye (叶泽生) * 发表时担任临床医生 支气管的空气 ↓ 流经肺的血液进行气 缺氧的肺泡à灌注肺泡的肺小动 慢性阻塞性肺疾 病急性加重期 (AECOPD) 肺炎 体交换↓ 慢性低氧血症 肾脏合成促红细胞 生成素进行代偿↑ 血红蛋白与红 细胞合成↑ 红细胞增多症 (继发性) 脉发生反射性血管收缩 肺大部分肺泡缺氧à整个肺 都出现缺氧性血管收缩 肺血管收缩 à 肺血管压力↑ 肺动脉高压 ↑ 右心室负荷(泵血时对抗高压) 为了代偿，右心室逐渐肥大和扩张， 但随着病程进展，右心室输出量 ↓ 肺心病 (单独出现右心衰竭，非左心衰) COPD所致的慢性全身 呼吸困难导致活 性炎症会使机体处于高 动量减少和活动 代谢状态，消耗能量 耐量降低 宏量营养 素缺乏症 消瘦，肌肉萎缩 运动量下降和活动耐量 的降低造成恶性循环 图注: 病理生理 机制 体征/临床表现/实验室检查 并发症 2013年1月7日发布于 www.thecalgaryguide.com " />

Chronic Cough Pathogenesis_2021

Chronic Cough: Pathogenesis ACE Inhibitors Protussive mediator accumulation (bradykinin, substance P) Infection IP; likely chronic ↑ cough receptors commonly pertussis- related or post-viral Asthma ↑ EDN ↑ MBP levels in RT Neoplasm Bronchiectasis COPD GERD Allergic Rhinitis ↑ sputum production and accumulation Damage from chronic inflammation causes poor mucus clearance Inhalants trigger ↑ cytokines ↑ mucus Aspiration of refluxed microdroplets Irritation by post- nasal drip ↑ inflammatory mediators in RT Mechanical obstructions (i.e. mediastinal masses, neoplasms) Foreign body Presence irritation of irritants Stimulation of sensory nerve receptors expressed on nerve endings penetrating the epithelia of the upper RT Abbreviations: • RT: respiratory tract • IP: indefinite pathophysiology • GERD: Gastro-esophageal reflux disease • EDN: Eosinophil-derived neurotoxin • MBP: Major basic protein • COPD: Chronic Obstructive Pulmonary Disease Complications: Syncope, insomnia, hemoptysis, rib fractures Slowly adapting receptors Respond to mechanical forces during breathing Stimulation of the vagus nerve Activation of nucleus tractus solitarius in central respiratory generator (brainstem) Generation of efferent cough signal Chronic cough: Cough of over 8 weeks duration with no dyspnea or fever C-fibre receptors Respond to chemical stimuli (bradykinin, capsaicin, acid/alkaline solutions, mannitol, hypertonic saline, and other inhaled irritants) Authors: Arsalan Ahmad Lance Bartel Reviewers: Midas (Kening) Kang Usama Malik Ciara Hanly Yonglin Mai (麦泳琳) Yan Yu*, Eric Leung* * MD at time of publication Rapidly adapting receptors Responds to mechanical stimuli, such as physical obstruction of the airways Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Feb 06, 2018, updated Dec 4, 2021 on www.thecalgaryguide.com

complications-of-chronic-kidney-disease-ckd

Complications of Chronic Kidney Disease Chronic Kidney Disease (CKD) Authors: Samin Dolatabadi, Brooke Fallis Reviewers: Jessica Krahn, Meena Assad, Yan Yu* Juliya Hemmett* * MD at time of publication Abnormalities of kidney structure or function that is present for 3 or more months Kidney tubules atrophy & kidney interstitial tissue undergo fibrosis Kidney damage ↓ erythropoietin production (normally a kidney function) ↓stimulation of bone marrow → ↓ red blood cell production Build up of toxic substances (e.g. urea, guanidine, and indoxyl sulfate) ↓ Conversion of calcidiol to calcitriol in by kidney ↓ Calcitriol levels in blood ↓ Ca+2 absorption from small intestine Hypocalcemia ↓ Glomerular Filtration Rate ↑ Vascular calcification and endothelial dysfunction (e.g. changes in permeability, clotting response to inflammation, amongst other mechanisms) Atherosclerotic disease (see “Complications of Atherosclerosis” slide) ↓ Lipoprotein lipase, apoA-1, and Lecithin-cholesterol acyltransferase activity acting on serum lipoproteins (complex mechanisms) ↓ Lipoprotein clearance from blood Dyslipidemia (↑ LDL, ↑ triglycerides, ↓ HDL) Toxic damage ↓ red blood cell survival Anemia Uremic Syndrome ↓ Renal excretion of phosphate ↑ phosphate remaining in bloodstream Hyperphosphatemia ↑ serum phosphate binds with ionized calcium ↓ Renal excretion of K+ ↑ K+ remaining in bloodstream Hyperkalemia Edema ↓ Renal excretion of ammonium Reduced filtration capability ↑ organic anions remaining in blood→ ↑ anion gap ↓ Renal excretion of salt and water ↑ in extracellular fluid → systemic volume overload ↓ calcium in blood ↓ inhibition of Parathyroid Hormone (PTH) release ↑ PTH in blood Secondary hyperparathyroidism Metabolic Acidosis Hypertension Pitting Chronic kidney disease – mineral and bone disorder (CKD-MBD) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Jan 4, 2022 on www.thecalgaryguide.com

NSAIDs and the Kidney Nephrotoxicity

NSAIDs and the Kidney: NSAID induced Nephrotoxicity Non-steroidal anti-inflammatory drugs (NSAID) Authors: Kyle Moxham Mehul Gupta Reviewers: Emily Wildman Yan Yu* Adam Bass* * MD at time of publication Inhibition of Cyclooxygenase COX-1 (expressed in kidney) and COX-2 (expressed in kidney and sites of inflammation) NSAID induced nephrotoxicity: associated with chronic NSAID usage independent of dosage COX inhibition ↑ conversion of arachidonic acid (AA) to leukotrienes, causing systemic T-cell dysfunction (unknown mechanism) Type IV systemic hypersensitivity (delayed T helper cell mediated) reaction to drug exposure T cells release inflammatory cytokines into the bloodstream (see Calgary Guide slide on NSAIDs and the Kidney: Mechanism of Action and Side Effects) T cells infiltrate the renal interstitium, sparing the glomeruli and blood vessels Overproduction of cytokines by T cells causing inflammation, tissue damage, and cell death, of the renal intersitium Drug Induced Acute interstitial nephritis (AIN): a type of immune-mediated tubulointerstitial injury Activated T-cells infiltrate the glomerulus and cause podocyte injury (epithelial cells attached to the glomerular basement membrane) Membranous nephropathy: nephrotic syndrome involving autoimmune glomerular basement membrane thickening & complete podocyte effacement (seen on kidney biopsy) Minimal change disease: nephrotic syndrome caused by autoimmune podocyte effacement (seen on kidney biopsy) Cytokine mediated activation and proliferation of immune cells like macrophages and eosinophils Cytokines travel to hypothalamus, causing change in the body’s thermal set point Fever Podocyte effacement allows for serum proteins to across the glomerulus into the tubular lumen (see Calgary Guide slide on Nephrotic Syndrome for full mechanisms) Repeated NSAID exposure causing recurrent unrecognized AIN and damage of the kidney Chronic interstitial nephritis /analgesic nephropathy Infiltrating immune cells (predominantly neutrophils) are filtered into/enter the renal tubules, and form clumps (“casts”) within the tubulesà casts are then released into urine WBC cast on urinalysis ↑ Blood eosinophils Immune cells infiltrate the dermis and epidermis of the skin Rash Abnormal quantities of protein present in urine Protein present in the blood is improperly filtered into the filtrate at the glomerulus Protein- Creatinine Ratio >3.5mg/mg Proteinuria >3.5g/d Hypo- albuminemia ↓ plasma oncotic pressure resulting in fluid extravasation into the interstitium (see Calgary guide slide on Edema for full mechanisms) Pitting Edema Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 13, 2022 on www.thecalgaryguide.com

Langerhans Cell Histiocytosis

Langerhans Cell Histiocytosis: Pathogenesis and clinical findings Precursor cells differentiateàClonal expansion of abnormal (constitutive MAPK activation) CD1a+/CD207+ (Langerhans cell phenotype surface receptors) dendritic cells in tissue(s) Somatic BRAFV600E mutation: BRAF is a kinase in the MAPK pathway Other somatic (non- reproductive cell) mutations Idiopathic (unknown cause) Mutation(s) can occur in one of these precursor cell types* Hematopoietic stem cell (earliest cell of blood cell differentiation) in bone marrow Committed dendritic cell (type of myeloid antigen-presenting cell) precursor in bone marrow or blood Committed dendritic cell precursor in tissue Constitutive activation of the MAPK pathway (signalling pathway that regulates variety of cellular processes) in one of these precursor cell types *Note: Based on the “misguided myeloid differentiation” modelàthe earlier the mutation(s) occur in the myeloid cell differentiation pathway, the more severe the disease. Langerhans Cell Histiocytosis Accumulation of abnormal CD1a+/CD207+ dendritic cells (Langerhans Cell Histiocytosis cells or LCH cells) with an inflammatory background in one or more organs Authors: Ran (Marissa) Zhang Reviewers: Mehul Gupta Kiera Pajunen Yan Yu* Lynn Savoie* * MD at time of publication ↑ recruitment & activation of T cells, macrophages, eosinophils in tissue(s) around the body ↓ CCR7 & CXCR4 (chemokine receptors) expression on LCH cellsàinhibits migration of LCH cells to lymph nodes ↑ BCLXL (an apoptosis regulator protein) expression on LCH cellsà inhibits apoptosis of LCH cells Immune cell infiltration & ↑ pro-inflammatory chemokine/cytokine release à dysregulated local & systemic inflammation Accumulation of LCH cells in tissue(s) around the body Inflammatory lesion (an area of abnormal tissue) formation in one or more organs: In pituitary stalk Mass effectà obstruction of antidiuretic hormone (complex mechanisms) In liver Invasion & accumulation of cells foreign to liverà expands liver Chronic local inflammation Scarring of bile ducts ↓ bilirubin clearance from liveràbuildup into serum ↑ serum bilirubin Jaundice In cortical bone Cytokine production à↑ osteoclast (cells that break down bone) activity ↑ rate of bone loss Osteolytic bone lesions In bone marrow Unclear mechanism but likely due to macrophage activation ↑ phagocytosis (ingestion & destruction) of blood cells In spleen Invasion & accumulation of cells foreign to spleen Forms aggregates that expand the red pulp (functions as the blood filter in spleen) Splenomegaly In skin Unclear mechanisms Variable presentations: most commonly pinpoint erythematous (red) papules or erythematous plaques with crusting & scaling Hepatomegaly • BRAF- B-Raf proto-oncogene, serine/threonine kinase • CCR7- C-C motif chemokine receptor type 7 • CD1a- Cluster of differentiation 1A • CD207- C-type lectin domain family 4 member k • CXCR4- C-X-C chemokine receptor type 4 • LCH- Langerhans Cell Histiocytosis • MAPK- Mitogen-activated protein kinase Diabetes Insipidus Abbreviations: • BCLXL- B-cell lymphoma-extra large Anemia, thrombocytopenia &/or neutropenia Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 13, 2022 on www.thecalgaryguide.com

NSAIDs and the Kidney mechanism of action and side effects

NSAIDs and the Kidney: Mechanism of Action and Side Effects Authors: Kyle Moxham Mehul Gupta Reviewers: Emily Wildman Yan Yu* Adam Bass* *MD at time of publication Concurrent use of angiotensin- converting enzyme inhibitors (ACEi) or angiotensin II receptor blockers (ARB) AECi and ARBs act to ↓ renin- angiotensin-aldosterone system (RAAS) activation Reduced angiotensin (AT) 2 activity at its receptors on efferent arteriole of the nephron Net vasodilation of efferent arterioles ↓ in glomerular pressure ↓ blood perfusing kidney tissueà↑ hypoxemia & renal ischemia Pre-existing ↓effective arterial blood volume (EABV) from dehydration, GI loss, diuretics, CKD, CHF, cirrhosis, etc. Decreased EABV triggers endogenous renal autoregulation, resulting in norepinephrine (NE) mediated vasoconstriction of afferent arteriole of the nephron Net ↓ in renal blood flow and ↓ in glomerular pressure ↓ volume of blood filtered by the glomeruli per unit time Non-steroidal anti-inflammatory drugs (NSAIDs) Inhibition of Cyclooxygenase COX-1 (expressed in kidney) and COX-2 (expressed in kidney and sites of inflammation) ↓ Renal prostaglandin (PG) synthesis: local hormones involved in renal homeostasis NSAID induced nephrotoxicity: associated with chronic usage independent of dosage (see Calgary Guide slide on NSAIDs and the Kidney: NSAID induced nephrotoxicity) ↓ intrarenal PG reduces inhibitory effects of PG over ADH in cortical colleting duct (CCD) of the kidneyà↓ antagonism on ADH activity ↑ ADH activity causes insertion of more aquaporins (water channels) in the collecting duct of renal tubules Net ↑ in volume of water reabsorbed into the blood ↓ vasodilatory effect of PG at the afferent arteriole of the nephron ↓ Glomerular filtration rate (GFR) ↓ PG signalling results in ↓ renin secretion at juxtaglomerular apparatus Low renin levelsà↓ conversion of angiotensinogen into its AT1 form and, by extension, ACE mediated conversion of AT1 to AT2 ↓ ACE 2 signalling leads to ↓ levels of aldosterone in the serum ↓ Na+ and K+ channel insertion on apical surface and ↓ Na/K ATPase activity on basolateral surface of principal cells ↓ K+ excretion into urine, and ↓ Na+ reabsorption back into the blood, at the late DCT and collecting duct of the kidney Pre-renal Acute Kidney Injury (AKI): kidney injury due to renal hypoperfusion Prolonged and/or severe ischemia causes cell death and aggregation of tubular epithelial cells of the kidney with subsequent inability to reabsorb luminal Na+ Renal dehydration predisposes precipitation of uromodulin protein Renal tubules mold uromodulin into cylindrical structures known as “casts”. Casts that contain only uromodulin protein are known as “hyaline casts” Hyaline cast seen on urinalysis Hypoperfusion of the kidney activates the renin- angiotensin- aldosterone system (RAAS) ↑ amount of sodium (Na) reabsorbed from the filtrate (less Na excreted) Fractional excretion of Na <1% Papillary necrosis: ureteral passage of sloughed ischemic tissue causing ureteral obstruction Acute tubular necrosis: a type of kidney injury causing damage to the tubules Hypertension Post-renal AKI: a type of kidney injury due to obstruction of the urinary tract Distal distal obstruction of the urinary tract causes fluid to accumulate within the kidneysàenlarging the kidneys Renal Ultrasound shows hydronephrosis (enlarged kidneys) Damaged tubule epithelial cells slough into the tubular lumen Epithelial cell breakdown in the tubular lumen releases uromodulin & other proteins, which aggregate into “casts” (cylindrical imprints of the renal tubule). The varied protein content of these casts result in them having a coarse, granular appearance Damaged tubular epithelial cells are unable to properly reabsorb sodium ↓ amount of sodium (Na) reabsorbed from filtrate into the blood (more Na excreted) Fractional excretion of Na >2% True excess of free water relative to Na+ in the blood Excess free water ↑ venous hydrostatic pressure (see Calgary Guide slide on edema for full mechanisms) Pitting Edema Hyperkalemia Hyponatremia Coarse granular casts seen on urinalysis Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 29, 2022 on www.thecalgaryguide.com

adult-pneumonia-pathogenesis-and-clinical-findings

Adult Pneumonia: Pathogenesis and clinical findings Author: Laura Byford-Richardson Reviewers: Tara Shannon, *Yan Yu, Sadie Kutz , Natalie Morgunov, *Kerri Johannson, *Julie Carson *MD at time of publication Smoking à suppressed neutrophil function and damaged lung epithelium Chronic lung conditions e.g. COPD, asthma, lung canceràdestroys lung tissue and offers pathogen more niduses for infection Immune suppression e.g. HIV, sepsis, glucocorticoids, chemotherapyà suppression of immune response Systemic inflammatory response towards invading microbe Systemic cytokine release leads to a disruption in hypothalamic thermoregulation Exposure to a pathogen via inhalation, aspiration, contiguous Notes: or hematological mechanism Susceptible host and/or virulent pathogen Proliferation of microbe in lower airways and alveoli Local response by alveolar epithelial cells release chemokines into surrounding tissue to recruit neutrophils to the site of inflammation • Pathogens can be bacteria, viruses, fungi and parasites • Pneumonia is a lower respiratory tract infection (in contrast to upper respiratory tract infections such as bronchitis) and can be further classified by location of exposure: community, health- care, hospital acquired Inflammatory response varies depending on type of invading pathogen (i.e. S. Pneumonia causes a lobar pattern and Influenza A & B cause an interstitial pattern) LOBAR: Accumulation of neutrophils and plasma exudate from capillaries into alveoli specific to a lung area/lobe INTERSTITIAL: Accumulation of infiltrates (i.e. inflamed cellular debris) in the alveolar walls (i.e. space between the alveolar spaces and bloodstream) Fever Notes: • Other signs and symptoms of pneumonia exist such as chest pain, accessory muscle use, crackles on auscultation and fatigue • These signs and symptoms are less specific to the ones outlined on this slide Irritation and attempted clearance of airways Fluid infiltrates are inside alveoli, airway clearance leads to phlegm production Productive Cough Fluid build up does not allow X-rays to pass through à white opacity on plain film at site of fluid buildup Consolidation on CXR Alveolar sacs blocked by fluid accumulation Thickening of alveolar walls ↑ diffusion distance between alveoli & capillaries Irritated alveolar walls trigger cough reflex Since fluid infiltrates are NOT in the alveoli, attempts to empty the alveoli through coughing doesn’t lead to production of fluid Dry Cough Chills/Rigors ↓ Exchange of CO2 and O2 Hypoxemia Triggers peripheral and central chemoreceptors to ↑ respiratory drive Dyspnea Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Sept 26 2016, updated Feb 9, 2022 on www.thecalgaryguide.com

hip-osteoarthritis-pathogenesis-and-clinical-findings

Hip Osteoarthritis: Pathogenesis and clinical findings Authors: Ebrahim Alawadhi, Alyssa Federico Reviewers: Mehul Gupta, Tara Shannon, Yan Yu*, Richard Ng* * MD at time of publication Primary causes Aging ↓ Synovial fluid in the hip joint Secondary causes Gender Females > males Genetics Family history of osteoarthritis High-impact sports, activities, and occupations Repetitive stress on the hip joints Obesity ↑ Loading on hip joints Inflammatory disease (e.g. Rheumatoid arthritis ) Trauma Infection (e.g. septic arthritis) Anatomical abnormality (e.g. developmental hip dysplasia) ↑ Cartilage stiffness and degeneration ↑ Friction in the hip joint with movement Changes in normal hip architecture Abnormal load on the hip joint Radiographic changes See Osteoarthritis (OA): X-Ray Features slide Repeated attempts to repair cartilage damage and bone Bone spur (bony growth) formation in joint Joint fluid accumulation from mild inflammation of the joint Stiffness Limited joint movement Hip Osteoarthritis Multifactorial condition that manifests as degeneration of cartilage, bone, and synovium in the hip joint ↓ Cartilage between femoral head and acetabulum ↑ Bone on bone contact Mechanical symptoms (crepitus, locking, clicking, catching) Bones rubbing together activates nociceptors within the hip joint Nociceptors further aggravated by actions that ↑ bone on bone contact (e.g. prolonged loading, movements that ↓ joint space) Worsening pain in the groin region Favour the affected leg to avoid pain while walking ↓ Space for the femoral head to move ↓ Range of motion of affected hip joint Limited range of motion when walking Antalgic gait ↓ Use of muscles around the affected hip Muscular atrophy around the hip C Sign: patient identifies location of pain by cupping lateral hip with one hand, which creates a “C” shape with that hand Pain in groin region ↑ Sensitivity of surrounding nerves Radiating pain to buttocks and knee Inactivity Hip instability when walking Muscle contractures ↑ Falls Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published March 6, 2022 on www.thecalgaryguide.com

cough-physiology

Cough: Physiology Mass or particulate matter in the throat & airways ↑ pressure on mucosa Pressure on rapidly and slowly adapting mechanoreceptors Mechanoreceptor activation opens ion channels on vagus neurons Authors: Calvin Howard Reviewers: Nilani Sritharan Ciara Hanly Yonglin Mai (麦泳琳)* Yan Yu* Stephen Field* * MD at time of publication Systemic immune reaction Inflammation of alveoli Cytokine release Cytokines bind to sensory neurons Neurons ↑ receptor sensitivity and number ↑ sensation of stimuli Ionic flux across neuronal membrane Vagus neurons depolarize Thinly myelinated axons (Aδ fibers) General chemicals, heat, cold, and hydrogen ions Transient receptor potential vanilloid (TRPV)/Transient receptor potential ankyrin (TRPA) receptors activate TRPV/TRPA activation opens ion channels on vagus neurons Unmyelinated axons (C fibers) carry depolarization Vagus nerves conduct depolarization to carry depolarization SUMMARY Afferent pathways activated Cough center (medulla) Efferent pathways Respiratory muscles nucleus of the solitary tract Medullary nuclei activated, stimulates: Phrenic nerves Diaphragm contraction Spinal nerves External intercostal contraction Vagal nerves Glottis closure Spinal nerves Thoracic, abdominal, and pelvic muscle contraction Vagal nerves Glottis opens, allowing forceful expiration Intrathoracic pressure and volume decrease Volume in lungs increases Intrathoracic pressure increases Mechanical Cough Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Sept 1, 2019, updated Dec 5, 2021 on www.thecalgaryguide.com

isotretinoin-systemic-retinoid-mechanisms-and-side-effects

Isotretinoin (Systemic Retinoid): Mechanisms and Side Effects Isotretinoin Authors: Ayaa Alkhaleefa Reviewers: Mehul Gupta, Ben Campbell Stephen Williams, Lauren Lee, Yan Yu*, Laurie Parsons* * MD at time of publication ↑ Apoptotic signaling in sebocytes Inhibits androgen nuclear receptors responsible for sebum secretion ↓ Sebaceous lipogenesis ↑ Apoptotic signaling in neural crest cells during embryonic development Alterations in hindbrain, neural crest, otic anlage, and reduced pharyngeal arch in embryo Craniofacial, cardiac, thymic, and central nervous system malformations in fetus Isotretinoin isomerizes to all-trans retinoic acid (ATRA) ATRA enters cell nucleus and binds retinoic acid receptors and retinoic X receptors ATRA induces tumour necrosis factor-related apoptosis-inducing ligand ↑ Apoptotic signaling in epidermal keratinocytes ↑ Expression of FoxO1 ↑ Expression of p53 (tumour suppressor) Release of caspases 3, 6, 7, and 9 ↑ Cell cycle inhibitors p21 and p27 ↓ Pro-survival proteins (Survivin) Sebaceous gland involution Sebum suppression C. acnes unable to break down sebum into pro- inflammatory lipids ↓ Colonization with C. acnes Teratogenicity ↑ Cornification (death) of epidermal keratinocytes ↓ Corneodesmosomes (main adhesive structures of the stratum corneum) ↓ Cohesion of corneocytes (dead keratinocytes) ↓ Corneocyte buildup in pilosebaceous follicles C. acnes unable to populate and release cytokines in corneocytes Epidermis Dermis Pilosebaceous follicle ↓ Stratum corneum thickness ↑ Trans-epidermal water loss Dryness, peeling & inflammation of lips (cheilitis), skin (dermatitis) & mucosa (mucositis) ↓ Comedogenesis Sebum Hair follicle Dermal- Epidermal Junction Sebaceous gland (sebocytes) Death of sebocytes in pilosebaceous follicles Reduction of number and size of acne lesions Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published March 20, 2022 on www.thecalgaryguide.com

proximal-biceps-tendon-rupture

Proximal Biceps Tendon Rupture: Pathogenesis and clinical findings Author: Alyssa Federico Reviewers: Tara Shannon, Mehul Gupta, Yan Yu*, Gareth Ryan* * MD at time of publication Aging Decreased tendon strength from age- related changes in extracellular matrix Male gender Smoking Corticosteroid and fluoroquinolone use Shoulder Overuse Repetitive overhead sports like swimming & tennis Shoulder overuse injuries (rotator cuff tears, shoulder impingement, & tendonitis) place more stress on the proximal biceps tendon Repetitive microtrauma and inflammation of biceps tendon Compromised biceps tendon integrity from intra-tendinous collagen degeneration, disorientation, and thinning Increased involvement in physical labour and hobbies Impaired cell proliferation and healing after injury Exact mechanisms remain unclear Bicep tendon involved in shoulder stabilization, elbow flexion, and forearm supination Biceps muscle cannot contract with as much force when one head is detached Heavy lifting or fall on outstretched handà sudden tension in the proximal biceps tendon Proximal biceps tendon rupture Long head of proximal biceps tendon detaches from bony attachment on supraglenoid tubercle Audible “pop” at time of injury No tension to hold proximal bicep tendon head in place Proximal bicep tendon head retracts distally Biceps muscle fatigue and cramping Weakness in shoulder flexion, elbow flexion & supination Nerve damage (musculocutaneous nerve) during injury Local inflammatory response at site of injury Surrounding blood vessels damaged during injury Blood collection under skin surface Immediate bruising over rupture site Sudden and sharp pain at shoulder with initial injury Inflammatory response aggravates musculocutaneous nerve Swelling over rupture site + Speed test: affected elbow extended and forearm supinated. Shoulder flexed against resistanceàpain at bicipital groove + Neer test: on affected side, scapula stabilized while arm passively flexed and internally rotatedàpain at bicipital groove + Yergeson test: affected elbow flexed at 90° and forearm pronated. Forearm supinated against resistance àpain at bicipital groove “Popeye” deformity: mass in distal upper arm due to excessive retraction of biceps muscle distally, away from its origin Palpable gap between proximal biceps tendon and bicipital groove Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published April 20, 2022 on www.thecalgaryguide.com

distal-biceps-tendon-rupture

Distal Biceps Tendon Rupture: Pathogenesis and clinical findings Authors: Alyssa Federico Reviewers: Tara Shannon, Mehul Gupta, Yan Yu*, Gareth Ryan* * MD at time of publication Aging ↓ Tendon strength from age-related changes in extracellular matrix Male gender Overuse Common in throwing and racquet sports Repetitive microtrauma and inflammation of biceps tendon Corticosteroid and fluoroquinolone use Smoking Hypovascularity Area of hypovascularity between regions supplied by the brachial artery and posterior radial recurrent artery Impaired ability to heal from microtrauma Mechanical impingement Compression of distal biceps tendon by surrounding bone (radial tuberosity, proximal ulna) during forearm pronation Repetitive compressionà tendon degeneration ↑ Involvement in physical labour and hobbies Exact mechanisms remain unclear Impaired cell proliferation Biceps tendon inserts at the radial tuberosity to control forearm supination and flexion Compromised biceps tendon integrity from intra-tendinous collagen degeneration, disorientation, and thinning Sudden eccentric force to flexed elbow (forced lengthening of a contracted bicep muscle)àtension in the distal biceps tendon Biceps muscle cannot contract when distal tendon is detached from insertion site Distal biceps tendon rupture Complete detachment of distal biceps tendon at the attachment site on the radial tuberosity Audible “pop” at time of injury Weak forearm supination and flexion + Ruland biceps squeeze test: Affected elbow held in 60-80° of flexion, with forearm slightly pronated. Distal biceps muscle squeezed by practitioner à forearm does not supinate Local inflammatory response at site of injury Inflammatory response aggravates musculo- cutaneous nerve Pain over rupture site after initial injury Swelling over rupture site Nerve damage (musculocut aneous nerve) during injury Sudden and sharp pain at elbow at initial injury Surrounding blood vessels damaged during injury Blood collects under skin surface Immediate bruising over rupture site Biceps tendon retracts proximally High tension during tendon retraction Fragment of bone torn off from tendon insertion site on radial tuberosity Avulsion fracture of radial tuberosity Connective tissue attachment (aponeurosis) torn during injury Palpable gap between distal end of biceps tendon & radial tuberosity + Hook test: Elbow actively flexed to 90° and forearm supinated. Index finger of examiner cannot be placed beneath distal aspect of biceps tendon (>1 cm deep) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published April 20, 2022 on www.thecalgaryguide.com

irritable-bowel-syndrome-ibs-pathogenesis-and-clinical-findings

Irritable Bowel Syndrome (IBS): Pathogenesis and clinical findings Authors: Ben Campbell Reviewers: Mehul Gupta Kiana Hampton Yan Yu* Edwin Cheng* * MD at time of publication Note: *Several signaling pathways in the gut are believed to play a role in IBS. The serotonin pathway is represented here for illustrative purposes, and it is a common target of therapy. Pathogenesis is multifactorial, not fully understood, and may arise from any one or a combination of these factors Genetic factors are believed to influence many of these pathways Environmental factors Gut infection, ischemia, injury, chronic low-level inflammation, altered microbiome Abnormal gut chemical milieu (cytokines, lymphocytes, mast cells, hormones) One common pathway: altered quantity or activity of serotonin-releasing enterochromaffin * cells and serotonin reuptake transporters in gut Serotonin is a key stimulator of gut muscle contraction and sensory signaling Altered bowel motility Bowel motility can ↑, ↓ or alternate ↑/↓ Psychosocial factors Anxiety, depression, adverse experiences, dysregulated stress response Brain can alter normal reflexes of enteric nervous system (e.g. via hypothalamic stress hormone release) ↑ Activity of sensory receptors in gut + recruitment of formerly ”silent” receptors Altered visceral bowel sensation Visceral hypersensitivity Complex mechanisms ↓ Brain’s ability to modulate pain signals from gut; ↑ vigilance to pain Irritable Bowel Syndrome Disorder of brain-gut interaction with gastrointestinal manifestations Not a predominantly inflammatory condition During times of ↑ bowel motility: No lesions in gut mucosa (Absence of ”red flags” for organic disease) ↑ Impacts of other factors that precipitate diarrhea Dietary sensitivity (e.g. to intake of fermentable oligo/di/ monosaccharides and polyols— FODMAPs—which draw water into gut lumen by osmosis) ↑ Impacts of other factors that precipitate constipation Dietary sensitivity (e.g. to inadequate intake of motility- promoting fibre) During times of ↓ bowel motility: ↑ Time for water absorption from feces and bacterial fermentation ↑ Hard stool and trapped gas in bowel ↑ Number and sensitivity of active pain receptors (nociceptors) in gut Hyperalgesia ↑ Response to painful stimulus Stretch receptors in gut stimulate pain in normally unconscious neural pathways Allodynia Pain in response to normal stimulus ↑ Peristalsis ↓ Time for water absorption from feces ↑ Water volume in gut lumen ↑ Stretch / stimulation of visceral afferent nerves in gut Absence of bloody stool and anemia Absence of nocturnal symptoms and inflammatory markers Constipation Bloating Diffuse abdominal pain All symptoms may exacerbate psychosocial factors Bowel distension Diarrhea Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published April 30, 2022 on www.thecalgaryguide.com

abnormal-uterine-bleeding-aub-pathogenesis-and-clinical-findings

Abnormal Uterine Bleeding: Pathogenesis and clinical findings Authors: Joshua Yu, Karen Paik Reviewers: Ayaa Alkhaleefa, Parker Lieb, Hypothyroidism Hypothalamus senses ↓ serum thyroxine ↑Thyrotropin releasing hormone (TRH) release from hypothalamus ↑Prolactin (see Feedback Loop: Prolactin) Exogenous estrogen (e.g. estrogen-only birth control) ↑ Peripheral adipose tissue ↑ Aromatase (enzyme present in adipose tissue) ↑ Conversion of androgens to estrogens (aromatization) Excessive stress, exercise, low body mass (mechanism unclear) ↓ Hypothalamic gonadotropin releasing hormone secretion ↓Luteinizing hormone and follicle stimulating hormone release from pituitary ↑ Estrogen Heavier bleeding Angiogenesis in tumour tissue Polycystic ovarian syndrome (see slide) Pelvic inflammatory disease Immature hypothalamic- pituitary-ovarian axis (an immature axis is transient in most females) ↓ Positive feedback of estrogen in late follicular stage No LH surge Adenomyosis (endometrial tissue grows into uterus muscular wall) Endometrial polyps Retained products of contraception Infection Inflammation of endometrium Endometrium is more fragile Anovulatory Bleeding Leiomyoma (benign tumour in myometrium) Tara Shannon, Hannah Yaphe, Dr. Sarah Glaze* * MD at time of publication Ovarian Scarring Foreign bodies Intrauterine device perforation Physical trauma Impaired follicle maturation Anovulation Corpus luteum does not form No ovarian progesterone production ↑ Estrogen to progesterone ratio Proliferative effect of estrogen unopposed Endometrial proliferation No progesterone to organize growing endometrium Disorganized endometrium overgrows and sloughs off Irregular bleeding Menopause Premature ovarian insufficiency Intermittent congestion of polyp blood supply Transient ischemia and slight polyp necrosis Altered growth factor production Vascular dysregulation and leakier vessels Coagulopathies (e.g. von Willebrand disease) Impaired hemostasis Invasion of normal tissue ↓ Estrogen (hypoestrogenism) Atrophy of endometrium and vulvovaginal tissue Dry endometrial surfaces (↓ fluid to prevent friction) Endometrial carcinoma Micro- erosions of epithelium Inflammation Evidence unclear Heavier and more irregular bleeding Spotting Heavier and more irregular bleeding Light bleeding and spotting Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published May 2, 2022 on www.thecalgaryguide.com

rhumatisme-psoriasique-pathogenese-et-resultats-cliniques

rhumatisme-psoriasique-pathogenese-et-resultats-cliniques Psoriatic Arthritis: Pathogenesis and clinical findings Auteur: Payam Pournazari Rédacteurs: Yan Yu Scott Rapske Liam Martin* Traducteurs: Dianne Ganeswaran Stephen Williams Sylvain Coderre* * MD au moment de publication Note: L’arthrite rhumatoïde peut survenir avant ou après le psoriasis (la pathogenèse est la même). Augmentation de l’activité ostéoclastique Érosion de l’os sous- chondral mais formation de nouvelle osseuse ailleurs dans l’articulation Radiographie: la périostite; les syndesmophytes, érosions, déformation du crayon en godets (les articulations IP), ankylose des articulations IP HLA B27, Cw6 et d’autres sous- types Antécédents familiaux positifs Activation des cellules T (mécanisme inconnu) Infiltration du tissu synovial de l’articulation par les cellules T et B, cellules tueuses naturelles et les macrophages Production augmentée des molécules inflammatoires (les facteurs de nécrose tumorale [TNFs], les interleukines, etc.) qui agissent de façon systémique (dans tout le corps) Dans les tendons et le tissu conjonctif Inflammation des enthèses et du tissu conjonctif provoque le gonflement Dans la peau Réaction immunitaire détruisant les structures de la peau et des ongles (Voir diapositive Psoriasis) Le psoriasis en plaques sur la peau, dépressions punctiformes, onychorrhexie, taches d’huile, onycholyse, décoloration et hyperkératose Angiogenèse et vascularite dans les vaisseaux sanguins de la membrane synoviale Dans les articulations Les cytokines inflammatoires stimulent les nocicepteurs locaux 1. Oligoarthrites - asymétriques 2. Arthrite des articulations IPD 3. Polyarthrite rhumatoïde - symétrique 4. Atteinte axiale (raison inconnue, probablement en raison de « biomécanique », « innervation », et « vascularisation ». 5. Arthrite mutilante (grave et destructrice) L’enthésite (Douleur/sensibilité à l’insertion du ligament dans l’os) La dactylite (Inflammation de tout le doigt – les tissus mous et les articulations sont enflammés Légende: Physiopathologie Mécanisme Signe/Symptôme/Résultats de Laboratoire Complications Publié 10 November 2012 sur www.thecalgaryguide.com

acute-cholecystitis

Acute Cholecystitis: Pathogenesis and clinical findings Gallstone blocks the cystic duct, backing up bile into the gallbladder Gallstones causing physical trauma to gallbladder wall Irritation of adjacent diaphragm, stimulates phrenic nerve (C3-C5) Activates stretch receptors of visceral peritoneum, stimulates foregut autonomic nerves (T5-T8) Inflammatory mediator (i.e. prostaglandin) release by gallbladder and systemic inflammatory response Thickened gallbladder wall on ultrasound (gold standard test) On inspiration, the diaphragm pushes the gallbladder downward Irritation of parietal peritoneum, stimulates somatic nerves ↑ Permeability of vessels with systemic inflammation, which leak fluid from the blood into the interstitial space Radiating pain to the back and right shoulder Dull, diffuse abdominal pain referred to the epigastric region Fever, nausea/vomiting, tachycardia Positive Murphy’s sign (pain upon palpation of right upper quadrant [RUQ] on inspiration) Persistent RUQ pain, abdominal guarding and peritoneal signs Dehydration Authors: Yan Yu, Vina Fan Reviewers: Dean Percy, Mirna Matta, Crystal Liu, Ben Campbell Maitreyi Raman* * MD at time of publication Inflammation self-perpetuates Irritation of inner gallbladder wall/mucosa ↑ Gallbladder lumen pressure Intraluminal pressure exceeds arterial pressure ↓ Blood flow to gallbladder Gallbladder ischemia Local inflammation, loss of gallbladder mucosal integrity Bacterial invasionàtransmural inflammation of gallbladder Without treatment, prolonged ischemia and inflammation of the gallbladder Gallbladder gangrene (20%) Gallbladder perforation (20%) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published August 4 2019, updated May 16 2022 on www.thecalgaryguide.com

clostridium-difficile-infection-pathogenesis-and-clinical-findings

Clostridium difficile (C. diff) Infection Authors: Ryan Brenneis, Sravya Kakumanu Reviewers: Yoyo Chan, Sean Doherty, Vina Fan, Ben Campbell, Dr. Steve Vaughan*, Dr. Sylvain Coderre* * MD at time of publication Community exposure Infected close contacts Nosocomial exposure (most common) Poor hand hygiene and sanitization of surfaces and medical equipment Nosocomial risk factors Any antibiotic use (Especially clindamycin, fluoroquinolones, penicillins, cephalosporins) ↑ Antibiotic resistant strains Presence of pre-disposing risk factors (Note: do not need to be present for infection) Recent GI surgery Chemotherapy that has antimicrobial and immunosuppressive effects Usage of medications that reduce stomach acid (↑ pH) ↑ C. diff spores on surfaces and personnel Contact exposure Environmental exposure to C. diff carriers Inoculation of GI tract Disruption of normal gut microbiome allowing C. diff overgrowth Comorbidities (>65 years old, cirrhosis, inflammatory bowel disease, enteral feeding, obesity) via fecal-oral route Clostridium difficile Infection of GI Tract Spores unaffected by antibiotics germinate post-antibiotic treatment Infection recurrence Pseudomembranous colitis on endoscopy (colonic ulcerations potentially seen with severe infection) Hypotension Acute kidney injury Release of C. diff toxin A and B inactivates Rho and Ras GTPases in colonic epithelial cells (colonocytes) (Rho and Ras GTPases control cytoskeletal dynamics and gene expression) Cytoskeletal disorganization and arrest of RNA synthesis causes necrosis of colonocytes and triggers host immune response Neutrophil chemotaxis and activation ↑ Inflammation of colon Disruption of tight junctions between colonocytes Release of fluid into intestinal lumen and inability of colon to reabsorb it Toxic megacolon Bowel perforation Bloody stool (<10% of patients) Abdominal cramps Large bowel dilation from muscle paralysis Inflammation and destruction of underlying smooth muscle Breakdown of colonocyte cell membranes Inflammation of visceral peritoneum Volume depletion Watery diarrhea: ↑ frequency, small volume Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published March 30, 2019, updated May 16, 2022 on www.thecalgaryguide.com

constatations-classiques-de-sclerose-en-plaques-sep-sur-irm-cerebrale

Constatations classiques de sclérose en plaques (SEP) sur IRM cérébrale Auteurs: Evan Allarie Davis Maclean Viesha Ciura* Rédacteurs: Yan Yu* Traducteurs: Liana Martel Eddy Lang* * MD au moment de la publication Infiltrations dans la région infratentorielle Perte de la densité neuronale/axonale dans la région affectée, remplacée par une gliose au fil du temps Remarque : les constatations peuvent varier. Les constatations présentées ici ne sont pas exhaustives, mais constituent certaines des zones les plus fréquemment mises en évidence par l'IRM du cerveau dans la SEP. Les sites les plus communément observés sont : les régions juxtacorticales, périventriculaires, infratentorielles, la moelle épinière et le nerf optique. Cependant, les lésions peuvent apparaître partout où il y a de la myéline dans le SNC. L'inflammation et la destruction actives permettent au contraste de gadolinium de traverser la barrière hémato-encéphalique, ce qui peut être visualisé comme un marqueur de l'inflammation active dans la SEP Lésion classique du nerf optique (CN II) en cas de névrite optique. Rehaussement par Gadolinium (↑ intensité du signal de la lésion après l’injection de gadolinium) sur cette image en T1 démontre une inflammation active Image Credits: Dr. Viesha Ciura Pour plus de détails sur la pathogenèse, voir la diapositive du Guide de Calgary: Multiple Sclerosis (MS): Pathogenesis and Clinical Findings Inflammation dans le système nerveux central (SNC) Les cellules T, les cellules B et les macrophages infiltrent le SNC Infiltration se produit autour des veinsàinflammation locale Infiltrats périveineux autour des veines médullaires (perpendiculaires aux ventricules) Inflammation et destruction de la barrière hémato-encéphalique ↑ liquide inflammatoire extravasculaire autour des lésions, qui apparaît hyperintense/brillant Lésions s’étendent autour des veines, créant les lésions ovoïdes charactéristiques Plaques hyperintenses perpendiculaires périventriculaires classiques en T2/FLAIR suivant les veins médullaires – ‘Doigts de Dawson’ Lésion hyperintense du pédoncle cérebelleux moyen en T2/FLAIR dans une localisation classique de la SEP Légende: Physiopathologie Mécanisme Signe/Symptôme/Résultats de Laboratoire Complications Publié 25 octobre 2020 sur www.thecalgaryguide.com

pleural-effusions-pathogenesis-and-anterior-posterior-chest-x-ray-findings

Pleural Effusions: Pathogenesis and Anterior-Posterior Chest X-Ray Findings Decubitus chest x-ray view causes fluid to accumulate on ipsilateral side. (Most sensitive view for small effusions) Excess fluid accumulation within pleural space that is gravity- dependent/free- flowing Large accumulation of fluid pressing against lung tissue and mediastinum Fluid layering (i.e. opacification) between lung and chest wall Author: Sravya Kakumanu Reviewers: Reshma Sirajee, Tara Shannon *Stephanie Nguyen, *Shelley Spaner * MD at time of publication Transudative pleural effusion *See Pathogenesis and Clinical Findings of Transudative Pleural Effusions slide Exudative pleural effusion *See Pathogenesis and Clinical Findings of Exudative Pleural Effusions slide Fluid accumulation at bottom of pleural space in anterior- posterior chest x- ray Lung atelectasis (lung collapse) Fluid is denser than air and appears white on x-ray ↓ Pressure and occupied space in thoracic cavity Meniscus sign (concave line above opacification) Opacification of affected pleural space Blunting of costophrenic angles Diaphragmatic silhouette sign (sharp diaphragm edge obscured by fluid) Mediastinal shift towards atelectic lung Contralateral mediastinal shift (when no lung atelectasis) Contralateral tracheal deviation Pleural infections ↑ Inflammation at infection site à↑ permeability of parietal pleura endothelium Bacterial invasion into pleural space from pulmonary parenchyma ↑ Migration of neutrophils and release of inflammatory cytokines in pleural space Inflammation ↑ activation of coagulation cascade and ↓ fibrinolytic activity ↑ Deposition of fibrin clots/membranes within pleural space creating septations Loculated pleural effusion/empyema (fluid stuck within septations within the pleural space) Opacification does not follow gravity Effusion does not move in decubitus view Pleural thickening (whitening of lung perimeter from fibrin deposition - more visible on CT scan) More rounded margins with chest wall/fissures Note: ~175-500mL of fluid may need to accumulate before being visible on an Anterior-Posterior Chest X-Ray Image credit: https://radiopaedia.org/cases/pleural-effusion-7 Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published May 22, 2022 on www.thecalgaryguide.com

gout-pathogenesis-of-x-ray-findings

Gout: Pathogenesis of X-Ray findings Authors: Omer Mansoor, Nameerah Wajahat Reviewers: Reshma Sirajee, Tara Shannon *Stephanie Nguyen, *Shelley Spaner *MD at time of publication Hyperuricemia See hyperuricemia slide for mechanism ↑ Uric acid concentration in blood leaks into joints as monosodium urate (MSU) crystals Uric acid crystallizes due to lower temperature, change in pH, mechanical stress and other synovial factors Crystals found more commonly in 1st MTP joint > ankle > wrist MSU deposits within the bone producing intra-osseus tophi (stone-like deposits of crystals) MSU deposits in soft tissue and bone ↑ Inflammatory marker recruitment causes granulomatous inflammation Osteoclasts (↑ bone resorption) are activated, and osteoblasts (↑ bone formation) are inhibited at site of inflammation Marked localized bone loss ‘Rat Bite’ erosions Intra-osseus bone lesion (rare and non-specific for gout) Joint effusions may be seen on x-ray as an early finding in the acute phase of gout Soft Tissue Tophi (appear cloudy and can hide other x-ray findings) Normal bone density and preserved joint space (until late in the disease) Overhanging sclerotic margins Bone remodelled in an outward fashion to create the edge Punched out lytic bone lesions Appear as circular ‘hole punches’ in bone Note: Repeated episodes of gout must occur for 5 to 10 years before most joint changes may be seen on x-ray Image credit: Radiopaedia Legend: Pathophysiology Mechanism Sign/Radiographic Findings Complications Published June 7, 2022 on www.thecalgaryguide.com

Epilepsy Pathogenesis

Epilepsy: Pathogenesis Genetic susceptibility Angelman syndrome, Fragile X syndrome, Tuberous sclerosis, neurofibromatosis Chromosomal abnormalities cause abnormal neural patterns Neural Cerebral palsy, focal cortical dysplasia Malformation of cortical development Cerebrovascular Intracranial hemorrhage, ischemic stroke Other Acquired Head trauma, cerebral infection (i.e., HSV1, VZV, cysticercosis) Neoplasm Metabolic Inborn errors of metabolism Inherited enzyme deficiencies Neurodegenerative Alzheimer’s Disease Protein-rich plaque build-up and brain atrophy Inflammation and formation of scar tissue irritates neural tissue Infiltration of mass, grey matter irritation Damage to the brain and subsequent alteration of neuronal circuitry Neurotransmitter imbalances (i.e. ↑ glutamate, ↓ GABA, ↓ serotonin, ↓ dopamine, ↓ noradrenaline) Abbreviations: • HSV1 – Herpes Simplex Virus 1 • VZV – Varicella Zoster Virus ↑ Inflammatory cytokines (e.g. interleukin-6, tumor necrosis factor-α) Altered neurogenesis and gliosis Ion channel and receptor dysfunction causes imbalance of ion channel charges Authors: Keerthana Pasumarthi Christopher Li Reviewers: Negar Tehrani, Ephrem Zewdie, Ran (Marissa) Zhang, Carlos R. Camara-Lemarroy* * MD at time of publication Neurons fire in burst activity (referred to as paroxysmal depolarization shift) and often in groups (hypersynchrony) Abnormal neural activities eventually create self-reinforcing circuits and transform neural network over time Injuries from falls, bumps, operating heavy machinery Involuntary contractions Loss of consciousness Post-ictal confusion Recurrent seizures Sudden Unexplained Death of Epilepsy Patient (SUDEP) Loss of airway reflexes Aspiration of saliva or food contents Aspiration Pneumonia Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published July 5, 2022 on www.thecalgaryguide.com

Cervical Insufficiency

Cervical Insufficiency: Pathogenesis and clinical findings Cervical lacerations Cervical loop Cone biopsy electrosurgical procedure excision procedure Cervical procedures Post-procedure cervical re-modelling ↓ Structural collagen in extracellular matrix Opened cervix allows for ↑ voiding of vaginal skin cells, bacteria, mucous and fluid Fetal head moves lower into pelvis, exerting pressure on pelvic ligaments Hysteroscopy dilatation and curettage Antepartum Sterile intra-amniotic infection inflammation Inflammatory cascade within cervix ↑ Local myometrial and cervical prostaglandins/ cytokines ↑ Collagenase and leukocyte elastase increases break down of collagen Congenital abnormality of collagen synthesis Ex. Ehler-Danlos syndrome ↑ Vaginal discharge Change in color of vaginal discharge Braxton-Hicks-like contractions Menstrual-like cramps Back ache ↓ Cervical tensile strength and rigidity Cervical Insufficiency Spontaneous dilation and thinning of cervix Unknown cause Prolapsed fetal membranes Second trimester loss or preterm birth Risk of recurrent second trimester loss or preterm birth Authors: Kiera Pajunen Reviewers: Ran (Marissa) Zhang Brianna Ghali Ingrid Kristensen* * MD at time of publication Debris seen in amniotic fluid on U/S Short cervix (<2.5cm on trans-vaginal ultrasound) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published July 5, 2022 on www.thecalgaryguide.com

exudative-pleural-effusions-pathogenesis-and-lab-findings

Exudative Pleural Effusions: Pathogenesis and Lab Findings Authors: Sravya Kakumanu Reviewers: Ben Campbell *Tara Lohmann * MD at time of publication Chylothorax Damage to thoracic duct Leakage of lymphatic fluid into pleural space Pulmonary embolism Clot obstructs blood flow to lung Infarcted lung tissue Lung infection (e.g. pneumonia, tuberculosis) Lung infection signals inflammatory response Systemic Lupus Rheumatoid Erythematosus (SLE) arthritis (RA) Autoimmune antibodies localize to pleura Pleural tumors (primary or secondary from metastatic cancer) Inflammatory cells migrate to affected site and release cytokines ↑ Permeability of pleural capillaries ↑ Fluid leakage across capillaries Exudative Pleural Effusion Cancer invades lymphatic drainage of pleural space (PS) ↓ Drainage of pleural fluid (PF) from pleural space If infectious etiology Tumor invasion = inflammatory response See Pleural Effusions: X-ray Findings and Physical Exam Findings of Lung Diseases slides ↑ Permeable pleural capillaries allow ↑ protein and cell leakage into pleural space If pleural tumour: Release of cancer cells into pleural space Cancer cells on PF cytology 60-75% sensitive for malignancy If rheumatoid arthritis: Release of auto-antibodies into pleural space Auto-antibodies initiate inflammatory response in pleural space ↑ Inflammatory cells have ↑ glucose metabolism in pleural space Sterile PF with mildly elevated white blood cells, normal pH, normal glucose ↑ Inflammation at infection site damages endothelium of pleura Pleural Infection Stage I: Simple Parapneumonic Effusion ↑ Inflammatory cells and bacterial cells in pleural space have ↑ glucose metabolism in pleural space Bacterial invasion from infected parenchymaà pleural space < 40mg/dL glucose in PF ↑ Activation of coagulation cascade and ↓ fibrinolytic activity ↑ Deposition of fibrin clots/membranes within pleural space creates loculated effusion (compartmentalized effusion due to septations in pleural space) ↑ Production of lactate dehydrogenase (LDH) (LDH maintains NAD+ supply during ↑ glucose metabolism) ↑ CO2 production pH of PF < 7.20 ↑ CO2 production pH of PF < 7.20 < 3.3mmol/L glucose in PF Pleural Infection Stage II: Complicated Parapneumonic Effusion Loculated effusion OR bacteria present OR ↓ pH + ↓ glucose ↑ Fibroblast proliferation creates thickened pleura ↑ Pus in pleural space Pleural Infection Stage III/Empyema: Loculated effusion and pus in pleural space PF/serum protein ratio ≥ 0.5 PF/serum LDH ratio ≥ 0.6 Light’s Criteria: Any criteria can be met to be an exudative pleural effusion PF LDH ≥ 2/3 upper limit of normal Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published August 9, 2022 on www.thecalgaryguide.com

presentation-of-sah

Subarachnoid Hemorrhage: Clinical Findings Sudden bleeding into space surrounding the brain (for pathogenesis, see Subarachnoid Hemorrhage: Pathogenesis) Authors: Jason An, M. Patrick Pankow Reviewers: Owen Stechishin, Dave Nicholl, Haotian Wang, Hannah Mathew, Ran (Marissa) Zhang, Yan Yu*, Cory Toth* * MD at time of publication Bleed into subarachnoid space Subarachnoid Hemorrhage (SAH) Posterior hypothalamus ischemia (↓ Blood flow and oxygen) Red blood cell lysis from energy depletion or complement activation Release of spasmogens (spasm inducing agents) Cerebral vasospasm (narrowing of arteries from persistent contraction) ↓ blood flow Cerebral ischemia Release catecholamines (hormones from the adrenal gland; e.g., epinephrine, norepinephrine) ↑ Intracellular calcium Release of antidiuretic hormone Antidiuretic hormone acts on the distal convoluted tubule and collecting duct in kidney to reabsorb water Dilution of serum sodium Hyponatremia (low blood sodium levels) Release of epileptogenic (potential seizure causing agents) into cerebral circulation Seizure Products from blood breakdown in cerebral spinal fluid Irritation of meninges (membranes surrounding the brain) Aseptic meningitis (non-infectious inflammation) Meningismus (neck pain + rigidity) Cerebral infarction (death of tissue) Obstructs cerebral spinal fluid flow and absorption at subarachnoid granulations Hydrocephalus (fluid build up in ventricles) ↓ Level of consciousness Reduced cerebral blood flow Dilation of cranial vessels to ↑ blood flow Rapid ↑ internal carotid artery intracranial pressure Refer to Increased Intracranial Pressure: Clinical Findings slide Internal carotid artery Pituitary ischemia Hypopituitarism [underactive pituitary gland, failing to produce 1+ pituitary hormone(s)] Refer to hypopituitarism slides Myocardial disruption Left ventricle dysfunction ↑ Pressure in left heart Blood forced backwards into pulmonary veins ↑ Pulmonary blood pressure Fluid from blood vessels leaks into lungs Dysrhythmias (disturbance in rate/rhythm of heart) causing ↓ cardiac output Syncope (loss of consciousness due to ↓ blood flow to the brain) Pulmonary edema (excess accumulation of fluid in lung) Cerebral hypoperfusion Sudden ↑in blood volume Vessels and meninges suddenly stretch Thunderclap Headache (worst headache of patient's life) Shortness of breath Reactive cerebral hyperemia (excess blood in vessels supplying the brain) Artery specific findings: Rapid ↑ internal carotid artery intracranial pressure Middle cerebral artery Posterior communicating artery Compression of outer CN3 Compression of inner CN3 Anterior communicating artery Nonreactive pupil Gaze palsy (eye deviates down and out) Diplopia (double vision) Ptosis (drooping of upper eyelid) Frontal lobe ischemia Avolition (complete lack of motivation) Ischemia of motor strip pertaining to the legs Bilateral leg weakness Motor strip ischemia Hemiparesis (weakness/ inability to move one side of the body) Ischemia of parietal association areas (brain regions integral for motor control of the eyes, the extremities and spatial cognition) Aphasia (impaired ability to speak and/or understand language)/ neglect Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published July 1, 2014, updated August 10, 2022 on www.thecalgaryguide.com

thrombose-veineuse-profonde-soupconne-tvp-pathogenese-et-complications

Thrombose veineuse profonde soupçonné (TVP) Auteurs: Dean Percy Yan Yu Rédacteur: Tristan Jones Julia Heighton Man-Chiu Poon* Lynn Savoie* Traducteurs: Sophia Shah Sylvain Coderre* *MD à la publication La grossesse, contraceptifs oraux Pathogénèse et complications Activation plaquettaire ↑ formation de caillots Maladies héréditaires Anomalie congénitale de la coagulation (p.e. facteur V Leiden, facteur II muté, déficit en protéine S/C) ↑ capacité de coagulation Notes: • TVP provoque une embolie pulmonaire, le thrombus artériel provoque un accident vasculaire cérébral • TVP précédente est un facteur de risque de TVP courante Malignité Libération anormale de cytokines favorisant la coagulation Traumatisme/opération Blessure systémiqueà activation de la cascade de coagulation État d'hypercoagulabilité↑ capacité du sang à coaguler lors de la stimulation Oestrogène favorise l'hypercoagulabilité, surtout en présence d'autres risques Hypertension Bactéries Valve artificielle Endommage les parois des vaisseaux Adhèrent/ envahissent / vaisseaux Surface anormale Blessure de vaisseau Expose le facteur tissulaire sur les cellules endommagées /sous-endothélium pour la liaison au FvW Triade de Virchow Stase veineuse ↓ débit sanguins au site de la lésion vasculaireà concentration des facteurs de coagulation sanguine sur ce site La graisse contient plus d'aromatase: ↑ d'androgènesà œstrogènes mode de vie sédentaire, mauvais retour veineux Obésité Les caillots se produisent généralement dans les veines des jambes 1. Les veines larges et profondes permettent l'accumulation de sang 2. Retour veineux des jambes est contre la gravité 3. Valves dans les veines des jambes enclins au refoulement ↓ mouvement musculaire = ↓ débit sanguin Fracture, immobilisation, alitement, long tour d’avion/ de véhicule Destruction de la valve veineuse par un caillot Insuffisance veineuse Les caillots empêchent le sang à retourner au cœur. L'accumulation de sang dans une jambe entraîne l’œdème unilatéral et l’inflammation veineuse (rougeur, chaleur, sensibilité) Le caillot s'embolie dans les poumons Thromboembole -*Embolie pulmonaire (complication aiguë mortelle) - Hypertension pulmonaire thromboembolique chronique Légende: Physiopathologie Mécanisme Signe/Symptôme/Résultats de Laboratoire Complications Publié 15 juin 2019 sur www.thecalgaryguide.com

alcoholic-fatty-liver-disease-pathogenesis-and-clinical-findings

Alcoholic Fatty Liver Disease: Pathogenesis and clinical findings Authors: Tara Shannon Reviewers: Ben Campbell, Yan Yu*, Samuel Lee* * MD at time of publication ↑NADH:NAD+ ratio in hepatic cells, a “high energy state” marker in the cell When a cell is in a high energy state, metabolic processes that provide energy are inhibited ↓ β-oxidation (break down) of triglycerides in the liver Abbreviations: • CYP2E1 – Cytochrome P450, subtype 2E1 • NADH/NAD+ – Nicotinamide Adenine Dinucleotide (in reduced and oxidized form respectively) Ethanol upregulates hepatic cell fatty acid transporters such as fatty acid transport protein 1 and 5 (FATP1,5) ↑ Fatty acid transporters in hepatic cells ↑ Uptake of free fatty acids from circulation into hepatic cells Alcohol (ethanol) consumption Ethanol is primarily metabolized in the liver by enzymes alcohol dehydrogenase (ADH) and CYP2E1 ADH converts ethanol into acetaldehyde & NADH CYP2E1 converts ethanol into acetaldehyde Excessive alcohol consumedàthe liver cannot process ethanol and its metabolites quickly enoughà ethanol, acetaldehyde, and NADH accumulate in the liver and may enter the bloodstream Acetaldehyde is a highly reactive and unstable molecule that can damage proteins, enzymes, and DNA (Hepatic stellate cells (HSC) are sensitive to liver damage and release cytokines when activated) Acetaldehyde activates HSCàHSC release tumor necrosis factor alpha (TNF-!), an inflammatory markerà↑ liver inflammation Acetaldehyde upregulates the production of enzymes required for fatty acid synthesis TNF-! stimulates fat production in liver cells TNF-! enters circulation and stimulates adipose cells to break down, releasing triglyceride stores as free fatty acids ↑ Free fatty acids released into circulation Liver biopsy shows liver inflammation TNF-! causes the production of reactive oxygen species (unstable, highly reactive molecules) Reactive oxygen species cause oxidative damage to hepatic cells’ mitochondria Damaged mitochondria can no longer efficiently perform metabolic tasks ↑ Building blocks, catalysts, and direct stimulating factorsàliver cells ↑ fat production ↑ Lipogenesis in the liver (triglyceride production) ↑ Triglyceride accumulation in liver cells Triglyceride-rich droplets in hepatic cells change the cells’ physical properties compared to normal liver cells, allowing imaging modalities to exploit these differences to detect lipid infiltration Fatty livers appear darker on CT scans Liver biopsy shows triglyceride- rich droplets inside liver cells Fatty livers appear brighter and with poorer visualization of structures (like bile ducts and vessels) on ultrasounds Imaging such as ultrasound, CT, and MRI can visualize and quantify liver fat Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published August 21, 2022 on www.thecalgaryguide.com

patellar-tendon-rupture-pathogenesis-and-clinical-findings

Patellar Tendon Rupture: Pathogenesis and clinical findings Author: Molly Joffe Reviewers: Liam Thompson, Alyssa Federico, Tara Shannon, Gentson Leung* *MD at time of publication Chronic disease (e.g. renal failure, gout, rheumatoid arthritis, and diabetes) Repetitive activities involving rapid knee flexion and extension Tendon inflammation and micro-tearing Fluoroquinolone (antibiotic class) use Smoking Immobilization of knee ↓ Muscle and tendon flexibility and strength Steroid use (including intraarticular injections) Changes in collagen fibrils composing tendon (exact mechanism unknown) Disrupted blood supply to tendon and poor healing Compromised integrity and strength of the tendon Sudden heavy load on flexed knee while foot is planted Quadriceps muscles contract while lengthening (eccentric contraction)àforce exceeds tendon strength Patellar tendon innervated by common peroneal (fibular) nerve Nociceptors (pain receptors) within tendon activated by tendon rupture Pain and tenderness below the patella Collagen fibres in tendon tear Tearing or popping sensation at time of injury Patellar Tendon Rupture Tendon/Ligament detaches from bony attachment on patella or tibial tubercle No connection of quadriceps to tibia via patellar tendon ↑ Force on tibial tubercle during tendon detachment Avulsion fracture of tibial tubercle Trauma to tendon ruptures surrounding blood vessels Coagulation cascade and inflammatory mediators released at rupture site Quadriceps muscles unable to stabilize patellar tracking Instability of knee joint Quadriceps muscle tension pulls patella upwards with no resistance from patellar tendon Patellar tendon cannot use distal attachment site for leverage Knee extensor muscles unable to effectively contract Knee buckling Abnormal gait Patella alta (high sitting patella) on X-ray Palpable gap below the patella Bruising below the patella Swelling below the patella ↑ Risk of falls Loss of patellar reflex Inability to perform a straight leg raise (hip flexes and knee cannot remain straight) Hematoma (blood collection under the skin) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published August 28, 2022 on www.thecalgaryguide.com

medial-epicondylitis-golfers-elbow-pathogenesis-and-clinical-findings

Medial Epicondylitis (Golfer’s Elbow): Pathogenesis and clinical findings Intrinsic Factors: age, body weight, nutrition, gender, anatomical variations, joint laxity, systemic disease, muscle weakness / imbalance, vascular perfusion Micro-tears within flexor-pronator tendons initiating healing process: inflammation, proliferation, and remodeling (see acute wound healing slide) Continued repetitive strains with inadequate recovery time between activitiesàhealing unable to meet tissue damage Authors: Brett Lavender Reviewers: Alyssa Federico, Liam Thompson, Tara Shannon, *Gerhard Nikolaus Kiefer * MD at time of publication Extrinsic Factors: activities involving repeated forceful use of the flexor-pronator muscle groups (sports including golf and baseball, activities such as shoveling, gardening or hammering nails) Ineffective revascularization of damaged tissue MRI or Ultrasound Findings: Tendon thickening, partial tears, disrupted vascular distribution +/- edema of surrounding tissues Disorganized collagen formation and scarring à↑ type III collagen (most common collagen involved with wound healing) ↑ Tendon thickening Decreased tensile strength of tendon Weakness of the flexor-pronator muscle groups ↑ Nerve growth within damaged tissue (consequence of healing response) Local nerves are compressed by thickened tendonànociceptors within tendon are activated (Ulnar nerve passes through cubital tunnel adjacent to medial epicondyle) Ulnar paresthesias may result to structures innervated distal to the cubital tunnel Medial Epicondylitis Tendinosis at the common flexor-pronator origin at the medial epicondyle of the humerus Pain with passive wrist extension or resisted flexion Tenderness over the proximal wrist flexor-pronator muscles Pain localized to medial epicondyle Severity ranges from mild to severe based on the effect on patient activities Mild tendinopathy: patient continues most activities with minor pain Moderate tendinopathy: patient continues some activities with modifications Severe tendinopathy: patient’s daily activities are impacted by severe pain Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published August 30, 2022 on www.thecalgaryguide.com

ascending-cholangitis-pathogenesis-clinical-findings

Ascending Cholangitis: Pathogenesis and clinical findings Authors: Brandon Hisey, Neel Mistry Reviewers: Alec Campbell, Vina Fan, Ben Campbell, Kelly Burak*, Eldon Shaffer* * MD at time of publication Reflux of biliary contents into the vascular system (cholangiovenous reflux) Bacteria ascends into biliary tract from duodenum via Sphincter of Oddi Gallstone in the common bile duct Stricture of biliary/hepatic ducts Biliary / pancreatic duct malignancy Biliary obstruction (partial bile duct obstruction) ↓ Excretion of bilirubin into bileà ↑ bilirubin in blood ↑ Serum bilirubin Deposition of bilirubin in the skin and mucous membranes Jaundice*† Parasites in bile duct (E.g. Clonorchis) Complication of endoscopic retrograde cholangiopancreatography (ERCP) Bile accumulates in biliary tract Bile duct dilation on ultrasound Sludge (bile precipitants) impact bile ducts worsening obstruction Obstruction & detergents in bile inflame ductal mucosa. Inflammation then spreads to adjacent structures Stimulates phrenic (C3-C5) and foregut autonomic nerves (T5-T8) Dull right upper quadrant pain*† radiating to back and right shoulder ↑ Intra-biliary pressure Impaired forward flowà ↑ backflow of bile Impaired bile secretion damages ductal epithelium of the biliary tract Damaged ductal epithelium leaks ALP and GGT (enzymes) into blood ↑ Serum ALP and GGT ↑ Permeability of bile ductules Reduced flushing of bile out to duodenum Inflammatory response triggered Fever*† ↑ WBCs Tachycardia Hypotension† Confusion† Oliguria Bacterial translocation from biliary tract into blood Bacteremia Massive systemic inflammatory response Septic Shock (see Distributive Shock slide) * Charcot’s triad ~20% of cases | † Reynolds’ pentad ~7% of cases Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications First published November 18, 2015; Updated August 31, 2022 on www.thecalgaryguide.com

acute-lower-gi-bleeds-pathogenesis-and-clinical-findings

Acute Lower GI Bleeds: Pathogenesis and Clinical Findings Diverticulosis Formation of diverticula (outpouchings of the bowel wall) Intestinal vessels are stretched over the domes of the diverticula Angiodysplasia Formation of dilated, thin- walled vessels in GI tract mucosa/ submucosa Colorectal Cancer Infectious Colitis Invasion of bacteria and/or bacterial toxins into intestinal wall Cell damage and cell death Sloughing off of intestinal epithelial cells Ischemic Colitis ↓ Blood flow to a portion of the colon Lack of oxygen delivery to colon wall Necrosis (cell death) in the colon wall Inflammatory Bowel Diseases (Note: these are chronic diseases and rarely present with acute lower GI bleed) New, extremely friable blood vessels develop within the tumor Malignant tissue invades the colon wall and disrupts colonic blood vessels Crohn Disease Immune- mediated full thickness inflammation of bowel wall Ulcer formation and disruption of intestinal vessels Ulcerative Colitis Recurrent immune- mediated inflammation of colon mucosa Authors: Miranda Schmidt Illustrator: Mizuki Lopez Reviewers: Vina Fan, Ben Campbell, Kerri Novak* * MD at initial time of publication Acute Lower GI Bleed ↑ Risk for vessel damage and rupture Blood travels rapidly through GI tract Hematochezia (bright red blood per rectum) May result in significant blood loss Blood from the small intestine or right colon travels a longer distance through the GI tract Bacteria in the GI tract has time to oxidize hemoglobin in the blood Oxidization makes blood a darker color Melena (rare in a lower GI bleed) (tarry black stool) Inferior Vena Cava Diaphragm Esophagus Loss of red blood cells results in a loss of hemoglobin (a component of red blood cells) Fluid from the extravascular space moves into the blood vessels to maintain vascular volume Fluid is administered in a healthcare setting to compensate for blood loss Hypovolemic Shock (rare in a lower GI bleed) (↓ Oxygen delivery to tissues due to low blood volume) See “Hypovolemic Shock” slide for signs and symptoms Lower GI Bleeds are intra-luminal GI tract bleeds that occur anywhere distal to the ligament of Treitz (transition between duodenum and jejunum) After 24 hours, the addition of fluid to the intravascular space dilutes hemoglobin in the blood Normocytic Anemia Duodenum Ligament of Treitz Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published August 31, 2022 on www.thecalgaryguide.com

lateral-epicondylitis-tennis-elbow-pathogenesis-and-clinical-findings

Lateral Epicondylitis (Tennis Elbow): Pathogenesis and clinical findings Authors: Brett Lavender Reviewers: Alyssa Federico, Liam Thompson, Tara Shannon Gerhard Nikolaus Kiefe* * MD at time of publication Extrinsic Factors: activities involving repeated forceful use of the extensor-supinator muscle groups (sports including tennis and squash, activities such as painting, carpentry or using certain hand tools) Intrinsic Factors: age, body weight, nutrition, gender, anatomical variations, joint laxity, systemic disease, muscle weakness / imbalance, vascular perfusion Micro-tears within extensor-supinator tendons initiating healing process: inflammation, proliferation, and remodeling (see acute wound healing slide) Continued repetitive strains with inadequate recovery time between activitiesàhealing unable to meet tissue damage Ineffective revascularization of damaged tissue MRI or Ultrasound Findings: Tendon thickening, partial tears, disrupted vascular distribution +/- edema of surrounding tissues Disorganized collagen formation and scarringà↑ type III ↑ Nerve growth within damaged tissue collagen (most common collagen involved with wound healing) (consequence of healing response) ↑ Tendon thickening Decreased tensile strength of tendon Weakness of the extensor- supinator muscle groups Lateral Epicondylitis Tendinosis at the common extensor-supinator origin at the lateral epicondyle of the humerus Local nerves are compressed by thickened tendon ànociceptors within tendon are activated Pain with passive wrist Pain localized to flexion or resisted extension lateral epicondyle Tenderness over the proximal wrist extensor-supinator muscles Severity ranges from mild to severe based on the effect on patient activities Mild tendinopathy: patient continues Moderate tendinopathy: patient continues Severe tendinopathy: patient’s daily most activities with minor pain some activities with modifications activities are impacted by severe pain Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published September 25, 2022 on www.thecalgaryguide.com

quadriceps-tendon-rupture-pathogenesis-and-clinical-findings

Quadriceps Tendon Rupture: Pathogenesis and clinical findings Author: Molly Joffe Reviewers: Liam Thompson, Alyssa Federico, Tara Shannon, Gentson Leung* *MD at time of publication Repetitive activities involving, rapid, active flexion and extension of the knee Quadriceps tendon inflammation and micro-tearing Immobilization of leg/knee Steroid use (including intraarticular injections) Quadricep muscles atrophy ↓ Quadricep muscle strength Smoking Chronic disease (e.g. renal failure, gout, rheumatoid arthritis, and diabetes) Fluoroquinolone (antibiotic class) use Changes in collagen fibrils composing tendonàimpaired tendon strength (exact mechanism unknown) Quadriceps tendon shortens ↓ Quadricep tendon flexibility Disrupted blood supply to quadriceps tendon and poor healing Compromised integrity of the quadriceps tendon and ↓ strength Sudden heavy load on flexed knee while foot is plantedàquadriceps muscles contract while lengthening (eccentric contraction) Force on quadriceps tendon exceeds its strength Quadriceps Tendon Rupture Tendon detaches from bony attachment on patella ↑ Force on patella during quadriceps tendon detachment Collagen fibres in quadriceps tendon tear No connection of quadriceps to tibia via quadriceps tendon Patellar tendon tension pulls patella downwards with no resistance from quadriceps muscles Quadriceps tendon innervated by common peroneal (fibular) nerve Nociceptors (pain receptors) within tendon activated by tendon rupture Pain and tenderness above the patella Trauma to tendon ruptures blood vessels Coagulation cascade and inflammatory mediators released at rupture site Quadriceps muscles unable to stabilize patellar tracking Knee joint instability Patella baja (low sitting patella) on X-ray Palpable gap above the patella Loss of patellar reflex Patellar tendon cannot use proximal attachment site for leverage Knee extensor muscles unable to effectively contract Inability to perform a straight leg raise (hip flexes while knee cannot remain straight) Bruising above the patella Swelling above the patella Avulsion fracture of patella Tearing or popping sensation at time of injury Knee buckling Abnormal gait ↑ Risk of falls Hematoma (blood collection under the skin) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published October 2, 2022 on www.thecalgaryguide.com

felty-syndrome

Felty Syndrome: Pathogenesis and clinical findings Authors: Anjali Arora Reviewers: Ben Campbell, Liam Martin*, Yan Yu* * MD at time of publication Longstanding chronic Rheumatoid Arthritis Rheumatoid Arthritis (RA): a disease of systemic autoimmunity – refer to Rheumatoid Arthritis slides for detailed pathogenesis Genetic susceptibility Presence of a specific type of Human Leukocyte Antigen (HLA-DR4), a surface protein on immune cells that is known to be associated with or worsen autoimmune activity Idiopathic autoimmunity Neutrophil activation, apoptosis and adherence to endothelial cells in the spleen Felty Syndrome An uncommon extraarticular manifestation of seropositive Rheumatoid Arthritis characterized by the triad of splenomegaly, neutropenia and arthritis Immunologic stress leads to proliferation of white pulp in spleen (responsible for initiating immune responses to foreign antigens) Splenomegaly ↑ RBC and platelet sequestration within the spleen leading to a quantitative shortage of these cells in circulation Enlarged spleen compresses stomach Loss of appetite Complex autoimmune phenomena lead to ↓ neutrophil production and ↑ removal from the circulating pool Neutropenia For a detailed mechanism, refer to Neutropenia slides ↓ Circulating neutrophils leads to ↑ susceptibility to infections Severe, untreated Rheumatoid Arthritis will lead to systemic inflammation See Rheumatoid Arthritis slides for detailed mechanism Chronic erosion of synovial membranes in joints commonly affecting the hands, wrists and knees Arthralgia (symmetric polyarthritis, usually with small joint distribution) Thrombocytopenia Refer to Thrombocytopenia slides for signs and symptoms Normocytic Anemia Refer to Normocytic Anemia slide for signs and symptoms Host becomes infected Fever Recurrent infections Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published October 18, 2022 on www.thecalgaryguide.com

microscopic-colitis-pathogenesis-and-clinical-findings

Microscopic Colitis: Pathogenesis and clinical findings Genetic Author: Tony Gu, Kayleigh Yang Reviewers: Yoyo Chan, Vina Fan, Ben Campbell, Dr. Edwin Cheng* * MD at time of publication Release of cytokines (e.g. interferon gamma (IFNγ)) Downregulation of intestinal tight junction proteins ↓ Epithelial barrier function ↑ Transmucosal permeability Infiltration of bacteria or antigens ↑ Expression of nuclear factor kappa B (NF-kB) in colonic epithelial cells NF-kB increases transcriptional activity in specific genes ↑ Inflammatory molecules (histamine, prostaglandins, and nitric oxide) in epithelium predisposition Unknown trigger ↑ Transforming growth factor beta 1 (TGF- β1) and vascular endothelial growth factor (VEGF) expression in colonic epithelial cells Equilibrium shift to more production of collagen (fibrinogenesis) than breakdown (fibrinolysis) Drug exposure (e.g., non- steroidal anti- (+) inflammatory drugs (NSAIDs), proton pump inhibitors (PPIs)) Inflammation and accumulation of immature subepithelial collagen matrix Subtype: Collagenous Colitis Intestinal mucosal inflammation Subtype: Lymphocytic Colitis characterized by a colonic subepithelial characterized by intraepithelial collagen band on histology lymphocytic infiltrates on histology Microscopic Colitis Intestinal epithelial damage Malabsorption of nutrients (including bile acids) Weight loss ↑ Intestinal transmucosal permeability Water drawn into lumen through osmosis Ions and water back leak into intestinal lumen Non-bloody watery diarrhea Dehydration and electrolyte disturbances Continuous release of inflammatory mediators Peripheral afferent nerve sensitization Visceral hypersensitivity Abdominal pain Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published December 8, 2018, Updated October 18, 2022 on www.thecalgaryguide.com

copd-findings-on-posterior-anterior-and-lateral-chest-x-ray-findings

Authors: Shayan Hemmati COPD: Findings on Posterior-Anterior and Lateral Chest X-ray Findings Reviewers: Reshma Sirajee, Sravya Kakumanu, Tara Shannon, *Stephanie Nguyen, *MD at time of publication Chronic Obstructive Pulmonary Disease (COPD) See Pathogenesis of COPD Slides Findings of COPD may not be apparent on chest X-ray early within the disease Lung inflammation causes proteolytic destruction of lung parenchyma (part of lungs involved in gas exchange) Alveolar walls are damagedàformation of fragile enlarged sacs of air called bullae Rupture of bullae due to weak alveolar walls Air leaves alveola and enters pleural space Pneumothorax See Primary Spontaneous Pneumothorax slide Vasoconstriction of pulmonary arteries to shunt blood to better ventilated areas Pulmonary hypertension See Pathogenesis of Pulmonary Hypertension slide ↑ Pressure within pulmonary arteries Enlargement of pulmonary arteries Hilar enlargement Lung hyperinflation (defined as 10 posterior ribs above the diaphragm level on the midclavicular line) ↑ Lucency of the lung field, ↓ lung markings (unless COPD is of chronic bronchitis phenotype) ↑ Size of retrosternal airspace ↑ Anterior – posterior (AP) diameter (“Barrel Chest”) Flattening of hemidiaphragms 12 3 4 5 6 7 8 9 10 Poorly ventilated areas of lung Hyperinflation as air becomes trapped in damaged lungs ↑ Total volume of air within the chest Airway fibrosisà bronchial wall thickening (yellow arrow heads) Air is less dense than soft tissue and vessels so it appears black ↑ Pressure anteriorly on sternum ↑ Pressure posteriorly on thoracic wall ↑ Pressure posteriorly on diaphragms PA Bullae sometimes visible on X-ray (focal areas of lucency with spread out vascular markings) Image credit: Bronchial wall thickening image courtesy of Dr. Ashley Davidoff Image credit: Radiopaedia Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published October 26, 2022 on www.thecalgaryguide.com

Granulomatosis with Polyangiitis Pathogenesis

Granulomatosis with polyangiitis: Pathogenesis Author: Oswald Chen Reviewers: Ben Campbell *Liam Martin * MD at time of publication Drugs Thiol- and hydrazine-containing medications (e.g., hydralazine, propylthiouracil, allopurinol) Environmental exposures Silica dust, cigarette smoke, infections (Staphylococcus aureus) Genetic factors Alpha-1 antitrypsin deficiency, proteinase 3 gene mutation ↑ Production of cytokines and antineutrophil cytoplasmic antibodies (ANCAs) (mechanism unknown) Cytokines bind to endothelial cells (that line blood vessels) and neutrophils, priming them Proteinase 3 (PR3), an enzyme that degrades extracellular matrix proteins, migrates from neutrophil granules to neutrophil cell surface Circulating ANCAs bind to PR3 on neutrophils PR3 stimulates maturation of dendritic cells in lungs Dendritic cells present antigen (PR3) to naïve CD4+ T cells in peripheral lymph nodes T cells differentiate into type 1 and type 17 helper T cells (Th1 and Th17 cells) Th1 and Th17 cells secrete cytokines (interferon γ (INF-γ) and tumor necrosis factor α (TNF-α)) in lungs Secreted cytokines trigger macrophage maturation Formation of granulomas (giant cells with central necrosis surrounded by plasma cells, lymphocytes, and dendritic cells) primarily in lungs and upper airways ANCA-activated neutrophils release proinflammatory cytokines, attracting more neutrophils to endothelium (blood vessel wall) ANCA-activated neutrophils undergo firm adhesion to endothelium ANCAs stimulate ↑ secretion of proteolytic enzymes and reactive oxygen species from neutrophils Endothelial damage and tissue injury Granulomatosis with polyangiitis (GPA) ANCA-associated vasculitis affecting medium and small-sized arteries, associated with necrotizing granulomas Constitutional symptoms with involvement of multiple organ systems (see slide on clinical findings) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published December 4, 2022 on www.thecalgaryguide.com Granulomatosis with polyangiitis: Clinical findings Inflammation-mediated endothelial damage and granuloma formation (see slide on pathogenesis) Granulomatosis with polyangiitis (GPA) Author: Oswald Chen Reviewers: Ben Campbell *Liam Martin * MD at time of publication ANCA-associated vasculitis affecting medium and small-sized arteries, associated with necrotizing granulomas Constitutional symptoms Fever, unintentional weight loss, night sweats, arthralgias Skin involvement Inflammation of cutaneous vessels Systemic inflammation obstructing blood flow, with granulomatous lesions primarily in upper airways and lungs Ear, nose, and throat involvement ↑ C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) (markers of inflammation) Necrotizing granulomas on biopsy of affected tissue Positive PR3-ANCA/c-ANCA blood test (antibodies present in ~90% of patients, described in GPA Pathogenesis slide) Renal involvement Inflammation of renal vessels Rupture of basement membrane (layer that filters blood from glomerular capillaries into Bowman’s capsule) Pauci-immune glomerulonephritis (see Nephritic Syndrome slide) Rapidly progressive glomerulonephritis Eye involvement Inflammation of ocular tissue Conjunctivitis Scleritis/ episcleritis (painful red eye) Lower respiratory tract involvement Inflammation of pulmonary vessels Vessel occlusion and ischemia Skin necrosis Vessels burst and blood pools under skin Round and retiform (net- like) palpable purpura of lower extremities Granulomatous destruction of nasal cartilage Collapse of nasal bridge Saddle nose deformity Inflammation of paranasal sinus and nasal cavity vessels ↓ Perfusion of lungs Dyspnea Damage to interstitial capillaries Hemoptysis Diffuse alveolar hemorrhage Rhinitis/ sinusitis Granulomatous obstruction of eustachian tube Otitis media (see Otitis Media slide) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published December 4, 2022 on www.thecalgaryguide.com

Granulomatosis with polyangiitis: Clinical findings

Granulomatosis with polyangiitis: Clinical findings Inflammation-mediated endothelial damage and granuloma formation (see slide on pathogenesis) Granulomatosis with polyangiitis (GPA) Author: Oswald Chen Reviewers: Ben Campbell *Liam Martin * MD at time of publication ANCA-associated vasculitis affecting medium and small-sized arteries, associated with necrotizing granulomas Constitutional symptoms Fever, unintentional weight loss, night sweats, arthralgias Skin involvement Inflammation of cutaneous vessels Systemic inflammation obstructing blood flow, with granulomatous lesions primarily in upper airways and lungs Ear, nose, and throat involvement ↑ C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) (markers of inflammation) Necrotizing granulomas on biopsy of affected tissue Positive PR3-ANCA/c-ANCA blood test (antibodies present in ~90% of patients, described in GPA Pathogenesis slide) Renal involvement Inflammation of renal vessels Rupture of basement membrane (layer that filters blood from glomerular capillaries into Bowman’s capsule) Pauci-immune glomerulonephritis (see Nephritic Syndrome slide) Rapidly progressive glomerulonephritis Eye involvement Inflammation of ocular tissue Conjunctivitis Scleritis/ episcleritis (painful red eye) Lower respiratory tract involvement Inflammation of pulmonary vessels Vessel occlusion and ischemia Skin necrosis Vessels burst and blood pools under skin Round and retiform (net- like) palpable purpura of lower extremities Granulomatous destruction of nasal cartilage Collapse of nasal bridge Saddle nose deformity Inflammation of paranasal sinus and nasal cavity vessels ↓ Perfusion of lungs Dyspnea Damage to interstitial capillaries Hemoptysis Diffuse alveolar hemorrhage Rhinitis/ sinusitis Granulomatous obstruction of eustachian tube Otitis media (see Otitis Media slide) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published December 4, 2022 on www.thecalgaryguide.com

Erythema multiforme (EM): Pathophysiology and clinical findings

Erythema multiforme (EM): Pathophysiology and clinical findings Infectious agents (cause >90% of EM) Herpes simplex virus types 1 and 2 Mononuclear cells transport herpes simplex virus DNA fragments to keratinocytes in epidermis Herpes simplex virus-specific CD4 T-cells of the immune system are recruited to the epidermis CD4 T-cells release interferon-gamma (a pro-inflammatory cytokine) in response to viral antigens in keratinocytes in the epidermis Lymphocytes infiltrate along the dermal-epidermal junction of the skin Lymphocytes create an inflammatory and edematous environment Keratinocytes irreversibly degenerate and undergo apoptosis and necrosis Formation of inflammatory epidermal lesions Authors: Ayaa Alkhaleefa Reviewers: Ben Campbell Damilola Omotajo Jori Hardin* *MD at time of publication Drugs (a rare cause of EM) Non-steroidal anti- inflammatory drugs i.e. diclofenac sodium Antibiotics i.e. TMP- SMX Topical 5% Imiquimod, used to treat actinic keratoses Activate tumour-necrosis-factor- alpha, an inflammatory cytokine Skin Epidermal layer Dermal-Epidermal Junction Dermal layer Triggering agent (infection, drugs) Immune-mediated inflammation and epidermal tissue damage Erythema multiforme Inflammation ↑ capillary blood flow in dermis Red colouring of skin in the area Centre of lesions contain a necrotic core Inflammatory edema causes margins around necrosis to form a raised and pale ring Inflammation stimulates cutaneous itch receptors Erythematous, papular, target-shaped, pruritic lesions on mucosal and acral (palms of hands, soles of feet) sites and face Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 29, 2022 on www.thecalgaryguide.com

rheumatoid-pneumoconiosis-caplans-syndrome-pathogenesis-and-clinical-findings

Rheumatoid Pneumoconiosis (Caplan’s Syndrome): Pathogenesis and clinical findings Authors: Christopher Li Keerthana Pasumarthi Reviewers: Daniela Urrego, Ben Campbell, Liam Martin* * MD at time of publication Dust-exposed occupation (e.g. coal, asbestos, silica) ↑ Accumulation of dust particles in lungs Dust (e.g. silica) mobilizes from the lungs to other organs such as the kidneys, lymph nodes, and spleen Accumulation of silica in other organs which activate the immune system to secrete cytokines, chemokines, and lysosomal enzymes Activation of antigen- presenting and antibody- producing cells Increased risk to produce autoantibodies Increased risk for autoimmune conditions such as rheumatoid arthritis See slide: Rheumatoid Arthritis (RA): Extra- articular manifestations for mechanism of systemic inflammation See slide Pneumoconioses: Pathogenesis and clinical findings for mechanism Note: Rheumatoid arthritis may precede lung nodules or develop later in the course Rheumatoid arthritis Systemic autoimmune inflammatory disease that mainly involves synovial joints (+) Alveolar macrophages and neutrophils ingest dust particles ↑ Inflammation and cytokine production in pulmonary parenchyma (e.g. interleukin-1, tumor necrosis factor-α) Rheumatoid pneumoconiosis Interstitial lung disease, with characteristic nodules, resulting from the interaction between dust inhalation and rheumatoid arthritis inflammation Cytokines recruit histiocytes, neutrophils, lymphocytes, and fibroblasts to the area to produce a zone of inflammation around the dust-containing cell Necrosis and apoptosis of dust-containing cells, macrophages, and surrounding collagen Necrotic cells are digested by new macrophages to restart the process Production of nodules that contain a central necrotic area surrounded by alternate layers of dust and necrotic tissue (Caplan nodules) Hyperactive immune response to foreign materials in lungs Multiple concentric rings of dust seen histologically on light microscopy 0.5-5 cm rounded opacities on chest X-ray in periphery of lungs See slide on Pneumoconioses for symptoms and pulmonary function test results Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 17, 2022 on www.thecalgaryguide.com

Acute Liver Failure: Pathogenesis and clinical findings

Acute Liver Failure: Pathogenesis and clinical findings Authors: Juliette Hall Reviewers: Vina Fan, Ben Campbell, Mayur Brahmania* * MD at time of publication Acetaminophen Overdose Accumulation of toxic NAPQI (a metabolite of acetaminophen) NAPQI binds hepatocellular proteins (see Acetaminophen Overdose: pathogenesis and clinical findings slide) Drug-induced liver injury Metabolism of drugs by the liver can produce reactive drug metabolites Intracellular stress, mitochondrial injury, or immune response Viral Hepatitis (i.e. HAV, HBV, HEV, HSV) Acute infection or infection flare provokes an immune response against infected hepatocytes Autoimmune Hepatitis Autoimmune antibodies attack hepatocytes (see Auto-immune Hepatitis (AIH) slide) Ischemia (i.e. from shock) ↓ O2 delivery to the liver Hepatocellular hypoxia Wilson’s Disease Heritable mutation in the ATP7B gene ↓ Biliary excretion of copper Hepatic copper accumulation injures hepatocytes (see Wilson’s Disease slide) Accelerated rate of hepatocellular necrosis or apoptosis Hepatocyte death exceeds regeneration such that liver function is compromised within a short amount of time Acute Liver Failure An illness of <26 weeks duration in the absence of pre-existing cirrhosis, characterized by INR ≥1.5 and evidence of altered mentation (hepatic encephalopathy) Injured hepatocytes leak hepatic enzymes (AST, ALT, GGT) into circulation ↑ Liver enzymes Hepatocellular inflammation Stimulation of foregut autonomic nerves Right upper quadrant pain ↓ Toxin metabolism Toxins build up and activate microglial cells (brain macrophage) Oxidative stress and cerebral edema Hepatic encephalopathy Characteristic set of neuropsychiatric symptoms (see Hepatic Encephalopathy slide) ↓ Hepatocellular function and number ↓ Complement protein synthesis ↓ Ability to clear immune complexes and activate B cells Accumulation of pigmented bilirubin ↓ Synthesis of coagulation factors ↑ INR ↓ Conjugation of bilirubin by the liver and ↓ transport into bile for excretion ↑ Serum bilirubin Jaundice Infection Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 15, 2022 on www.thecalgaryguide.com

Acute and Chronic Gastritis: Pathogenesis and clinical findings

Acute and Chronic Gastritis: Pathogenesis and clinical findings Author: Oswald Chen Reviewers: Vina Fan, Ben Campbell, Eldon Shaffer* * MD at time of publication Infectious Helicobacter pylori (most common) Noninfectious NSAIDs, alcohol, gastric reflux Stress Critical illness, trauma Gastric ulceration (see Peptic Ulcer Disease slide) ↓ Gastric mucosal defense (↓ secretion of prostaglandins and mucus) Acid erodes gastric mucosa Inflammatory cells (primarily neutrophils) infiltrate site of injury Acute Gastritis Acute inflammation of gastric mucosa Inflammatory cells (primarily lymphocytes and plasma cells) accumulate in gastric mucosa Autoimmune Metaplastic Environmental Metaplastic Atrophic Gastritis (AMAG) Atrophic Gastritis (EMAG) Atrophic Gastritis Chronic inflammation of gastric mucosa Inflammatory cells destroy gastric glandular epithelial cells Gastric mucosal atrophy and metaplasia (replacement of gastric mucosal cells with intestinal epithelial cells, commonly goblet cells) Hypochlorhydria (parietal cell loss → ↓ hydrochloric acid secretion) ↓ Iron absorption Iron deficiency anemia (see Iron Deficiency Anemia slide) Activation of chemoreceptors and mechanoreceptors Activation of visceral nociceptors Visceral afferents stimulate chemoreceptor trigger zone of medulla Nausea/ vomiting Autoimmune Associated with human leukocyte antigens HLA-B8 and HLA-DR3, which are proteins expressed on immune cell surface Antibodies destroy parietal cells and intrinsic factor in gastric body and fundus Epigastric pain (typically burning or gnawing) Dyspepsia (abdominal discomfort after eating, often with early satiety and bloating) Parietal cell loss → ↓ intrinsic factor → ↓ vitamin B12 absorption Vitamin B12 deficiency (see Vitamin B12 Deficiency slide) Macrocytic Peripheral anemia neuropathy ↓ Gastric acidity leads to ↓ inhibition of G cells in antrum Hypergastrinemia (↑ gastrin release from G cells) Gastrin binds to cholecystokinin-B (CCK-B) receptors on parietal and enterochromaffin-like (ECL) cells of gastric body ↑ CCK-B signaling leads to ↑ cell proliferation and ↓ cell death (↓ apoptotic activity) Hyperplasia (↑ number of cells) Low-grade dysplasia (disordered growth of epithelium) High-grade dysplasia Carcinoid tumor (0.7% of cases) Malignancy arising from ECL cells Gastric adenocarcinoma (0.3% of cases) Malignancy arising from gastric epithelial cells Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 15, 2022 on www.thecalgaryguide.com

Achalasia: Findings on Fluoroscopy with Barium Swallow

Achalasia: Findings on Fluoroscopy with Barium Swallow Authors: Nameerah Wajahat, Omer Mansoor, Aly Valji Reviewers: Tara Shannon, Reshma Sirajee, Stephanie Nguyen* *MD at time of publication Barium swallow performed (patient swallows barium contrast, a radiopaque agent, which outlines the gastro-intestinal (GI) tract during fluoroscopy) Primary Achalasia (idiopathic) Secondary (Pseudo) Achalasia (due to another disease process such as tumor, Chaga’s disease, diabetes mellitus) Achalasia Secondary disease processes can cause denervation or nerve dysfunction of esophageal myenteric plexus (EMP). Tumors can obstruct the lumen and infiltrate the EMP. Visual differences from primary achalasia Look for fixed abnormalities and/or mucosal irregularities and shouldering in the setting of a tumor Nerves controlling the lower esophagus are damaged, making it difficult for food and liquids to pass the esophagus See “Achalasia: Pathogenesis and Clinical Findings” for full pathogenesis of primary and secondary achalasia Inflammation and degeneration of nerves in the wall of esophagus Dysfunction of the esophageal myenteric plexus (network of nerves in the GI tract responsible for peristalsis and sphincter relaxation) Incomplete relaxation of the Loss of peristalsis in distal lower esophageal sphincter (LES) esophagus Barium has difficulty passing through the LES to the stomach Barium outlines the GI tract, following esophageal abnormalities Normal findings Esophageal Dilatation Occurs upstream of narrow LES Bird Beak Sign / Rat Tail Sign Smooth narrowing of the distal esophagus Incomplete LES relaxation Barium Swallow may be normal in some patients with achalasia. Esophageal manometry (gold standard for diagnosis) or upper endoscopy can be considered instead. Image Source: Radiopaedia Legend: Pathophysiology Mechanism Radiographic Findings Complications Published November 9, 2022 on www.thecalgaryguide.com

popliteal-bakers-cyst-pathogenesis-and-clinical-findings

Popliteal (Baker’s) Cyst: Pathogenesis and clinical findings Authors: Liam Thompson, Megan Ure Reviewers: M. Patrick Pankow, Tara Shannon, Reza Ojaghi, Usama Malik, Dr. Gerhard Kiefer* * MD at time of publication Repeated contraction of muscles surrounding the bursaàmicro trauma to bursa Inflammatory response Idiopathic (common: kids 4-7 years old) Bursa located between medial head of gastrocnemius and semimembranosus tendon Accumulation of inflammatory fluid into the bursa forming a cyst Meniscal Tear Tear creates a channel between joint capsule and bursa posterior to the knee joint Rheumatoid Arthritis Auto-immune mediated inflammation of knee joint Osteoarthritis Destruction of articular cartilageà inflammation within knee joint See Osteoarthritis: Pathogenesis slide Damage to joint capsule and accumulation of inflammatory fluid Proteolytic enzyme dysregulation Local muscle action influences fluid flow and pressure changes Extra- articular Popliteal Cyst Fluid filled sac behind knee Usually asymptomatic (resolves spontaneously) Synovial joint herniates into popliteal fossa (most commonly medially)àaccumulation of fluid (synovial + inflammatory) into synovial herniation, forming a cyst Knee flexion Intra-articular Popliteal Cyst Known as “Baker’s cyst” Knee extension ↑ Muscle tension around cyst Channel between knee joint and cyst gradually closes with ↑ tensionàat full extension, no fluid flow between the joint and cyst (trapping the fluid in the cyst) ↓ Muscle tension around cyst Channel between knee joint and cyst opens Knee joint pressure becomes negative ↑ Fluid flow from cyst into knee joint ↓ Fluid in popliteal cyst Knee joint pressure becomes positiveà ↑ Fluid flow from knee joint into cyst (Posterior tibial nerve located lateral to the popliteal cyst and enervates posterior knee, calf, and bottom of foot) Posterior tibial nerve becomes entrapped by mass (cyst) Enlarging mass in posterior knee Cyst reaches maximum volume Pressure within cyst exceeds tensile strength of surrounding sac Fluid drains distally into calf Popliteal vein located lateral to cyst ↑ Venous pressure distal to cyst Popliteal vein occluded by mass Venous pooling distal to site of occlusion ↓ Space in posterior calf compartmentàcompression of calf muscles and posterior tibial nerve Ankle dorsiflexion ↑ pressure in compartment Positive Homan’s sign (discomfort with passive ankle dorsiflexion) Posterior plantar numbness Pain receptors (nociceptors) activated Posterior knee pain/pressure Cyst Rupture Abrupt and intense pain Stimulates inflammatory response Fluid pushed from veins into interstitial space Swelling and erythema (redness) in distal calf and foot Pseudo-Thrombophlebitis worse with extension or physical activity (shares symptoms with deep vein thrombosis but no associated clot) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Feb 10, 2018, updated Nov 19, 2022 on www.thecalgaryguide.com

hypovolemic-shock

Hypovolemic Shock: Pathogenesis, Complications, and Clinical Findings Authors: Dean Percy Miranda Schmidt Reviewers: Yan Yu Tristan Jones Frank Spence* Ben Campbell Ayaaz Sachedina* * MD at time of publication Progressive ↓ in level of consciousness Pulseless Electrical Activity Acute Kidney Injury ↑ Reabsorption of salt and water in the kidney Oliguria (↓ urine output) Inflammation (pancreatitis, cirrhosis, post-operative, etc.) Inflammatory mediators ­ vessel permeability and fluid leaks out Trauma Ruptured vessels leak fluid into potential spaces Hemorrhagic losses (GI bleed, postpartum hemorrhage, etc.) ↓ Intravascular volume ↓ Venous return to the heart ↓ Cardiac output (blood pumped from the heart) Hypovolemic Shock ↓ Oxygen delivery to tissues due to low blood volume Insufficient organ perfusion Non-Hemorrhagic losses (dehydration, GI losses, skin losses / burns, renal losses, etc.) ‘Third Spacing’ of fluid (fluid located outside the intravascular or intracellular space; large collections can occur in the pelvis, thorax, GI tract, long bones of children, intra-abdominally, retroperitoneally) P = Q x R; less ‘flow’ in the vessels (Q), with vessels not constricting enough to maintain resistance (R)à pressure (P) will drop ↓ Blood Pressure Caution: young, healthy individuals can maintain blood pressure during circulatory collapse with ­ cardiac output and ­ vasoconstriction; do not use blood pressure as an indicator of shock severity in children Carotid sinus baroreceptors sense low blood pressure ↓ Carotid sinus inhibition of sympathetic nervous system Release of sympathetic catecholamines (epinephrine and ↓ Pressure in venous circulation Brain Heart Kidneys ↓ Blood in the right internal jugular vein ↓ Oxygen delivery to the brain ↓ Myocardial contractility (from lactic acidosis) ↓ Blood flow to kidneys ↓ Jugular Venous Pressure Catecholamines bind to beta-1 receptors in the sinoatrial node of the heart Beta-1 receptor activation causes ↑ heart rate Tachycardia norepinephrine) Catecholamines bind to and stimulate alpha-1 receptors in peripheral vessels Vasoconstriction of peripheral vessels ↓ Blood flow to peripheral tissue Catecholamines bind to and stimulate beta receptors in sweat glands Diaphoresis (sweating) In all body tissues Inadequate oxygen delivery ↓ ATP production ↑ Anaerobic metabolism ↓ Body temperature Impaired neurological functioning Renal ischemia Activation of the renin-angiotensin aldosterone system ↓ Glomerular filtration rate ↓ Clearance of lactic acid by the kidney ↑ Lactic acid production ↓ Rate of activity of clotting enzymes Lactic Acidosis Unknown mechanism Coagulopathy Hypothermia Trauma Triad of Death ↑ Capillary Cold, mottled refill time extremities Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 24, 2013, updated December 4, 2022 on www.thecalgaryguide.com

Ischemic Stroke: Pathogenesis

Ischemic Stroke: Pathogenesis Small artery occlusion Acute injury (<20mm diameter) of basal or brainstem penetrating arteries Large artery atherosclerosis Cholesterol plaque ↓ diameter of intra- or extracranial vessel Cardiac embolism Blood clot in heart breaks free, travels to brain Other E.g. volume loss, severe infection Unknown E.g. 2 or more mechanisms Modest ↓ in O2 at penumbra (see figure) Authors: Mizuki Lopez Andrea Kuczynski Illustrator: Mizuki Lopez Reviewers: Sina Marzoughi Usama Malik Hannah Mathew Ran (Marissa) Zhang Andrew M Demchuk* Gary M. Klein* * MD at time of publication Significant ↓ in O2 at ischemic core (see figure) ↑ Anaerobic metabolism ↓ ATP Production Dysfunction of Na+/K+ ATPase pump (for 1 ATP molecule, 3 Na+ moved out of cell, 2 K+ moved into cell) H2O influx following Na+ Cerebral edema Compression of vessels and surrounding tissue damages blood-brain barrier ↑ Permeability of damaged blood-brain barrier Infiltration by peripheral immune cells Immune cells release inflammatory cytokines ↓ Cerebral Blood Flow Penumbra Ischemic core Metabolic demands are greater than supply of ATP Cell death Microglia (resident neural immune cells) activate to clean dead cell debris Microglia release inflammatory cytokines (TNFα, IFγ, IL-1β) Cytokines lead to astrocyte activation (support cells for neurons) Astrocytes release more inflammatory cytokines Inflammation of brain tissue ↑ Na+, Ca2+ influx, K+ outflux ↓ Glutamate (excitatory neurotransmitter) reuptake by astrocytes (support cells for neurons) ↑ Glutamate in extracellular fluid Spreading depolarization from core (unclear mechanism) Activate biochemical pathways including glutamate receptor activation ↑ Glutamate activity Activate glutamate receptors that conduct Ca2+ ↑ Ca2+ influx into neuron Activation of catabolic proteases, lipases, nucleases in neuron Dysfunction of neuronal protein synthesis and activity Neuronal cell death ↑ Volume of dead (infarcted) brain tissue Neurons depolarize and release glutamate Reversal of Na+ Dependent Glutamate Reuptake Transporters on astrocytes (normally 3 Na++ 1 H+ + 1 glutamate into cell, for 2 K+ out) ↑ Glutamate in extracellular fluid Stroke symptoms (e.g. weakness, slurred speech, visual field losses, autonomic dysfunction) (see Ischemic Stroke: Impairment by Localization stroke slide) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 14, 2017; updated November 6, 2022 on www.thecalgaryguide.com

Cirrhosis

Cirrhosis: pathogenesis and complications Author: Chunpeng Nie Yan Yu Reviewers: Paul Ratti, Amy Maghera, Vina Fan, Ben Campbell, Sam Lee*, Mayur Brahmania* *MD at time of publication Chronic viral hepatitis (B, C, or D) Hepatitis D occurs with hepatitis B Alcohol related liver disease Non-alcoholic steatohepatitis Autoimmune: autoimmune hepatitis, primary biliary & sclerosing cholangitis Genetic: hemochromatosis, Wilson’s disease, α1- antitrypsin deficiency Toxic: drugs may rarely cause chronic liver disease or cirrhosis Severe or chronic hepatocyte injury overrides regenerative capacity → Fibrosis Cirrhosis Mild fibrosis may reverse with treatment of underlying cause Nodular/shrunken liver on ultrasound ↑ Liver stiffness on transient elastography Diffuse fibrosis with nodular regeneration on biopsy Fibrotic liver provides ↑ resistance to blood flow Portal hypertension Irreversible formation of fibrosis, within which hepatic cell regeneration is restricted to form nodules of poorly-functioning cells Inflammation → epigenetic changes, oncogene mutations Hepatocellular carcinoma ↑ Serum α-fetoprotein (sensitivity 50%, specificity 99%) Fibrosis disrupts normal function of hepatic lobules Hepatic insufficiency ↓ Liver synthetic function ↓ Thrombopoietin synthesis Thrombocytopenia ↓ Conjugation of bilirubin, ↓ secretion of bilirubin into bile ducts, and ↓ drainage of bilirubin into hepatic duct Accumulation of serum bilirubin >30 μmol/L Jaundice Scleral icterus, jaundiced frenulum ↑ Pressure in portal venous circulation Portosystemic shunts Increased flow to esophageal, rectal, and splenic veins Vascular stretch → endothelial vasodilator (e.g. NO) release Vasodilators enter systemic circulation Pulmonary vasodilation Blood cells in pulmonary vasculature have ↓ time for gas exchange Hepatopulmonary syndrome (rare) Dyspnea or hypoxemia, worsened when upright ↓ Synthesis of clotting factors (V, VII, IX, X, XI, XII, fibrinogen, prothrombin) and anticoagulant proteins (antithrombin, proteins C/S) Unpredictable imbalance of hemostatic and anticoagulant factors Elevated INR ± coagulopathy Impaired metabolism of waste products and toxins Toxins (mainly ammonia) accumulate and cross the blood- brain barrier Hepatic encephalopathy Day-night reversal, asterixis, delirium Varices (dilated veins in the esophagus, stomach, or rectum) Variceal bleed GI bleed and hypovolemia Backflow of blood into spleen Splenomegaly Enlarged spleen sequesters (traps) blood cells Cytopenias (eg. thrombocytopenia or anemia), petechiae, easy bruising ↓ Blood flow to kidneys, which sense ↓ effective blood volume Kidneys retain water and Na+ ↑ Hydrostatic pressure in splanchnic vessels ↓ Albumin synthesis ↓ Capillary oncotic pressure Net fluid flux out of vasculature into interstitial space Ascites (fluid in peritoneal cavity) Peripheral edema Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published August 7, 2022, updated November 6, 2022 on www.thecalgaryguide.com

Hidradenitis Suppurativa

Genetic mutations causing impaired function of gamma-secretase (NCSTN, PSEN1 or PSENEN genes) Defective notch signaling pathway (a regulator of many cell processes) Hormones (excess androgen activity) Smoking (nicotine exposure) Skin to skin friction Systemic inflammation Hidradenitis Suppurativa: Pathogenesis and Clinical Findings Other unknown genetic factors Follicular occlusion HS nodule Epidermal layer Dermal- Epidermal Junction Dermal layer Inflammatory cytokine- mediated activation of nociceptors Inflammatory cytokines Sebaceous gland Apocrine sweat gland Hair follicle Pilosebaceous- apocrine unit Changes in gene expression of hair follicle and apocrine gland anti-microbial peptides Accumulation of corneocytes (dead keratinocytes) and sebum àfollicular occlusion and rupture ↑ Interleukin-36 (IL-36, a cytokine) Altered keratinocyte differentiation Hair follicle hyperkeratinization Abnormal structure and function of the pilosebaceous- apocrine unit Infiltration of normal skin flora microbes, macrophages, dendritic cells, and Th17 cells Increased density of nicotinic acetylcholine receptors in pilosebaceous-apocrine unit (see figure) Mechanism not fully understood Hyperhidrosis Pain Innate immune cells produce inflammatory cytokines: tumour necrosis factor alpha (TNF-α) and various interleukins (IL-1, IL-6, IL-12, IL-17, IL-22 and IL-23) IL-17 promotes neutrophil migration into the skin Formation of neutrophil extracellular traps (NETs) B-cell activation and IgG autoantibody formation against skin tissue antigens Scarring Ongoing inflammation impairs wound healing Granulocyte infiltration and activation, release of granulocyte colony-stimulating factor Accumulation of keratin, purulent and/or serosanguinous fluid in dermis Inflammatory papules, nodules, and abscesses Pro-inflammatory cytokine-mediated response, leading to epithelial hyperplasia with increased fibrosis and collagen remodelling in the dermis Formation of epithelial tissue tunnels in the dermis with two cavities on either end that open to the skin surface and fill with fluid or keratin Hidradenitis Suppurativa Chronic Inflammatory skin disease that occurs in areas with a high density of apocrine sweat glands, including the axilla, underneath the breasts, groin, and buttocks Sinus tracts (dermal connections between lesions) Double-ended comedones Authors: Leah Johnston Reviewers: Mehul Gupta Lauren Lee Stephen Williams Ben Campbell Laurie Parsons* * MD at time of publication Wound drainage and odour Psychological distress Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 30, 2023 on www.thecalgaryguide.com

Inhalational Injury

Inhalation Injury: Pathogenesis and complications Authors: Marshall Thibedeau, W Fraser Hill, Paloma Arteaga Juarez Reviewers: Spencer Yakaback, Tony Gu, Dami Omotajo, Ben Campbell, Yan Yu*, Michael Liss*, Duncan Nickerson*, Donald McPhalen* * MD at time of publication Smoke Inhalation Suspect if patient found unconscious, history of fire in a confined space and presence of facial burns Convective heat transfer Exposure to chemical irritants Tracheobronchial injury Injury stimulates vasomotor and sensory nerves of the trachea and bronchi Neuropeptides from neurons are released into local circulation and activate nitric oxide Inhalation of toxins Lack of O2 in an enclosed space Asphyxiation (O2 deprivation in lungs) Acute hypoxemia Loss of consciousness Death Upper airway injury (above vocal cords) Cell lysis & necrosis Local release of inflammatory substances ↑ Vascular permeability à edema of tissues in upper airway Damage to lower respiratory tract cilia ↓ Mucus clearance from alveoli Parenchymal injury (delayed reaction dependent on severity of burn) Alveolar epithelial and endothelial barrier irritation/damage Inflammatory response Carbon monoxide poisoning Cyanide poisoning Cyanide binds to mitochondrial cytochrome oxidase a3 CO binds more strongly to hemoglobin than O2 ↑ Carboxyhemoglobin in blood, ↓ free hemoglobin available to bind O2 in the lungs ↑ Affinity for O2 on remaining binding sites in hemoglobin (i.e. hemoglobin binds O2 more strongly and is slow to release it) ↓ O2 delivered to tissues Inhibition of cytochrome c oxidase Mucous obstructs airways Air retained distal to the obstruction is resorbed from nonventilated alveoli Regions without gas collapse i.e atelectasis ↑ Risk of infection ↓ Mitochondrial respiratory chain function Impaired oxidative phosphorylation & cellular energy production Cellular dysfunction in high metabolic tissues Nitric oxide acts as a vasodilator in alveolar arterioles Loss of hypoxic vasoconstriction (constriction of arterioles in alveoli due to ↓ O2) Reactive inflammation & bronchoconstriction Stridor Complete airway obstruction ↑ Vascular permeability leading to fluid leakage into interstitium and alveoli Blood flow to poorly ventilated alveoli is maintained Ventilation/perfusion (V/Q) mismatch (regions of lung not effectively ventilated despite being well perfused by blood) Acute Respiratory Distress Syndrome See ARDS Pathogenesis slide Hypoxemia Lower airway edema Wheezing Coughing Impaired brain function Muscle weakness Impaired heart function Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications First published November 10, 2019; Updated on February 12, 2023 on www.thecalgaryguide.com

Central Retinal Vein Occlusion

Central Retinal Vein Occlusion: Pathogenesis and clinical findings Authors: Graeme Prosperi-Porta Mina Mina Reviewers: Stephanie Cote Usama Malik Mao Ding Johnathan Wong* *MD at time of publication Hypercoagulable state (pathologic state where there is an exaggerated tendency for the blood to clot) ↓ Anticoagulation (e.g., Protein C or S def) and/or ↑ coagulation (e.g., malignancy, Polycythemia Vera) Non-ischemic (perfused) CRVO Glaucoma (a disease characterized by ↑ intraocular pressure) Optic disc drusen (calcified nodules located within the optic disk – the most anterior part of the optic nerve) Diabetes Dyslipidemia Hypertension Vasculitis (inflammation of blood vessels; e.g., sarcoid, Systemic Lupus Erythematosus) Endothelial damage Pupillary responses do not vary between both eyes when a light is shone in one eye at a time Relative afferent pupillary defect (RAPD) mild or absent Lost vascular wall integrity Normal retinal electrical response to a light stimuli Normal electro- retinography (ERG) with b- wave >60% Few scattered Intra-retinal hemorrhages ↓ In retinal electrical response to a light stimuli Pupils respond differently to a light stimulus shone in one eye at a time Severe ↓ in visual acuity (Snellen acuity of <20/400) Visual field deficits ↓ b-wave amplitude (<60%) on ERG RAPD present ↑ Pressure compromises retinal vein outflow Central retinal atherosclerosis (build-up of fat & cholesterol plaque in arteries) & hardening Atherosclerotic changes in the central retinal artery compress the central retinal vein (since they are both held together in region of the optic disc) Venous stasis (stagnation of blood flow) ↑ Likelihood of thrombus formation Central Retinal Vein Occlusion (CRVO) A common retinal vascular disease characterized by blockage of the main vein that drains blood from the retina CRVO classified based on the degree of perfusion (as seen through retinal angiography) Ischemic (nonperfused) CRVO ↑ Intraluminal venous pressure Dilated tortuous retinal veins Normal visual fields Vascular wall integrity lost Four-quadrant hemorrhages described as “blood and thunder” on fundus exam Obstruction due to thrombus ↓ Retinal capillary perfusion causes ischemia Hypoxia in the retinal tissues ↑ Release of vascular endothelial growth factor to revascularize diseased tissue & overcome hypoxic conditions Angiogenesis (formation of new blood vessels) Intraretinal infarcts “Cotton wool spots” on fundus exam Venous capillary fluid/protein leakage Mild retina, macula and disc edema Moderate ↓in visual acuity often (Snellen acuity >20/400) New vessel proliferation can occur in the anterior chamber of the eye This change can block the outflow path of the aqueous humor in the eye Neovascular glaucoma Neovascular vessels are structurally different in comparison to regular retinal vasculature Neovascular vessels are more fragile ↑ Likelihood of rupture Vitreous hemorrhage Neovascular vessels lack tight junctions ↑ Fluid leakage Retina, macula and disc edema Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications First Published June 28, 2017, updated March 4, 2023 on www.thecalgaryguide.com

Douleur somatique aigue

Douleur somatique aigue: Auteurs: Lisa Murphy, Yan Yu* Rédacteurs: Mackenzie Gault, Melinda Davis* Traducteur/Traductrice: Ovidiu Croitoru Sylvain Coderre* * MD au moment de la publication Nocicepteurs: Neurones qui détectent les stimulis nocifs ou douloureux et transmettent ces informations à la moelle épinière. Il existe deux grands types: - A∂ fibres: Myélinisés, sensation initiale nette et rapide. - C fibres: amyélinisés, sensation retardée, terne, brûlante. Vers l’hypothalamus Les neurones de 2e ordre synapsent dans l’hypothalamus Les neurones hypothalamiques coordonnent la réponse viscérale du corps à la douleur Pathophysiologie Lésions tissulaires aigues, trois types de causes: Mécanique (ex: piqure) Thermique (ex: poêle chaude activé) Chimique (ex: inflammation) Nocicepteurs activités au site de blessure (Neurones sensoriels de 1er ordre) Fibres nociceptives (A∂ et C) transportent l’information sensorielle nocive vers la corne dorsale ipsilatérale de la moelle épinière Les neurotransmetteurs excitateurs sont libérés et stimulent les neurones sensoriels de 2ème ordre. Les neurones sensoriels de 2ème ordre décussent immédiatement dans la moelle épinière et remontent via les voies antérolatérales (spinothalamiques) du côté opposé, se terminant à divers endroits Vers le thalamus Les neurones de 2e ordre synapsent dans le thalamus Dans le thalamus, les neurones sensoriels de 2ème ordre synapsent avec les neurones sensoriels de 3e ordre, qui transmettent le signal au cortex cérébral Vers le tronc cérébral Les neurones de 2e ordre synapsent dans la formation réticulaire du tronc cérébral Vers le mésencéphale Les neurones de 2e ordre synapsent dans la zone grise périaqueducale (PGA) du mésencéphale Localisation et sensation douleur Réponse émotionnelle et comportementale Stimule les voies descendantes pour moduler le signal de douleur Diminution ou augmentation de la perception de la douleur ↑ Rythme cardiaque Nausée Légende: Pathophysiologie Mécanisme Signes/Symptôme/Labo Complications Publié 25 avril 2019 sur www.thecalgaryguide.com

Pyogenic Brain Abscess on MRI

Pyogenic Brain Abscess on MRI: Findings and Pathogenesis Common pathogens such as staphylococcus and streptococcus bacteria exist in the outside environment or on the skin Hematogenous Spread Direct Spread Pathogen travels to brain by bloodstream Pathogen travels to brain by ears or sinus Pathogen enters the brain parenchyma by crossing the blood brain barrier (BBB) transcellularly, paracellularly or by a Trojan Horse mechanism Authors: Omer Mansoor, Aly Valji, Nameerah Wajahat Reviewers: Mao Ding, Reshma Sirajee, James Scott* *MD at time of publication R Transcellular Pathogen invades BBB cell directly to enter Paracellular Pathogen goes between BBB cells by disrupting tight junctions Trojan Horse Pathogen bypasses BBB by hiding inside a macrophage cell Ring Enhancing Lesion Sensitive, but not specific for a Brain Abscess Pathogen causes parenchymal inflammation and progresses through four stages of infection Axial T1 + Gadolinium MRI Head. Pyogenic Brain Abscess showing infection at Stage 3 or 4. T1 highlights fat, whereas T2 highlights fat and water*. R Stage 1: Early Cerebritis Focal infection (2-3 days) with no pus formation Stage 2: Late Cerebritis Progressive (1 week) infection of abscess Stage 3: Early Encapsulation In 1-2 weeks, pus is formed from the pathogen Stage 4: Late Encapsulation After 2 weeks, abscess shrinks in size as it necroses Pathogen causes acute inflammatory changes of swelling (edema) and vascular congestion No fibrous capsule is formed yet and infection is not well localized on a T1 MRI Increased edema could be seen on T2 MRI Poor Demarcation and Vasogenic Edema Abscess is not well-defined with minimal enhancement on T1 but can have increased signal on T2 Fibrous capsule is formed by surrounding healthy brain tissue that walls off abscess Capsule is made of granulation tissue and fat, which lights up non-specifically on a T1 MRI Use Diffusion Weighted Imaging (DWI) to distinguish abscess from other brain lesions DWI measures water diffusion in different directions, specifically diseased areas where water movement is restricted Restricted Diffusion Edema and inflammation allow water to move freely (hyperintense signal) *Imaging Source: Feraco et al., 2020: https://jptcp.com/index.php/jptcp/article/download/688/685?inline=1 DWI Sequence Axial MRI Head. Same Pyogenic Brain Abscess as above. DWI is the mainstay imaging sequence for diagnosing a pyogenic brain abscess*. Legend: Pathophysiology Mechanism Radiographic Findings Complications Published Mar 25, 2023 on www.thecalgaryguide.com

Carpal Tunnel Syndrome

Carpal Tunnel Syndrome: Pathogenesis and clinical findings Diabetes Mellitus (See Pathogenesis Slide) ↑ Blood sugar: deposition of advanced glycation end (AGE) products (proteins or lipids glycated when exposed to sugar) AGE attaches to and prevents tendons from moving properly Authors: Amanda Eslinger Yvette Ysabel Yao Reviewers: Matthew Harding Owen Stechishin Mao Ding, Cory Toth* * MD at time of publication Wrist trauma (distal radius fractures, carpal/metacarpal fractures, tendon ruptures) Repetitive Strain Injury (repetitive hand & wrist movements) Irritation, swelling & thickening of tendons in carpal tunnel Calcium deposits Calcifica tion Deposition Amyloidosis Amyloid (protein aggregates) deposition Gout (See Gout Slide) Uric acid crystal deposition Pregnancy ↑ Concentration of hormones & uterine pressure on inferior vena cava Backup of blood into systemic circulation Autoimmune (i.e. Rheumatoid arthritis, scleroderma, lupus, Sjogren’s syndrome) ↑ Inflammatory cytokines causing inflammation Hypo- thyroidism Myxedema (swelling of skin and underlying tissues) in carpal tunnel Idiopathic or Congenital Edema Narrowed carpal tunnel leads to ↑ internal pressure Carpal Tunnel Syndrome Vascular: median artery thrombosis in carpal tunnel Median nerve compression inside the carpal tunnel Mechanical disruption of median nerve Compression exacerbated with flexed wrists (i.e. sleep, driving, holding phone/cup) Disruption of daily activities and sleep Ischemia (↓ blood supply) to median nerve Hypoxia (↓ oxygenated blood flow) Metabolic conduction block (impaired axonal transport due to ischemia) Nerve conduction study (show sensory nerve impulses slowing across the wrist, followed by mild / moderate / severe loss of sensory nerve amplitude Damage to the myelin sheath ↓ Saltatory conduction (action potential propagation along myelinated axons) Neuropraxia (nerve compression blocks conduction) Interruption in axonal continuity Axonotmesis (endoneural tube stays intact but myelin & distal axon degenerates) Recovery possible Full disruption of myelin, axon & nerve sheath Neurotmesis (axons no longer have an endoneural tube to guide regrowth) Recovery impossible ↓ Ability to contract and use abductor pollicis brevis muscle ↓ Signals through median nerve Interference with signals to the brain causes unusual sensations Hypoalgesia (↓ pain Dysesthesia (tingling, burning, or sensitivity at 1st 3 1⁄2 digits) painful sensation at 1st 3 1⁄2 digits) Thenar muscle wasting Reduced hand dexterity Weak thumb abduction Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published December 2nd, 2013, updated March 22, 2023 on www.thecalgaryguide.com

Acute Pulmonary Embolism on CTPA

Acute Pulmonary Embolism: Computed Tomography Pulmonary Angiogram (CTPA/CTPE) Virchow’s Triad: Hypercoagulability, venous stasis, vascular endothelial injury Image Source: European Society of Radiology Image: Polo mint sign on axial CTPA. Image Source: Journal of The Indian Academy of Echocardiography Image: Railway sign on axial CTPA. Image Source: Moore et al. 2018 Image: Pleural effusion and pulmonary infarction on axial CTPA. Authors: Aly Valji, Nameerah Wajahat, Omer Mansoor Reviewers: Reshma Sirajee, Sravya Kakumanu, Victória Silva, Mao Ding Vincent Dinculescu* *MD at time of publication Deep Vein Thrombosis (DVT): Majority of pulmonary embolism (PE) arise from DVT: Clot travels via inferior vena cava → right atrium → right ventricle → pulmonary arteries/arterioles See “Virchow’s Triad and Deep Vein Thrombosis” for full pathogenesis Polo Mint Sign Clot visualized in short axis, Filling defect entirely surrounded by IV contrast creating a circle (polo mint) Railway Sign Clot visualized in long axis, Filling defect surrounded by IV contrast on two sides creating the appearance of a railway track Type I or II Ventilation/Perfusion respiratory failure (V/Q) mismatch Reverse Halo Sign Pulmonary infarction leads to wedge shaped opacity with a rim of consolidation (black arrows) surrounding “ground glass” (red arrows) Pulmonary Embolism: Clot in pulmonary arteries See “Signs and Symptoms of Pulmonary Embolism” for full presentation Saddle Embolus: Large clot over the pulmonary trunk bifurcation Lobar/Segmental/Subsegmental Embolus: Clot within the pulmonary arteries of the lungs Blockage of pulmonary arteries = ↓ Blood flow, ↑ Right heart pressure ↓ Gas exchange b/w lungs and blood Ischemia of lung tissue → infarction → inflammation of dead tissue ↑ Right heart filling and expansion Left heart filling impaired ↓ Cardiac output due to ↓ Left heart filling “Massive PE” = sustained systemic hypotension or bradycardia (SBP < 90 mmhg, HR < 40 bpm) Saddle Embolus Filling defect due to blockage of bifurcation. IV contrast appears white, and embolus appears grey Pleural Effusion Exudative Pleural Effusion Tissue inflammation → ↑ blood vessel permeability = Leakage of fluid into pleural space Transudative Pleural Effusion ↑ Hydrostatic pressure from right heart congestion = Pushes fluid into pleural space Image Source: Samra et al. 2017 Image: Saddle embolus on axial CTPA. Legend: Pathophysiology Mechanism Radiographic Findings Complications Published March 28, 2023 on www.thecalgaryguide.com

Coronary Artery Bypass Graft CABG Indications

Coronary Artery Bypass Graft (CABG): Indications Author: Breanne Gordulic Reviewers: Miranda Schmidt Ben Campbell Sunawer Aujla Angela Kealey* * MD at time of publication Symptomatic multivessel (≥ 3 vessels) coronary artery disease (MVCAD) or complex MVCAD Acute coronary syndrome (ACS) Left main coronary artery disease Multivessel (≥ 3 vessels) CAD and diabetes Cardiac surgery required for other pathology Multivessel CAD, LV dysfunction and congestive heart failure (CHF) Complex CAD includes stenosed vein grafts, bifurcation lesions, calcified lesions, total occlusions, ostial lesions STEMI initial treatment is PCI/thrombolysis CABG outcomes compared to percutaneous coronary intervention (PCI) in MVCAD include ↑ survival in diabetes, ↑ survival with LV dysfunction, ↓ repeat revascularization, ↓ myocardial infarction, ↓ stroke ↑ Risk of failure in complex CAD with PCI Rapid reperfusion to myocardium most important in STEMI to decrease myocardial damage CABG can be considered for residual stenoses 6-8 weeks later NSTEMI or unstable angina (UA) with MVCAD involving at least three vessels including the proximal left anterior descending (LAD) Left main coronary artery divides into left anterior descending (LAD) and left circumflex (LCx) which supplies 2/3 of myocardium ↑ Survival Myocardial infarction from left main artery occlusion Death Left main stenosis Ventricular dysrhythmias Ongoing ischemia LV dysfunction Hemodynamic instability ↑ risk of PCI CABG has mortality benefit ↓ Number of operations ↑ Risk of cardiovascular disease in diabetes Revascularization indicated along with other cardiac surgery Multivessel CAD with >90% stenosis and CHF LV ejection fraction <35% ↑ Risk of atherosclerosis from hyperglycemia and dyslipidemia CABG bypasses several atherosclerotic plaques in coronary arteries ↑ Durability ↑ Complete perfusion Valve stenosis or regurgitation Septal defect Aortic root or arch pathology Combination procedure Evidence of ischemia at rest Evidence of impaired LV function at rest ↓ All-cause mortality in CABG vs medical management Chronic obstructive pulmonary disease Abbreviations: • ACS- acute coronary syndrome. Acute reduction in blood flow to heart muscle resulting in cell death. • CAD- coronary artery disease. Narrowing or blockage of the coronary arteries by plaque • NSTEMI- myocardial infarction (heart attack) with no ST elevation on electrocardiogram • PCI- percutaneous coronary intervention. A balloon tipped catheter is used to open blocked coronary arteries; a stent may be placed. • STEMI- myocardial infarction with ST segment elevation on electrocardiogram Consider revascularization (restore blood flow to blocked or narrowed blood vessels) of coronary arteries to increase perfusion to myocardium (heart muscle) Coronary artery bypass graft recommended Assess surgical risk and comorbidities with evaluation by heart team that includes both a cardiac surgeon and interventional cardiologist (SYNTAX Trial) Individual management plan for patients with comorbidities that increase mortality Frailty Chronic Renal Failure ↑ Inflammation and deregulated angiogenesis affects all organ systems ↓ Physiologic reserve and ↓ ability to recover from acute stress ↑ Pneumonia ↑ Respiratory and Renal Failure ↑ Stroke ↑ In hospital mortality ↓ Survival two years after surgery Use Society of Thoracic Surgeons Score, EuroSCORE, or SYNTAX II Score to predict patient outcome with anatomy, disease severity, and preoperative characteristics Coronary Artery Bypass Graft Surgery to take healthy blood vessels from the body and connect them proximally and distally to blocked coronary arteries Cardiopulmonary bypass, fluid overload, ↑ renal vasoconstriction and ↓ renal oxygenation from rewarming Kidney injury ↑ End stage kidney disease Blood flow restored to ischemic myocardium ↓ Angina ↑ Quality of life ↑ LV function ↑ Survival Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published April 12, 2023 on www.thecalgaryguide.com

Telogen Effluvium

Authors: Ayaa Alkhaleefa Telogen effluvium (TE): Causes, pathophysiology, and clinical findings Reviewers: Elise Hansen, Sunawer Aujla, Dr. Jori Hardin* *MD at time of publication Telogen effluvium: non-scarring alopecia characterized by diffuse shedding of telogen-phase hair due to a reactive process Hypothyroidism ↓ Thyroid hormones (T3,T4) ↓ Binding of thyroid hormone to receptors in the skin and hair Cell division ceases in keratinocytes The catagen phase of the hair cycle is triggered (involuting phase where hair enters apoptosis) Delayed re-entry of telogen (resting) hair into the anagen (growing) phase Post-partum hair loss (telogen gravidarum) ↑ Circulating placental estrogen Prolonged anagen phase ↑ Hair growth during pregnancy Baby is delivered ↓ Estrogen and other trophic hormones postpartum The increased amount of anagen hairs from pregnancy all enter catagen phase simultaneously Nutritional deficiencies i.e. iron deficiency Critical illness Fever triggers various pro- inflammatory cytokines (tumor necrosis factor, interleukin 1b, interleukin 6, and interferon types 1 and 2) Premature entry into catagen phase (the body induces cell-cycle arrest in all non-essential structures) Hair follicle keratinocytes undergo apoptosis in response to inflammation Ribonucleotide reductase (an enzyme involved in DNA synthesis) cannot utilize iron as a co-factor ↓Iron stores ↓ Expression of iron- dependent genes (CDC2, NDRG1, ALAD, and RRM2) ↓ Expression of matrix genes of a healthy hair follicle (Decorin and DCT) ↓ Production of matrix keratinocytes (cells that form the hair shaft of growing hair) Arrest of matrix proliferation Hair shedding commonly occurs in the bitemporal areas 2-3 months after triggering event Hair shaft Hair follicle Telogen phase Skin Epidermis Dermal- Anagen phase Epidermal Junction Dermis Catagen phase Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published May 10, 2023 on www.thecalgaryguide.com

OA Clinical findings

Osteoarthritis: Pathogenesis and clinical findings Ehlers-Danlos Syndromes (connective tissue disorders, e.g., Familial Hypermobility Syndromes) Damage of normal cartilage under abnormal loading Authors: Sean Spence Modhawi Alqanaie Reviewers: Yan Yu Jennifer Au Mao Ding Gary Morris* * MD at time of publication Single large traumatic event or repeated microtrauma Damage to normal articular cartilage under normal loading (force put on a joint) Genetic anomalies in cartilage production and inborn errors of cartilage metabolism Damage of abnormal cartilage under normal joint loading Destruction/attrition of articular cartilage Osteoarthritis A degenerative joint disease that can affect both load bearing joints (knee, hip) as well as in smaller joints (proximal inter-phalangeal, carpometacarpal joints in hand) Repeated physical joint trauma Aberrant bone deposition secondary to wear on subchondral bone Formation of osteophytes (bony projections) and subchondral sclerosis (bone thickening) Lack of cartilage Direct contact between bony processes with movement of the joint Inflammation alters the chemical milieu of joint tissue Synovial fluid forced into bone Damage to subchondral (under cartilage) blood vessels Subchondral fractures cytokines regulate hyaluronic acid synthase Synovium makes lower molecular weight hyaluronic acids (a potent proinflammatory molecule) ↓ synovial fluid viscosity ↑ risk of infection Increased secretion of proteolytic enzymes ↑ joint fluid production Joint effusion Disruption of normal joint architecture Palpable bony hypertrophy (ex. Bouchard’s nodes (bony bumps on the middle joints of the finger)) Impaction of osteophyte with normal joint structures during movement Physical disability Crepitus (grating sound in a joint) Joint movement with reduced lubrication stimulates joint nociceptors Stimulation of joint nociceptors (sensory receptors that detect damaging stimuli) in subchondral bone Pain with use of joint Pain with motion ↓ Range of motion Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 1, 2012, updated May 18, 2023 on www.thecalgaryguide.com

Acute Laryngitis

Acute Laryngitis: Pathogenesis and clinical findings Infectious Author: Charmaine Szalay-Anderson Reviewers: Shayan Hemmati, Sunawer Aujla, Derrick Randall*, Viral (most common) Malaise Fever Fungal Atopy (asthma, allergy) Non-infectious Gastroesophageal Reflux Trauma or damage to larynx Smoking Yan Yu* * MD at time of publication Environmental Pollution/Inhalants Bacterial (S. pneumoniae, H. influenzae, M. catarrhalis) Systemic immune response Spread of infection to larynx through upper respiratory tract Infection of the vocal folds and surrounding tissue Mechanical (vocal misuse/ trauma) (Area in the neck that contains the structures for voice production, anatomically anterior to the esophagus, inferior to the pharynx and superior to the trachea) Irritation of the vocal folds and surrounding tissue Inflammatory cascade triggered Acute Laryngitis Symptoms for <3 weeks Acute injury to vocal folds Vocal fold lesions (i.e., vocal polyps) Laryngeal inflammation Neutrophils and macrophages release inflammatory cytokines Local laryngeal inflammationà↑ vascular permeability ↑ Secretion of mucous leading to airway congestion Cough reflex initiated to clear airway congestion Cough Edema of vocal folds and surrounding tissue Dysphagia (difficulty swallowing) Dysphonia (difficulty speaking) Odynophagia (painful swallowing) Swelling impairs vocal cord vibration Frank aphonia (loss of voice) Progressive worsening of edema Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published May 24, 2023 on www.thecalgaryguide.com

diverticulosis-vs-diverticulitis-distinguishing-features

Diverticulosis vs. Diverticulitis: Distinguishing features Authors: Sahil Prabhnoor Sidhu, Vadim Iablokov, Vina Fan Reviewers: Brandon Hisey, Laura Byford-Richardson, Raafi Ali Dr. Sylvain Coderre* * MD at time of publication Local inflammation Diverticulitis Inflammation of diverticuli Conditions causing inherent weakness in bowel wall, i.e. aging, Ehlers-Danlos syndrome, Marfan syndrome Risk factors (i.e. low fiber diet, obesity, inactivity, smoking) contributing to reduced gut motility ↑Intraluminal pressure in the colon Herniation of colonic mucosa and submucosa through circular muscle at points of weakness to form outpouchings Diverticulosis Presence of outpouchings in the colon (diverticuli) Note: In Western populations, most diverticulosis is left-sided, whereas in Asian populations, these outpouchings are more often right-sided. Mucosal abrasion or micro-perforation by ↑ intraluminal pressure or dense food particles Bacterial overgrowth, dysbiosis and passage into the lamina propria Feces collects in diverticuli Gut bacteria metabolize undigested material and produce gas Stretching of colon Bloating wall irritates and visceral afferent flatulence nerves Episodic abdominal discomfort and cramping Blood vessels in the mucosa and submucosa (vasa recta) are stretched over the diverticuli, and may rupture from ↑ pressure Diverticular bleed Painless hematochezia (passage of fresh blood from the rectum) Inflammatory cytokines activate clotting factors Clotting of blood in vessels supplying diverticula Inflammatory cytokine release (IL-6, TNF-α) Cytokines enter systemic circulation Edema in the bowel wall Irritation of adjacent parietal peritoneum and somatic nerves Left lower quadrant (LLQ) pain, guarding Small abrasions are walled off by pericolic fat and mesentery ↑WBC Fever Inflammation may spread to nearby organs, leading to ulceration and abnormal connections between organs Pericolic abscess No hematochezia Local ischemia and focal necrosis resulting in loss of integrity of the bowel wall Perforation Generalized peritonitis Colonic obstruction (rare) Fistulae (rare): i.e. colovesical, coloenteric Stricture/fibros is formation with healing Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published October 12, 2016; Updated July 30, 2023 on www.thecalgaryguide.com

Knee Osteoarthritis

Authors: Jared Topham Knee Osteoarthritis: Pathogenesis and clinical findings Reviewers: Liam Thompson, Raafi Ali Yan Yu*, Kelley DeSouza* * MD at time of publication Primary Causes Secondary Causes Aging ↓ Synovial fluid in joint Gender Females > males Genetics Family history of osteoarthritis Race Black > Caucasian Joint malposition (e.g. valgus or varus) Articular trauma Inflammatory disease or infection (e.g. Rheumatoid or septic arthritis) Obesity and ↑leptin ↑ Chondrocytes, inflammatory mediators, and metalloproteinases Extracellular matrix degradation ↑ Knee joint loading forces Metabolic syndromes (e.g. diabetes mellitus) ↑ Oxidative stress and insulin resistance Low-grade systemic inflammation ↓ Elasticity and ↑ degradation of cartilage ↑ Friction in knee joint with movement ↓ Cartilage along femoral groove and posterior surface of patella Pain, catching, and crepitus (crackling/clicking sound) in the patellofemoral joint Inability/difficulty with kneeling or climbing stairs Abnormal distribution of forces accumulate and stress articular surface ↑ Damage/laxity to soft tissue structures stabilizing knee joint Knee Osteoarthritis (Multifactorial entity characterized by cartilage breakdown, deterioration of connective tissue, and bone deformities) ↓ Cartilage between distal femur and proximal tibia ↓ Joint spaceàto articular dysfunction Radiographic changes See Osteoarthritis (OA): X-Ray Features slide Repeated attempts to repair cartilage and joint disruption Subchondral bone thickening (sclerosis) under joint cartilage and bone spur (osteophyte) formation around joint line Rotational/antero-posterior instability and ↑ external adduction moments during walking Alterations in proteoglycans, fiber arrangement, and collagen composition in soft tissue structures within/around knee joint ↑ Shear forces and medial compartment narrowing erode and pinch soft tissue structures within the knee joint Cruciate ligament degeneration Weakened passive stabilizers of the knee joint Knee giving way and instability (falls) Meniscal tears, if large àprevents knee extension/flexion Locking of the knee Joint line tenderness: Patient points to area of tenderness/pain reproducible upon palpation Anatomical axis of hip, knee, and ankle joints ↑ loading medially Medial > lateral joint line tenderness ↑ Joint friction activating nociceptors in the surrounding anatomical tissues Injury and inflammation ↑ nociceptive responses in soft tissue structures and subchondral bone within knee joint Nociceptive feedback to brain inhibits activity of motor cortex neurons controlling muscles around the knee ↓ Motor output and muscle activation over time ↓ Muscle strength/endurance, lower limb muscle use, functional ability (walking, stairs, etc.) Joint inflammationà accumulation of fluid within joint Stiffness, swelling, redness, and pain Limited joint space reduces range of motion for femur to roll/slide on tibia ↓ Knee flexion and extension Flexion contracture and antalgic gait Reduced weight acceptance of the joint and surrounding muscles/tendons ↓ Mobility and physical dysfunction Muscular atrophy Reduced function of active stabilizers of the knee joint (quadriceps, adductors, hamstrings) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published July 30, 2023 on www.thecalgaryguide.com

Rotator Cuff Disease

Rotator Cuff Disease: Pathogenesis and clinical findings Authors: Jared Topham Reviewers: Raafi Ali, Yan Yu*, Kelley DeSouza* * MD at time of publication Aging Collagen fiber disorientation and myxoid degeneration Tendons, ligaments, and connective tissue are replaced by gelatinous and/or mucoid substance Obesity ↑ Loading on shoulder structures ↓ Static stability (from glenoid labrum and ligamentous components) of glenohumeral joint Tensile forces Repeated eccentric tension from overhead activities Trauma, sports, and occupation ↑ Torque, compression, and translational stresses Metabolic syndromes Reactive oxygen species interact with ↑ glucose forming advanced glycation end-products (AGEs) which accumulate in soft tissues Smoking Impingement syndromes Vessel damage, ischemia, tenocyte apoptosis Macro-trauma causing an acute, complete tear in the rotator cuff muscle(s) ↓Dynamic stability (from rotator cuff and periscapular muscles) and range of motion of the shoulder at the glenohumeral joint ↑ Bone on bone contact of proximal humeral head and boney structures of the scapula Subacromial bursa degeneration ↓ Protection of underlying supraspinatus muscle from attrition between humeral head and acromion Rotator Cuff Syndrome (Inflammation, impingement, or tearing of one or more of the four muscles/tendons of the rotator cuff: supraspinatus, subscapularis, infraspinatus, teres minor) Repetitive loading and micro-tearing of tendon/muscle fibers ↑ Oxidative stressors and inflammatory cascades ↓ Vascularity of rotator cuff structures Radiographic changes: See Rotator Cuff Disease: X-ray and ultrasound features slide, in addition to: calcific tendonitis, calcification of in the coracohumeral ligament, and hooked acromion (calcification from tendon pulling) In some cases, soft tissues enclose/surround shoulder joint capsule thicken (fibrose) and tighten Degenerative joint disease and rotator cuff arthropathy Proximal humeral head migration and ↓ subacromial space Inflammation and insufficient healing of rotator cuff structures, which may lead to: Supraspinatus (shoulder abduction) degeneration Pain, shoulder stiffness, ↓ active AND passive range of motion Adhesive Capsulitis (frozen shoulder) Infraspinatus and teres minor (external rotation) degeneration Rotator cuff tendons become inflamed and irritated as they rub against acromion Subacromial impingement Subscapularis (internal rotation) degeneration +Lift-off test: Inability to hold dorsum of the hand off lumbar spine while internally rotating shoulder ↓ Shoulder strength and muscular atrophy Pain with passive shoulder flexion beyond 90° Winging of the scapula during arm adduction +Empty-can test: Weakness and/or arm depression with resisted abduction with arm internally rotated in 90° +Drop-arm test: Inability to maintain shoulder in abducted position at 90° and/or adduct the arm in a controlled manner (resulting in ”dropping”) Weakness to resisted external rotation with elbow in 90° flexion, inability to keep arm externally rotated (infraspinatus) +Hornblower’s sign: decreased external rotation strength in arm abduction (suggests additional teres minor tear) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published July 30, 2023 on www.thecalgaryguide.com

Low Ankle Sprain

Low Ankle Sprain: Pathomechanics and Clinical Findings Authors: Parker Lieb, Joseph Kendal Reviewers: Liam Thompson, Tara Shannon, Sunawer Aujla, Stephanie de Waal, Amanda Eslinger, Dave Nicholl, Maninder Longowal Gerhard Kiefer* * MD at time of publication Talus subluxation with anterior force on heel + Anterior drawer test Recurrent sprains Synovial inflammation & hypertrophy Remodeling of collagen and bone Degenerative changes (e.g., osteophytes, subchondral sclerosis) Ankle eversion beyond normal range (less common) Excessive stress to medial ankle deltoid ligament Ankle plantar flexion and inversion beyond normal range (most common) Excessive stress to lateral ankle ligament(s) Associated fracture of malleolus or subtalar joint Bone pain, inability to weight bear Recruitment of inflammatory cells to damaged area ↑ Local pro- inflammatory cytokines ↑ Capillary permeability & vasodilation to damaged area Collagen fibers in ligament(s) rupture Low Ankle Sprain (medial or lateral) Local blood vessels tear Blood leaks into surrounding tissue Grade I Mild injury Grade II Moderate injury Grade III Severe injury Minimal ligament disruption Incomplete ligament tear Complete ligament tear No joint laxity Joint laxity Gross joint laxity Mechanical and functional instability Decreased ankle joint space Ankle Impingement (compression of soft and/or bony structures in joint) Chronic ankle instability Damage to mechanoreceptors in muscles surrounding ankle joint Bruising Swelling Focal tenderness over torn ligament(s) Pain on injury and with weight bearing Impaired proprioception & neuromuscular control Nociceptors activated by trauma and inflammatory factors Falls Antalgic gait Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Nov 9, 2014; updated Aug 15, 2023 on www.thecalgaryguide.com

Rotator Cuff Disease Xray and Ultrasound Features

Rotator Cuff Disease: X-ray and ultrasound features Rotator cuff tears can affect each of the muscles making up the rotator cuff individually, or in combination Authors: Jared Topham Reviewers: Raafi Ali, Kelley DeSouza* * MD at time of publication Supraspinatus tear (most common) Chronic (>3 months) tear with degenerative-type changes Rotator cuff insufficiency, loss of supporting structures holding humeral head inferiorly Displacement of the humeral head anterosuperiorly and instability of joint Microtrauma affecting superior aspect of glenohumeral joint “Acetabularization” or coracoacromial arch: concave acromial erosion and increased sclerosis (hardening) Subscapularis tear (second most common) Teres minor tear Infraspinatus tear Rotator Cuff Syndrome (Inflammation, impingement, or tearing of one or more of the four muscles/tendons of the rotator cuff: supraspinatus, subscapularis, infraspinatus, teres minor) Acute (partial or full thickness) tear of rotator cuff tendons Humeral subluxation (partial displacement of humeral head relative to glenoid) High riding humerus: decreased acromial humeral distance Decreased acromial humeral interval/space (impinging tendons of rotator cuff) Full: Defect extends from the subacromial bursa (fluid filled sack beneath the acromion and above the rotator cuff tendons) to the articular surface of the glenohumeral joint Tendon/muscle fibers completely separated from bone and/or muscle fiber connections severed Partial: Focal defect affecting a portion of the tendon which may involve the bursa or glenohumeral articular surface Non-visualization of the tendon Acetabularization of glenoid Fluid replaces empty space of tendon tear Overlying fat around the sub acromial bursa falls into tendon gap Sagging peribursal fat sign on ultrasound “Femoralization” of the humerus: bone erosion (destruction) and rounding of greater tuberosity Osteoarthritis of glenohumeral joint: See Osteoarthritis (OA): X-ray features slide Hyperechoic (brightened) line between articular cartilage of humeral head and muscle tendon on ultrasound Cartilage interface sign on ultrasound Hypoechoic (darkened) tendon outline discontinuity on ultrasound imaging Femoralization (rounding) of greater tuberosity Subluxation of the humeral head relative to the glenoid Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published September 6, 2023 on www.thecalgaryguide.com

Acute Respiratory Distress Syndrome

Acute Respiratory Distress Syndrome: Pathogenesis and clinical findings Acute respiratory distress syndrome (ARDS) is a clinical syndrome involving acute lung injury. It results in severe hypoxemia and bilateral Authors: David Olmstead Mao Ding Reviewers: Midas (Kening) Kang Usama Malik Kevin Solverson* * MD at time of publication ↓ PaO2 (Partial pressure of oxygen in arterial blood ↓SpO2 (Peripheral oxygen saturation) Tachypnea (↑ RR) Tachycardia (↑ HR) Dyspnea Bilateral Opacity on chest radiograph ↓ PaO2, ↓SpO2 ↑ PaCO 2 ↑ PaO2, ↓PaCO2 Eupnea (normal breathing) ↓ O2 Requirements Depression, Anxiety, PTSD Neuromuscular Weakness Chronic Respiratory Dysfunction airspace disease in the absence of elevated left-heart pressures. Direct Lung Injury Causes include pneumonia and pulmonary sepsis (community- acquired, hospital-acquired, aspiration, viral), drowning, and chemical pneumonitis from aspiration or direct inhalational injury Indirect Lung Injury Causes include sepsis with a non-pulmonary source, trauma, severe burns, transfusion- related acute lung injury (TRALI) and pancreatitis Lung Tissue Inflammation Exudative: Neutrophils migrate into the alveoli in response to inflammatory stimulus Note: While the three phases of ARDS take place in sequence, all areas of the lung may not be in the same phase at the same time. For this reason, the processes can be thought of as overlapping. Proliferative: Body attempts to heal damage. If it is not successful, the tissue transitions to the fibrotic phase Neutrophil-containing pulmonary exudate interferes with surfactant function Neutrophil infiltration and proinflammatory cytokines lead to tissue edema, dysfunction and subsequent destruction of pulmonary epithelium Residual debris in alveoli are cleared by phagocytic cells Restoration of alveolar epithelial cells. Alveoli collapse in absence of working surfactant Damaged epithelium impairs gas exchange Pulmonary capillaries do not adequately absorb fluid The body’s attempts to heal lung tissue result in deposition of hyaline membranes in the alveoli Ventilation- Perfusion Mismatch Pulmonary Edema Impaired Gas Diffusion Functional epithelium is able to absorb fluid back into circulation ↑ useful surface area for gas exchange Clearing of CXR Impaired Function After Prolonged Illness Pulmonary Hypertension Fibrotic: Inadequate healing results in long-term pulmonary damage (rare) Fibroblast activity leads to deposition of collagen in alveoli and alveolar capillaries Fatigue Pulmonary Fibrosis Nail Clubbing (nails appear wider & swollen) Cough/Dyspnea Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Feb 6, 2018, updated Oct 10, 2023 on www.thecalgaryguide.com Acute Respiratory Distress Syndrome: Note: Acute respiratory distress syndrome is a clinical Authors: David Olmstead Reviewers: Midas (Kening) Kang Usama Malik Kevin Solverson* * MD at time of publication Pathogenesis and clinical findings Direct Lung Injury Causes include pneumonia and pulmonary sepsis (community-acquired, hospital-acquired, aspiration, viral), drowning, and chemical pneumonitis from aspiration or direct inhalational injury Indirect Lung Injury syndrome involving acute lung injury. It results in severe hypoxemia and bilateral airspace disease in the absence of elevated left-heart pressures. Causes include sepsis with a non-pulmonary source, trauma, severe burns, transfusion-related acute lung injury (TRALI) and pancreatitis Lung Tissue Inflammation Exudative: Neutrophils migrate into the alveoli in response to inflammatory stimulus Note: While the three phases of ARDS take place in sequence, all areas of the lung may not be in the same phase at the same time. For this reason, the processes can be thought of as overlapping. Proliferative: Body attempts to heal damage. If it is not successful, the tissue transitions to the fibrotic phase Neutrophil-containing pulmonary exudate interferes with surfactant function Neutrophil infiltration and proinflammatory cytokines lead to tissue edema, dysfunction and subsequent destruction of pulmonary epithelium Abbreviations: PaO2: Partial pressure of oxygen in arterial blood SpO2: Peripheral oxygen saturation. CXR: Chest radiograph. Residual debris in alveoli are cleared by phagocytic cells Restoration of alveolar epithelial cells. Alveoli collapse in absence of working surfactant Damaged epithelium impairs gas exchange Pulmonary capillaries do not adequately absorb fluid The body’s attempts to heal lung tissue result in deposition of hyaline membranes in the alveoli Ventilation- Perfusion Mismatch Pulmonary Edema Impaired Gas Diffusion ↓ PaO2, ↓SpO2 Tachypnea Tachycardia Dyspnea Bilateral Opacity on CXR ↓ PaO , ↓SpO 2 2 ↑ PaCO2 ↑ PaO2, ↓PaCO2 Eupnea ↓ O2 Requirements Clearing of CXR Depression, Anxiety, PTSD Neuromuscular Weakness Chronic Respiratory Dysfunction ↑ useful surface area for gas exchange Functional epithelium is able to absorb fluid back into circulation Impaired Function After Prolonged Illness Fibrotic: Inadequate healing results in long-term pulmonary damage (rare) Fibroblast activity leads to deposition of collagen in alveoli and alveolar capillaries Pulmonary Fibrosis Pulmonary Hypertension Cough/Dyspnea Nail Clubbing Fatigue Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published February 06, 2018 on www.thecalgaryguide.com

Approach To Dementia

Approach to Dementia/Major Neurocognitive Disorder (NCD) Authors: Iqra Rahamatullah Mahrukh Kaimkhani Reviewers: Yvette Ysabel Yao Mao Ding Gary Michael Klein* *MD at time of publication 1) Changes noticed? Modest ↓cognitive performance from previous, DOES NOT interfere with daily independence MILD COGNITIVE IMPAIRMENT More pronounced ↓cognitive performance from previous, DOES interfere with daily independence MILD TO MODERATE DEMENTIA ↓Cognitive performance, difficulty with ≥1 basic activities of daily living (ADL) or ≥2 instrumental ADLs MODERATE TO SEVERE DEMENTIA DEMENTIA Fluctuating course, acute onset, inattention WITH either disorganized thinking or altered level of consciousness DELIRIUM 2) Is it dementia? Normal, age-related: ↓focus, ↓cognitive speed, ↓reaction time, ↓memory NORMAL COGNITIVE DECLINE 3) What is the cause of the dementia? (main causes discussed here) Loss of cognitive functioning, including memory, language, problem solving, and other thinking abilities, that interferes with independence in everyday activities Beta-secretase cleaves beta amyloid protein Atherosclerosis or thrombosis Misfolded alpha- synuclein Toxic beta amyloid plaque and tau tangle (sticky) formation Ischemia to areas of brain (strokes) Build ups and deposition within neurons (Lewy bodies) Disrupted signaling, inflammation, hippocampal and cerebral impairment Necrosis of brain tissue in areas impacted by strokes Neuronal impairment and atrophy (especially in substantia nigra) Neuronal atrophyàfrontal + temporal lobe atrophy Progressive atrophy of basal ganglia and dorsal striatum + lateral ventricles expanding Death of dopaminergic neurons in substantia nigra Alzheimer’s Dementia Vascular Dementia Lewy Body Dementia Frontotemporal Dementia Huntington’s Disease Parkinson’s Disease ↓Memory, ↓learning, ↓language skills, disorientation, inattention Total debilitation, fatal infections Findings vary depending on area Step-wise worsening impairment Parkinsonism, hallucinations, REM- sleep behavior disorder Total debilitation, dependence Personality and behavioral changes Mental status changes Chorea, ↓cognition, mood changes Aspiration, dementia, suicide Resting tremor, rigidity, anosmia Depression, dementia, falls Abnormal protein inclusions and tangles (usually tau) form in neurons Autosomal dominant disease (with anticipation) with ↑CAG repeats in Huntingtin gene Genetic mutations, environmental exposures, or idiopathic cause Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published September 17, 2023 on www.thecalgaryguide.com Approach to Dementia/Major Neurocognitive Disorder (NCD) Authors: Iqra Rahamatullah Mahrukh Kaimkhani Reviewers: Yvette Ysabel Yao Fluctuating course, acute onset, inattention WITH either disorganized thinking or altered level of consciousness (LOC)? DELIRIUM 1) Changes noticed? 2) Is it dementia? Normal, age-related: ↓focus, ↓cognitive speed, ↓reaction time, ↓memory NORMAL COGNITIVE DECLINE Modest ↓cognitive performance from previous, DOES NOT interfere with daily independence MILD COGNITIVE IMPAIRMENT More pronounced ↓cognitive performance from previous, DOES interfere with daily independence MILD TO MODERATE DEMENTIA ↓Cognitive performance, difficulty with ≥1 basic activities of daily living (ADL) or ≥2 instrumental ADLs MODERATE TO SEVERE DEMENTIA 3) What is the cause of the dementia? (main causes discussed here) Beta-secretase cleaves beta amyloid protein Atherosclerosis or thrombosis Misfolded alpha-synuclein Toxic beta amyloid plaque and tau tangle (sticky) formation Ischemia to areas of brain (strokes) Build ups and deposition within neurons (Lewy bodies) Disrupted signaling, inflammation, hippocampal and cerebral impairment Necrosis of brain tissue in areas impacted by strokes Neuronal impairment and atrophy (especially in substantia nigra) Neuronal atrophyàfrontal + temporal lobe atrophy Progressive atrophy of basal ganglia and dorsal striatum + lateral ventricles expanding Death of dopaminergic neurons in substantia nigra Alzheimer’s Dementia Vascular Dementia Lewy Body Dementia Frontotemporal Dementia Huntington’s Disease Parkinson’s Disease ↓Memory, ↓learning, ↓language skills, disorientation, inattention Total debilitation, fatal infections Findings vary depending on area Step-wise worsening impairment Parkinsonism, hallucinations, REM- sleep behavior disorder Total debilitation, dependence Personality and behavioral changes Mental status changes Chorea, ↓cognition, mood changes Aspiration, dementia, suicide Resting tremor, rigidity, anosmia Depression, dementia, falls DEMENTIA Loss of cognitive functioning, including memory, language, problem solving, and other thinking abilities, that interferes with independence in everyday activities Abnormal protein inclusions and tangles (usually tau) form in neurons Autosomal dominant disease (with anticipation) with ↑CAG repeats in Huntingtin gene Genetic mutations, environmental exposures, or idiopathic cause Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published September 17, 2023 on www.thecalgaryguide.com

Mitral Regurgitation Pathogenesis and clinical findings

Mitral Regurgitation: Pathogenesis and clinical findings Coronary Artery Disease Authors: Juliette Hall, Victoria Nkunu Reviewers: Raafi Ali, Jack Fu, Usama Malik, Sina Marzoughi, Jason Waechter* * MD at time of publication (Ischemic Heart Disease & Myocardial Infarction) Myocarditis Left ventricular dilation displaces papillary muscles Dilation of the Tethering of mitral valve annulus chordae tendineae ↑ Volume and pressure in left atrium ↑ Volume pushed back into left ventricle Dilated left ventricle Apical impulse on palpation and auscultation ↓ Forward flow of blood out of heart Blood backs up into pulmonary circulation ↑ Intravascular hydrostatic pressure in pulmonary vessels Fluid extravasates out of vessels and into the lungs Papillary muscle rupture Mitral valve leaflets flail Mitral valve prolapse Structurally abnormal valve Connective tissue disorders Weak valve leaflets Rheumatic heart disease Dilatation of the mitral valve annulus, inflammation of leaflets Infective endocarditis Vegetations form on valve leaflets Mitral Regurgitation Blood consistently flows backward throughout systole Holosystolic murmur, radiates to axilla, ↑ with afterload (e.g. making a fist) Backflow of blood from left ventricle to left atrium due to impaired mitral valve closure S3 heart sound Myocardial remodeling ↓ Muscle efficiency ↓ Left ventricle systolic function ↓ O2 saturation, tachypnea, wheeze, ↑ work of breathing, crackles, frothy sputum (if severe) Congestive heart failure ↓ Stroke volume ejected into aorta ↓ Cardiac output ↓ Organ perfusion ↓ O2 to kidney Activation of renin-angiotensin- aldosterone system ↑ Reabsorption of water by kidneys ↑ Intravascular hydrostatic pressure systemically Peripheral edema Injury to kidney parenchyma ↓ ability for kidney to clear creatinine ↑ Serum creatinine Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Feb 3, 2018, updated Oct 15, 2023 on www.thecalgaryguide.com

Statins Mechanisms and Side Effects

Statins: Mechanisms of action & side effects Authors: Rupali Manek, Julia Iftimie Reviewers: Gurreet Bhandal, Raafi Ali, Joshua Dian, Laura Byford-Richardson Samuel Fineblit*, Alexander Ah-Chi Leung* * MD at time of publication Competitive inhibitors of HMG-CoA reductase (rate-limiting enzyme in cholesterol synthesis) ↓ Coenzyme Q10 (ubiquinone) ↑ Mitochondrial superoxide ↓ Hepatic membrane stability ↓ Conversion of HMG-CoA to mevalonic acid ↑ Hepatic VLDL uptake ↓ Hepatic apolipoprotein B-100 secretion ↓ Oxidative phosphorylation Impaired mitochondrial function ↑ Liver enzyme leakage ↓ Mitochondrial ATP production ↑ Aminotransferases enzymes in liver ↑ Clearance of LDL cholesterol from bloodstream Myopathy/ myalgias (muscle aches) Hepatotoxicity ↓ Circulating LDL cholesterol ↓ LDL, ↑ HDL, ↓ TG ↓ Hepatic cholesterol synthesis ↓ VLDL synthesis ↑ Cell surface LDL receptor expression Statins First line therapy for treating hypercholesterolemia (↑ LDL cholesterol in blood) Common examples: rosuvastatin, atorvastatin, simvastatin, pravastatin, etc. ↑ Apolipoprotein AI production & ↑ hepatic HDL neogenesis ↓ TG ↑ HDL ↑ Vasodilation ↓ C-reactive protein ↓ Impacts of coagulation cascade ↓ Atherosclerosis (plaque along walls of blood vessels) ↓ Cardiovascular disease & mortality Pleotropic effects (i.e. non lipid related effects) Abbreviations: HMG-CoA – Hydroxymethylglutaryl-CoA LDL – Low-density lipoprotein VLDL – Very low density lipoprotein HDL – High density lipoprotein TG – Triglycerides Inhibition of synthesis of isoprenoid intermediates in the mevalonate pathway ↑ Nitric oxide activity ↓ Inflammation ↓ Tissue factor expression ↓ Macrophage proliferation ↓ Tissue factor (promotes macrophage mediated thrombus formation) ↑ Blood flow & endothelial function ↓ Thrombin generation ↓ Metalloproteinases expression ↑ Inhibition of metalloproteinase-1 ↓ Thrombogenicity (production of blood clot/thrombus) Plaque stabilization (↓ risk of atherosclerotic plaque rupture, myocardial infarction, and stroke) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Physiological Outcome Published July 9, 2017, updated Nov 6, 2023 on www.thecalgaryguide.com

Pharmacotherapy for Dyslipidemia Overview

Pharmacotherapy for Dyslipidemia: General overview Dyslipidemia Authors: Rupali Manek Reviewers: Gurreet Bhandal, Raafi Ali, Yan Yu*, Samuel Fineblit* *MD at time of publication Hypolipidemia (↓ HDL or ↓ apoB containing lipoproteins like LDL) Bile-acid sequestrants Bind bile acids in intestinal lumen to prevent reabsorption by enterohepatic (gut-liver) circulation ↑ Excretion of bile acids and cholesterol in stool ↓ LDL in blood Side effects: GI disturbances, commonly interact with other drugs by interfering with absorption See Calgary guide slide on “Bile-acid sequestrants: Mechanisms of action & side effects” for complete description of mechanism and side effects (clinical imbalance of lipids) Hypertriglyceridemia (if VLDL mediated & in need of treatment for pancreatitis prevention) Hypercholesteremia (↑ LDL in blood) Ezetimibe Inhibits cholesterol absorption via NPC1L1 transporter ↑ Hepatic (liver) LDL receptor expression ↑ LDL clearance from blood ↓ LDL in blood Avoid in pregnancy See Calgary guide slide on “Ezetimibe: Mechanisms of action & side effects” for complete description of mechanism and side effects Combined hyperlipidemia (↑ Triglycerides and ↑ cholesterol) Statins (ex. rosuvastatin, atorvastatin, simvastatin, pravastatin) Competitive inhibitors of HMG-CoA reductase (rate-limiting enzyme in cholesterol synthesis) Fibrates (ex. fenofibrate, gemfibrozil) Activate PPAR! (nuclear receptor) ↑ Lipolysis (breakdown of lipids) and free fatty acid oxidation ↓ Triglycerides in blood Side effects: GI discomfort, rash, pruritis Contraindicated in pregnancy, renal failure, liver & gallbladder disease See Calgary guide slide on “Fibrates: Mechanisms of action & side effects” for complete description of mechanism and side effects PCSK9 inhibitors (ex. evolocumab and alirocumab which are monoclonal antibodies) Inhibit PCSK9 (holds the LDL:LDL receptor complex together as it is internalized into the cell for destruction of LDL) LDL receptor returns to surface without being destroyed ↑ LDL receptor expression ↑ LDL clearance from blood ↓ LDL in blood See Calgary guide slide on “PCSK9 Inhibitors: Mechanisms of action & side effects” for complete description of mechanism and side effects ↓ Cholesterol synthesis in liver ↑ LDL receptor expression in liver LDL receptor recognizes apoB100 (structural protein on LDL) and apoE (structural protein found on chylomicron, VLDL, IDL) ↑ Clearance of LDL cholesterol from bloodstream ↓ LDL cholesterol in blood ↑ HDL in blood ↓ Triglycerides in blood ↓ Atherosclerosis (plaque along walls of blood vessels) Abbreviations: HDL – High density lipoprotein; HMG-CoA – Hydroxymethylglutaryl- CoA; LDL – Low-density lipoprotein; PCSK9 – Proprotein convertase subtilisin/kexin type 9; PPAR! – Peroxisome proliferator-activated receptor alpha; NPC1L1 – Niemann-Pick C1-Like 1; VLDL – Very low-density lipoprotein Side effects: Myalgias (muscular aches), rhabdomyolysis (muscle breakdown), transaminitis (liver inflammation), liver failure, ↑ risk of diabetes mellitus Contraindicated in pregnancy See Calgary guide slide on “Statins: Mechanisms of action & side effects” for complete description of mechanism and side effects Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Nov 6, 2023 on www.thecalgaryguide.com

Death Cardiovascular Respiratory and Neurologic Mechanisms

Death: Cardiovascular, Respiratory and Neurologic Mechanisms Mitochondria in tissues unable to utilize O2 Reduced hemoglobin in blood to carry O2 Low oxygen content in blood (CaO2) Hypoxemia (Type I Respiratory Failure): low dissolved oxygen in blood (PaO2) Lungs can’t oxygenate blood fast enough Lungs can’t rid blood of CO2 fast enough Hypercapnia / hypercarbia (Type II Respiratory Failure): elevated dissolved CO2 in blood (PaCO2) Cerebral vasodilation Toxins: e.g. cyanide, pesticides, arsenic Severe anemia Distributive problems: Systemic inflammation (sepsis, anaphylaxis, pancreatitis), adrenal insufficiency, vasodilatory drugs Obstructive problems: Cardiac tamponade*, tension pneumothorax* or massive pulmonary embolism* Hypovolemic* problems (low blood volume): Hemorrhage, dehydration, widespread skin disruption or burns Cardiac valve dysfunction Myocardial infarction* or cardiomyopathy Cardiac arrhythmia or heart block Disturbed electrical activity in cardiomyocytes Peripheral metabolic disturbances Hypokalemia*, Hyperkalemia* Acidosis* (including renal failure) Hypothermia* Toxins* (e.g. cocaine, beta blockers, tricyclics) Severe thyroid derangement Inappropriate systemic vasodilation Adjacent forces impair heart filling Low cardiac preload Low stroke volume (SV; depends on valves, contractility, preload) Decreased systemic vascular resistance (SVR) Low blood pressure (BP = CO x SVR) Decreased cardiac output (CO = SV x HR) Disseminated intravascular coagulationàwidespread thrombi that occlude blood flow (also causes hemorrhage, see relevant box at left) Methemoglobinemia: some hemoglobin gets stuck in a state that can’t carry O2 Hemoglobin has reduced capacity to carry or release O2 Drugs: e.g. dapsone, nitrates Carbon monoxide poisoning Circulatory collapse / shock: inadequate perfusion of tissue with blood Respiratory collapse: blood has insufficient useable O2 content Ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) Hypoxia*: inadequate O2 delivery or utilization in tissues Hypoxia creates metabolic disturbances that impair cardiac cells. Alternatively, any of the preceding conditions marked with (*) can directly trigger cardiac arrest first Pulseless Electrical Activity (PEA): organized activity on ECG with no cardiac output (can be preceded or mimicked by pseudo-PEA, in which there is still some output on ultrasound) Low atmospheric pressure or oxygen content Severe lung disease Asthma, COPD, interstitial lung disease, congestive heart failure, pulmonary hypertension, pulmonary embolism, lung collapse / atelectasis Acute respiratory distress syndrome Pneumonia, aspiration pneumonitis, inhalational injury, systemic inflammation, drowning Severe hypoventilation Respiratory fatigue, advanced COPD, chest wall disorders, neuromuscular disorders, upper airway obstruction, toxins (e.g. opioids, botulism) Can degenerate at any time Asystole: no cardiac electrical activity or output Death Respiratory arrest: cessation of breathing Inability to protect airway Decreased level of consciousness Note This is a broad overview of the many scenarios that can result in death. For detailed explanations of the various disease mechanisms, refer to the corresponding slides. * = reversible causes of cardiac arrest (Hs and Ts) Author: Ben Campbell Reviewers: Yan Yu* Huma Ali* * MD at time of publication Bradycardia (low heart rate, HR) Unopposed parasympathetic stimulation of heart (can also cause vasodilation, see Distributive problems) Disruption of spinal cord sympathetic control Injury to cervical or upper thoracic spinal cord Irreversible cessation of cardiac, respiratory, and brain function Prolonged seizure initially causes increased cardiovascular activity, until the system fatigues Disruption of respiratory control center in medulla Expanding skull contents squeeze brainstem (herniation) Increased intracranial pressure Edema from intracranial hemorrhage, trauma, brain mass Edema, inflammation, hypoxia and/or metabolic derangements cause diffuse neuron dysfunction Central nervous system infection Dementia, particularly with delirium Massive ischemic stroke Seizure activity prevents or alters breathing Metabolic disturbances that affect the central nervous system Hypoglycemia Hypocalcemia, hypercalcemia Hyponatremia, hypernatremia Uremia Acute liver failure (hyperNH4) Many drugs / toxins Withdrawal (e.g. EtOH) Status epilepticus Brainstem lesion (e.g. stroke, neoplasm, inflammatory) Nervous System Insult Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 11, 2023 on www.thecalgaryguide.com Respiratory System Insult Cardiovascular System Insult Cardiogenic problems

Non-Alcoholic Fatty Liver Disease

Non-Alcoholic Fatty Liver Disease: Pathogenesis and clinical findings Diagnosis of Metabolic Syndrome when ≥ 3 out of the 5 preceding risk factors are present Authors: Stephanie Happ Reviewers: Obesity Hypertension Diabetes Hypertriglyceridemia Hypercholesterolemia Iffat Naeem Sunawer Aujla Edwin Cheng* * MD at time of publication Insulin resistance develops in adipose tissue and hepatocytes ↓ Ability of insulin to suppress lipolysis of adipose tissue ↑ Delivery of free fatty acids from adipocytes to the liver ↑ De-novo lipogenesis in the liver Hepatic Steatosis: accumulation of fat in the liver (in the absence of alcohol consumption, termed Non-Alcoholic Fatty Liver (NAFL)) Steatohepatitis: chronic inflammatory and apoptotic climate in the hepatocytes (in the absence of alcohol consumption, termed Non-Alcoholic Steatohepatitis (NASH)) Fibrosis of the Liver: excessive scarring of liver tissue resulting from chronic inflammation, although liver architecture is largely intact Fat droplets form and grow in the hepatocytes Hepatic mitochondria increase their workload in attempt to break down the excess free fatty acids through beta-oxidation ↑ in cellular workload creates more reactive oxygen speciesà Inflammation and apoptosis of hepatocytes On-going inflammation damages hepatic stellate cells (the primary extracellular matrix–producing cells of the liver) causing the release of fibrinogenic cytokines Cirrhosis of the liver: normal lobular structure distorts and is replaced by regenerating nodules and bridging septa, disrupting normal liver blood flow Deposition of fibrotic material and collagen within the perisinusoidal spaces of the liver Decompensated Cirrhosis Hepatocellular carcinoma Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published November 25, 2023 on www.thecalgaryguide.com

RICE mechanism of action

Rest, Ice, Compression, Elevation (RICE): Mechanism of action Healing of an injury requires pain and inflammatory control to encourage activity. The goal of Rest, Ice, Compression, Elevation (RICE) is to decrease inflammation. Though activity itself will contribute to pain and inflammation, it is integral to the rehabilitation process. Authors: Matthew Roberts Emma Windfeld Reviewers: Alexander Arnold Amanda Eslinger Shyla Bharadia Mao Ding Bradley Jacobs* * MD at time of publication Rest: (weight bearing or stressful motion discontinued) Further damage to affected tissues from mechanical stress is prevented Ice: (applied to injury) Compression: (wrap applied to injured area) Mechanical force applied to tissue Excess fluid is pushed back into capillaries and lymph network Elevation: (limb raised above heart) Blood flow to tissue is constricted Mechanism not well understood ↓ delivery of inflammatory mediators such as polymorphonuclear neutrophils and macrophages to injured site ↓ production of inflammatory cytokines (pro-inflammatory substances) such as Tumor Necrosis Factor-α, Platelet Derived Growth Factor, Epidermal Growth Factor, and Transforming Growth Factor-β ↓ Inflammation Gravity ↑ venous blood return to systemic circulation ↓ edema (accumulation of fluid in interstitium) Early initiation of injury-specific rehabilitative exercises improves range of motion, strength, and proprioception Stress to targeted area induces inflammation that, when tightly regulated, is integral to repair Injured muscle, tendon, bone, or ligament is strengthened ↓ Pain ↑Range of motion and therefore function Early recovery from injury Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Dec 9, 2013, updated Oct 15, 2023 on www.thecalgaryguide.com Rest, Ice, Compression, Elevation (RICE): Mechanism of action Healing of an injury requires pain and inflammatory control to encourage activity. The goal of Rest, Ice, Compression, Elevation (RICE) is to decrease inflammation. Though activity itself will contribute to pain and inflammation, it is integral to the rehabilitation process. Authors: Matthew Roberts Emma Windfeld Reviewers: Alexander Arnold Amanda Eslinger Shyla Bharadia Bradley Jacobs* * MD at time of publication Rest: (weight bearing or stressful motion discontinued) Further damage to affected tissues from mechanical stress is prevented Ice: (applied to injury) Compression: (wrap applied to injured area) Mechanical force applied to tissue Excess fluid is pushed back into capillaries and lymph network Elevation: (limb raised above heart) Gravity ↑ venous blood return to systemic circulation Blood flow to tissue is constricted ↓ delivery of inflammatory mediators such as polymorphonuclear neutrophils and macrophages to injured site Mechanism not well understood ↓ production of inflammatory cytokines (pro- inflammatory substances) such as Tumor Necorsis Factor-α, Platelet Derived Growth Factor, Epidermal Growth Factor, and Transforming Growth Factor-β ↓ Inflammation ↓ Pain ↓ edema (accumulation of fluid in interstitium) ↑Range of motion and therefore function Early initiation of injury- specific rehabilitative exercises improves range of motion, strength, and proprioception Stress to targeted area induces inflammation that, when tightly regulated, is integral to repair Injured muscle, tendon, bone, or ligament is strengthened Early recovery from injury Legend: Published MONTH, DAY, YEAR on www.thecalgaryguide.com Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications RICE: Mechanism of action Authors: Matthew Roberts Emma Windfeld Reviewers: Alexander Arnold Amanda Eslinger Shyla Bharadia Bradley Jacobs* * MD at time of publication Rest (weight bearing or stressful motion discontinued) Ice (applied to injury) Compression (wrap applied to injured area) Elevation (limb raised above heart) Constricts blood flow to tissue Mechanism not well understood Mechanical force applied to tissue ↓ Delivery of polymorphonuclear neutrophils and macrophages to injured site Excess fluid pushed back into capillaries and lymph network Gravity ↑ venous blood return to systemic circulation Prevents further damage to affected tissues from mechanical stress ↓ Production of inflammatory cytokines ↓ Edema (accumulation of fluid in interstitium) ↓ Inflammation ↓ Pain ↑Range of motion and therefore function Early initiation of injury-specific rehabilitative exercises to improve range of motion, strength, and proprioception Stress to targeted area induces inflammation that, when tightly regulated, is integral to repair Injured muscle, tendon, bone, or ligament is strengthened Early recovery from injury Legend: Published MONTH, DAY, YEAR on www.thecalgaryguide.com Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications

Aspiration Pneumonia

Aspiration Pneumonia: Pathogenesis and clinical findings Intractable vomiting ↑ Likelihood of oropharyngeal and gastric contents exiting the esophagus, entering the trachea to the lung If the acidic gastric contents are sterile, then aspirating this results in inflammation and lung injury without development of infection Aspiration pneumonitis Alveolar macrophages recruit neutrophils to local site of infection. Subsequent cytokine release compromises the vascular endothelial cell wall barrier and ↑ alveolar-capillary permeability ↑ inflammation due to fluid and cellular debris build-up in alveoli overdose (e.g. opioids) (e.g. stroke) Altered level of consciousness and impaired cough/clearance Tube Poor Alcohol and Substance Medications Neurologic diseases Esophageal and gastric motility disorders Impaired swallowing Chronic obstructive pulmonary disorder feeding oral health Bacteria adhere to epithelial surfaces and ↑ risk of airway and lung bacterial colonization Aspirated oropharyngeal and gastric contents can also contain bacteria ↓ Elimination and clearance of foreign bacteria from airway and lung Macroaspiration (large volume aspiration) of oropharyngeal bacteria, during eating and drinking Bacteria and fluid fill bronchi and alveolar space Aspiration Pneumonia Alterations to lung microbial flora An infectious lung process caused by inhalation of foreign bacterial and oropharyngeal and gastric contents Aspiration of acidic fluid and pneumonia causative pathogen (typically anaerobes or bacteria in normal oral flora) with resultant inflammation Infiltrate develops in a gravity-dependent pattern in patches around bronchi segments. Produces proinflammatory cytokines, (e.g. tumor necrosis factor-alpha, and interleukin-1) Hypothalamic production of prostaglandin E2 results in thermogenesis Fever Authors: Luiza Radu Reviewers: Mao Ding, *Yan Yu, *Jonathan Liu *MD at time of publication Aspiration to the right lung more common due to large diameter and more vertical orientation of the right main bronchus Crackles and ↑ lung vibrations (fremitus) on auscultation Productive Cough Impaired alveolar gas exchange Chemoreceptor detection of ↓ pO2 triggers ↑ ventilation Hypoxemia Dyspnea Consolidation in lower lobes (particularly superior segments) and posterior segments of upper lobes If untreated, a pus-filled lung cavity develops (e.g. abscess) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Jan 11, 2024 on www.thecalgaryguide.com

Shoulder Impingement Syndrome

Shoulder Impingement Syndrome: Signs and Symptoms Calcific deposition Abnormal shoulder morphology Static subacromial narrowing Abnormal scapular rotation and tilt Scapular winging Weakness Degenerative changes to rotator cuff tendons Weakness Dynamic subacromial narrowing Repetitive overhead activity/shoulder overuse Muscle fatigue Repetitive compression forces on subacromial space Glenohumeral instability or stiffness Authors: Janelle Wai Dalal Awwad Reviewers: M. Patrick Pankow Reza Ojaghi Usama Malik Sunawer Aujla Ryan Shields* * MD at time of publication Internal/ Posterior Impingement Compression of rotator cuff tendons between humeral head and posterosuperior glenoid edge during end stage of throwing Pain with passive extension and lateral rotation + Posterior Internal Impingement Test Instability: Laxity of glenohumera l joint Stiffness: Scapular winging with downward tilt, shoulder protraction Primary/ Structural Impingement Any anatomical abnormalities Secondary/Functional Impingement Normal anatomy with motion abnormalities Impingement of underlying rotator cuff muscle-tendon unit and inflammation of subacromial bursa Rotator Cuff Syndrome External/ Subacromial Impingement Compression of subacromial bursa and rotator cuff (i.e. supraspinatus tendon) on the anterolateral acromion and coracoacromial ligament X-Ray: Normal Ultrasound: +/- Tendinopathy, muscle atrophy Pain with overhead movement Pain at night (e.g., sleep position, gravity) Pain with lifting (e.g., weight- training, groceries) Pain (between 60°-120°) with passive shoulder abduction + Painful arc Test Pain with passive shoulder flexion + Neer’s Test Pain with passive shoulder flexion (to 90°) + internal rotation + Hawkins-Kennedy test Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications First published May 27, 2018; updated Jan 11, 2024 on www.thecalgaryguide.com

Arachnoid Cysts MRI Findings

Arachnoid Cysts: Findings on MRI Imaging source: radiopaedia.org Authors: George S. Tadros Reviewers: Matthew Hobart, Shahab Marzoughi, James Scott* * MD at time of publication Extra-Axial Location Cyst is visualized outside of brain parenchyma Clear Demarcation Since the arachnoid cyst is bound by arachnoid membrane, it has well-defined margins CSF collection contained within a split arachnoid membrane that occurs during embryological development (primary) Cerebrospinal Fluid (CSF) collection within arachnoid membrane adhesions following trauma, infection, inflammation or surgery (secondary) Arachnoid cyst (fluid-filled sac) formation within the layers of the arachnoid membrane, outside of brain parenchyma (for full pathogenesis, see Calgary Guide slide Arachnoid Cysts: Pathogenesis and clinical findings) Use Diffusion Weighted Imaging (DWI) and Fluid-Attenuated Inversion Recovery (FLAIR) to distinguish from other cysts Isointense to CSF on T1 and T2 Arachnoid cyst contents should appear isointense to CSF on each MR sequence, including diffusion-weighted imaging Axial T2 MRI Head. Clearly demarcated hyperintense (bright) arachnoid cyst is seen (red arrows) Axial T1 MRI Head. Clearly demarcated hypointense (dark) arachnoid cyst is seen (red arrows) FLAIR allows for suppression of free water signal to enhance fluid with ↑ protein concentration Arachnoid cysts contain CSF-like fluid with very little to no protein Complete suppression on FLAIR Cysts are mostly fluid and contains no protein, so it is suppressed and appears darker in FLAIR images. Axial FLAIR MRI Head. Hypointense cyst is seen on FLAIR (red arrows), showing low protein content in CSF-like fluid inside arachnoid cyst DWI measures water diffusion in different directions and whether there is restriction on the direction of flow Fluid within the cyst can flow freely, with no restriction on the direction of movement Non-restricted diffusion There is no directional restriction on flow within the cyst (unrestricted diffusion), so it appears dark on DWI. Axial DWI MRI Head. Hypointense cyst is seen on DWI (red arrows), showing unrestricted diffusion within arachnoid cyst Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Jan 20, 2024 on www.thecalgaryguide.com

Arachnoid Cysts Pathogenesis and clinical findings

Arachnoid Cysts: Pathogenesis and clinical findings Authors: George S. Tadros Reviewers: Yvette Ysabel Yao Shahab Marzoughi Gary Michael Klein* * MD at time of publication Failure in the embryological duplication or division of the arachnoid membrane Cerebrospinal fluid (CSF)-like fluid is trapped within the erroneous membrane Formation of a primary, congenital arachnoid cyst (most common cause) Head trauma, intracranial hemorrhage, or infection Inflammation and deposition of cellular matrix Adhesion of the arachnoid membrane CSF accumulates in the subarachnoid space (space between the arachnoid mater and pia mater) Formation of a secondary arachnoid cyst (less common) Cyst remains stable in size and does not expand (most common) Patients are asymptomatic Arachnoid cyst is diagnosed incidentally on unrelated neuroimaging (see Calgary Guide slide Arachnoid Cysts: Findings on MRI) Arachnoid Cyst Cyst grows in size and expands (rare but more common in children under four years of age) Cyst exerts pressure on other structures (mass effect) Suprasellar region Cyst ruptures into the subdural space (rare) CSF-like fluid accumulates in the subdural space Subdural hygroma (collection of non-bloody CSF) Intracranial hypertension (↑ intracranial pressure) Generalized symptoms Middle fossa Compression and irritation of the temporal cortex Seizures Focal symptoms depending on cyst location Cerebellopontine angle Compression of vestibulocochlear nerve (Cranial Nerve VIII) Compression and interruption of cochlear blood supply Cyst presses on the third ventricle and aqueduct buildup of CSF in the ventricles Obstructive hydrocephalus Cyst presses on the optic chiasm, hypothalamus, and pituitary Visual impairments and endocrinopathies Headache (most common) Vomiting Nausea Progressive hearing loss Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Jan 25, 2024 on www.thecalgaryguide.com

Avascular Necrosis AVN of the Femoral Head Findings on MRI

Avascular Necrosis (AVN) of the Femoral Head: Findings on MRI Traumatic or atraumatic disruption of blood supply to the proximal femur (for full pathogenesis, see Calgary Guide slide Avascular Necrosis: Pathogenesis and clinical findings) Ischemia of the femoral head (usually unilateral for traumatic and bilateral for non-traumatic) Prolonged anoxia (total oxygen deprivation) within the femoral head Cell death (necrosis) of osteocytes and marrow cells in the femoral head, forming a focal lesion (sequestrum) Histiocytes and giant cells (immune cells) aggregate around the sequestrum, forming a “reactive zone” around the periphery of the sequestrum Apoptotic osteocytes in the anoxic reactive zone cannot be phagocytosed leading to dysregulated bone remodeling and osteosclerosis (hardening of bone and ↑ bone mineralization and density due to ↓ resorption and ↑ bone formation) Femoral head becomes progressively weaker while the mechanical load on it remains the same Progressive femoral head/subchondral bone collapse Osteoarthritis Areas with ↑ fluid content appear darker on T1w images Areas with ↑ fluid content appear brighter on T2w images Areas with ↑ bone density and ↓ fat content appear darker on T1w images Areas with ↑ bone density and ↓ fat content appear darker on T2w images Basic MRI Physiology Edema and inflammation increases fluid content Sclerotic areas have ↑ bone density and thus ↓ fat content Location of Signs Inflamed reactive zones are darker on T1w images Inflamed reactive zones are brighter on T2w images Sclerotic areas are darker on both T1w and T2w images Authors: George S. Tadros Reviewers: Matthew Hobart, Mao Ding Shahab Marzoughi David Cornell* * MD at time of publication T1w Signs on both T1-weighted and T2-weighted images are most commonly seen on the superior anterolateral aspect of the femoral head Single dark band on T1-weighted MRI A single band-like crescentic lesion of low signal intensity is seen on T1-weighted MRI images (white arrows). This band represents the edematous reactive zone between the necrotic and normal tissue, and typically extends to the subchondral plate Double Line Sign on T2-weighted fat-saturated MRI An outer distal low signal intensity line is seen (white arrows) representing reactive bone sclerosis Image source: radiologymasterclass T2w An inner proximal high signal intensity line is also seen (red arrows) representing vascular and repair tissue at the periphery of the sequestrum Image source: radiologymasterclass Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Jan 27, 2024 on www.thecalgaryguide.com

Bacterial Infections from Transfusion

Bacterial Infections from Transfusion: Signs and Symptoms Caused by bacterial contamination of any blood product, most commonly platelets due to room-temperature storage Bacteria enters bloodstream directly through transfusion Immune cells (ex. macrophages, dendritic cells, monocytes, neutrophils) recognize bacteria Immune cells release pyrogens (either bacterial components or signalling molecules) upon recognition Pyrogens bind to receptors on the hypothalamus Hypothalamus ↑ body temperature set point Body generates and conserves heat to reach set point Immune cells release pro- inflammatory cytokines (messenger protein) Cytokines activate sympathetic nervous system via hypothalamus Adrenal glands release stress hormones (epinephrine and norepinephrine) into bloodstream Stress hormones bind to receptors on cardiomyocytes (heart muscle cells) ↑ Heart contractility ↑ Heart rate Cytokines circulate throughout the body Cytokines interact with endothelial cells of the blood vessels ↑ Nitric oxide production Relaxes smooth muscle cells of blood vessel walls Vasodilation (↑ blood vessel diameter) Hypotension Systemic inflammation Stimulate nerve endings in muscles Stimulate nerve endings in gastrointestinal tract’s lining Blood brain barrier’s integrity is compromised Nitric oxide reacts with oxygen to form reactive nitrogen species Tissue damage Fatigue Weakness Muscle aches Nausea and vomiting Immune and inflammatory cells enter the brain Authors: Arzina Jaffer Kayleigh Yang Reviewers: Nimaya De Silva Raafi Ali Michelle J. Chen Yan Yu* Kareem Jamani* * MD at time of publication Inflammation in the brain Activates pain processing centers in the brain Headache Damages neurons and disrupts cell communication Confusion and altered mental state Shivering Fever Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published January 30, 2024 on www.thecalgaryguide.com

Acute Wound Healing

↓ Blood supply and oxygenation to local skin tissue Ischemia Degradation of intact skin Abrasion (damage by scrape/rub) Puncture (small piercing caused by sharp object) Acute injury to the skin Crush (damage by compression) Acute Wound Healing: Pathogenesis and clinical findings Author: Amanda Eslinger Mina Youakim Reviewers: Heena Singh Shahab Marzoughi Yan Yu Laurie Parsons* * MD at time of publication 8 – 365+ days post-injury Remodeling (↓ blood vessels & organized collagen) Extensively cross-linked type 1 collagen replaces the disorganized collagen laid down in the proliferative phase ↑ Protein content in collagen Scarring (fibrotic tissue replaces previously healthy tissue) Disruption of structure and function of dermis, epidermis and subdermal tissues Subendothelial and endothelial damage activates the coagulation pathway Formation of a platelet plug Bleeding is slowed or stopped by hemostatic plug (hemostasis) Clot unifies wound edges 0 – 7 days post-injury Inflammation (In disrupted skin layers) 4 - 14 days post-injury Proliferation of collagen, extracellular matrix & blood vessels TGF-β attracts fibroblasts to the site of the wound Fibroblast & macrophage stimulate tissue growth & angiogenesis which replaces hemostatic plug Scabbing (protective crust overlying damaged tissue) Re-epithelialization beneath the scab sloughs it off Healing (newly replaced tissue replaces damaged one) In response to irritant, mast cells release histamine Complement activation causing nearby endothelial cells to release prostaglandins Vasodilation occurs around the wound area Localized ↑ vascular supply (reception of blood and fluid from vessels) ↑ Hydrostatic pressure forces fluid from vessels into surrounding tissue Edema (swelling from fluid buildup) Erythema (redness) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications First Published Sept 19, 2013; updated Jan 30, 2024 on www.thecalgaryguide.com

Acute Otitis Externa Complications

Acute Otitis Externa (Swimmer’s Ear): Complications Acute Otitis Externa (AOE) Authors: Charmaine Szalay-Anderson Vaneeza Moosa Reviewers: Shayan Hemmati Shahab Marzoughi Ben Campbell Justin Lui* * MD at time of publication Spread to subcutaneous tissue Chronic otitis externa (>6 weeks) Chronic inflammation of the outer ear Fibroblast activation for collagen and extracellular matrix components production for tissue repair Excess accumulation of tissue Ear canal fibrosis (thickening) Ear canal stenosis (narrowing) Damage/obstruction to ear canal structures with impaired fluid drainage & pressure buildup Inflammation of the outer ear Recurrent or non-resolving acute otitis externa Dissemination of infection Spread to connective tissue and cartilage Perichondritis (inflammation of ear cartilage) Spread of Pseudomonas aeruginosa in an immunocompromised host or due to antibiotic resistance Rapid infectious spread through soft tissue to mastoid and/or temporal bone Malignant (necrotizing) otitis externa *can be life threatening Inflammation of connective tissue and bony structures Spread to tympanic membrane Myringitis (inflammation of tympanic membrane) Swelling and thinning of tissue Tympanic membrane perforation (tear) Immune reaction with inflammation Dead white blood cell, bacteria & tissue debris accumulation in the ear canal Pus formation with purulent otorrhea (discharge from ear) Localized pus accumulation Abscess Ear canal blockage Periauricular/ pinna (outer ear) cellulitis Facial cellulitis Erosion of temporal bone decreasing bony sound conduction Permanent conductive hearing loss Direct toxicity of pathogens to surrounding nerves Cranial nerve (CN) VII (facial) palsy (+/- CN X, XI, XII) Out-of- proportion primary otalgia (ear pain) Sensation of fullness in the ear Temporary hearing loss Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Dec 4, 2022; updated Feb 7, 2024 on www.thecalgaryguide.com

Infective endocarditis

Infective Endocarditis: Pathogenesis, complications, and clinical findings Subacute Endocarditis Pre-existing valvular stenosis or regurgitation Non-laminar flow across valve damages valve endothelium A sterile thrombus forms Thrombus forms on the surface of a cardiac valve Acute Endocarditis Poor dental hygiene/recent dental procedure Invasive procedure/indwelling device Positive blood cultures Activation of immune system Valve Trauma Invading bacterium Intravenous (IV) drug use (mostly causes right sided endocarditis) Bacteria enter the bloodstream (bacteremia) In subacute cases, valvular abnormality usually present beforehand In all cases, vegetation forms on affected valve Immune complex deposit in kidney Immune complexes cause vasculitis in retinal vessels Immune complexes deposit subcutaneously ↓ Blood flow to organs perfused by the obstructed arteries Valve endothelium is damaged Bacteria adhere to thrombi on the cardiac valve endothelium Infective Endocarditis Infection of the thrombus typically produces a vegetation on the flow surface of a valve Immune complexes (complexes of antibody bound to antigen) form secondary to infection Generalized immune response Malaise Chills Fever (> 38°C) Author: Sean Spence George S. Tadros Reviewers: Yan Yu Jason Baserman Danny Guo Steve Vaughan* *MD at time of publication Parts of vegetation embolize systemically, obstructing arteries Infection destroys infected valve Smaller emboli block smaller vessels on hands/feet Microinfarctions Mitral regurgitation, Aortic stenosis, Aortic insufficiency (Valve involvement: Mitral > Aortic > Tricuspid) Vegetation seen on ultrasound/echocardiogram Damage to Glomerulonephritis glomeruli (Inflammation of glomeruli) Roth’s spots (retinal hemorrhages with pale centers due to coagulated fibrin) Osler nodes (tender, raised, red lesions found on the hands and feet) Organ infarction (tissue death) Splinter hemorrhages (small red streaks under nails) Janeway lesions (non-tender, red macules/nodules on palms/soles – only a few millimeters wide) Regurgitation (blood leaks back through the insufficient valve despite it being closed) Valve unable to fulfill normal functions (valve insufficiency) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Aug 20, 2013, updated Feb 24, 2024 on www.thecalgaryguide.com

Onychomycosis

Dermatophyte Onychomycosis: Pathogenesis and clinical findings Authors: Holly Zahary Loreman Reviewers: Mina Youakim Elise Hansen Shahab Marzoughi Jodi Hardin* * MD at time of publication Host Risk Factors Environmental Risk Factors Immuno- compromised ↓ Immune response to infection Older age Peripheral vascular disease Reduced blood circulation Diabetes Pre-existing nail dystrophy Previous nail trauma Integrity of nail unit is compromised Micro- traumatic pressure on nail Dark, warm shoe environment Optimal conditions for fugal growth Exposure to tinea pedis or onychomycosis Direct spread of infection to nail unit High blood sugar favoring infection Dermatophytes invade corneocytes on stratum corneum, the uppermost non- living layer of keratinized skin Compromise/breaking of hyponychial seal or cuticle (connection between hyponychium and nail plate) Proximal Subungual White Superficial Tinea infection (e.g. Tinea Pedis, Corporis, Capitis) Infection spreads to distal hyponychial space Dermatophytes colonize local tissue in nail plate and nail bed Dermatophytes feed on keratinized tissue General Symptoms (All Subtypes) Spongiosis (Intercellular edema) Acanthosis (Thickening of stratum spinosum layer of epidermis) Hyperkeratosis (Thickening of stratum corneum In effort to rid infection) Papillomatosis (Projections of dermal papillae) Secondary damage to nail matrix Loss of nail Keratinocytes produce an acute, low-grade inflammatory cytokine response Onychomycosis Dermatophytic infection of the nail bed Inflammation promotes ↑ fluid to tissues for ↑ immune cell delivery Widespread inflammation thickens parts of the epidermis in efforts to shed the infection Inflammation and epidermal hyperplasia (↑ growth of cells) influence local dermal papillae (group of cells just beneath the hair follicle) to proliferate and project above the skin Distal Subungual Superinfecting bacteria or other fungi proliferate beneath the compromised nail imparting a yellowish appearance Distal Subungual Subtype (Thick yellow nails, keratin and debris accumulate distally underneath nail plate) Dermatophytes invade the proximal end of the nail plate Dermatophytes penetrate through the cuticle to the newly forming nail plate moving distally Proximal Subungual Subtype (Whitish discolouration of nail plate that begins proximally and moves distally, indicative of immunosuppression) Fungi predominantly invade various areas of the superficial nail plate layers eventually joining together White Superficial Subtype (Chalky white scale that spreads slowly beneath nail plate, well-defined “white islands” that coalesce as disease progresses) The entirety of the nail plate is infected by the dermatophytes Widespread inflammation thickens the nail plate as well as beneath the nail (subungual hyperkeratosis) in efforts to shed the infection Total Dystrophic Subtype (End-stage nail disease, entire nail becomes thick and dystrophic) Local spread of infection Dermatophytes spread causing cracks in the skin deeper into toe Abnormal keratinization in hyponychium Keratin accumulates between nail plate and hyponychium Fissure (splits in the skin) Bacteria enters lymphatics and bloodstream Cellulitis Sepsis Onycholysis (nail plate separates from nail bed) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Mar 13, 2024 on www.thecalgaryguide.com Dermatophyte Onychomycosis: Pathogenesis and clinical findings Authors: Holly Zahary Loreman Reviewers: Mina Youakim Elise Hansen Shahab Marzoughi Jodi Hardin* * MD at time of publication Host Risk Factors Environmental Risk Factors Immuno- compromised ↓ Immune response to infection Older age Peripheral vascular disease Reduced blood circulation Diabetes Pre-existing nail dystrophy Previous nail trauma Integrity of nail unit is compromised Micro- traumatic pressure on nail Dark, warm shoe environment Optimal conditions for fugal growth Exposure to tinea pedis or onychomycosis Direct spread of infection to nail unit High blood sugar favoring infection Dermatophytes invade corneocytes on stratum corneum, the uppermost non-living layer of keratinized skin Compromise/breaking of hyponychial seal or cuticle (connection between hyponychium and nail plate) Proximal Subungual White Superficial Distal Subungual Superinfecting bacteria or other fungi proliferate beneath the compromised nail imparting a yellowish appearance Distal Subungual Subtype (Thick yellow nails, keratin and debris accumulate distally underneath nail plate) Infection spreads to distal hyponychial space Dermatophytes colonize local tissue in nail plate and nail bed Dermatophytes feed on keratinized tissue Keratinocytes produce an acute, low-grade inflammatory cytokine response Onychomycosis Dermatophytic infection of the nail bed Inflammation promotes ↑ fluid to tissues for ↑ immune cell delivery Widespread inflammation thickens parts of the epidermis in efforts to shed the infection Inflammation and epidermal hyperplasia (↑ growth of cells) influence local dermal papillae (group of cells just beneath the hair follicle) to proliferate and project above the skin General Symptoms (All Subtypes) Spongiosis (Intercellular edema) Acanthosis (Thickening of stratum spinosum layer of epidermis) Hyperkeratosis (Thickening of stratum corneum In effort to rid infection) Papillomatosis (Projections of dermal papillae) Secondary damage to nail matrix Loss of nail Tinea infection (e.g. Tinea Pedis, Corporis, Capitis) Dermatophytes invade the proximal end of the nail plate Dermatophytes penetrate through the cuticle to the newly forming nail plate moving distally Proximal Subungual Subtype (Whitish discolouration of nail plate that begins proximally and moves distally, indicative of immunosuppression) Fungi predominantly invade various areas of the superficial nail plate layers eventually joining together White Superficial Subtype (Chalky white scale that spreads slowly beneath nail plate, well-defined “white islands” that coalesce as disease progresses) The entirety of the nail plate is infected by the dermatophytes Widespread inflammation thickens the nail plate as well as beneath the nail (subungual hyperkeratosis) in efforts to shed the infection Total Dystrophic Subtype (End-stage nail disease, entire nail becomes thick and dystrophic) Dermatophytes spread deeper into toe Bacteria enters lymphatics and bloodstream Abnormal keratinization in hyponychium Keratin accumulates between nail plate and hyponychium Local spread of infection causing cracks in the skin Fissure (splits in the skin) Cellulitis Sepsis Onycholysis (nail plate separates from nail bed) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published MONTH, DAY, YEAR on www.thecalgaryguide.com Dermatophyte Onychomycosis: Pathogenesis and clinical findings Authors: Holly Zahary Loreman Reviewers: Mina Youakim Elise Hansen Shahab Marzoughi Jodi Hardin* * MD at time of publication Host Risk Factors Environmental Risk Factors Immuno- Older compromised age ↓ Immune response to infection Peripheral vascular disease Reduced blood circulation Diabetes Pre-existing nail dystrophy Previous nail trauma Integrity of nail unit is compromised Micro- traumatic pressure on nail Dark, warm shoe environment Optimal conditions for fugal growth Exposure to tinea pedis or onychomycosis Direct spread of infection to nail unit High blood sugar favoring infection Dermatophytes invade corneocytes on stratum corneum, the uppermost non-living layer of keratinized skin Compromise/breaking of hyponychial seal or cuticle (connection between hyponychium and nail plate) Tinea infection (e.g. Tinea Pedis, Corporis, Capitis) Infection spreads to distal hyponychial space Dermatophytes colonize local tissue in nail plate and nail bed Dermatophytes feed on keratinized tissue Keratinocytes produce an acute, low-grade inflammatory cytokine response Onychomycosis Dermatophytic infection of the nail bed General Symptoms (All Subtypes) Spongiosis (Intercellular edema) Acanthosis (Thickening of stratum spinosum layer of epidermis) Papillomatosis (Projections of dermal papillae) Hyperkeratosis (Thickening of stratum corneum In effort to rid infection) Secondary damage to nail matrix Loss of nail Proximal Subungual White Superficial Distal Subungual Distal Subungual Subtype (Thick yellow nails, keratin and debris accumulate distally underneath nail plate) Proximal Subungual Subtype (Whitish discolouration of nail plate that begins proximally and moves distally, indicative of immunosuppression) White Superficial Subtype (Chalky white scale that spreads slowly beneath nail plate, well-defined “white islands” that coalesce as disease progresses) Total Dystrophic Subtype (End-stage nail disease, entire nail becomes thick and dystrophic) Local spread of infection causing cracks in the skin Dermatophytes spread deeper into toe Abnormal keratinization in hyponychium Keratin accumulates between nail plate and hyponychium Onycholysis (nail plate separates from nail bed) Fissure (splits in the skin) Bacteria enters lymphatics and bloodstream Cellulitis Sepsis Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Legend: Published MONTH, DAY, YEAR on www.thecalgaryguide.com Dermatophyte Onychomycosis: Pathogenesis and clinical findings Authors: Holly Zahary Loreman Reviewers: Mina Youakim Elise Hansen Shahab Marzoughi Jodi Hardin* * MD at time of publication Host Risk Factors Environmental Risk Factors Immuno- Older compromised age ↓ Immune response to infection Peripheral vascular disease Reduced blood circulation Diabetes Pre-existing nail dystrophy Previous nail trauma Integrity of nail unit is compromised Micro- traumatic pressure on nail Dark, warm shoe environment Optimal conditions for fugal growth Exposure to tinea pedis or onychomycosis Direct spread of infection to nail unit High blood sugar favoring infection Dermatophytes invade corneocytes on stratum corneum, the uppermost non-living layer of keratinized skin Compromise/breaking of hyponychial seal or cuticle (connection between hyponychium and nail plate) Tinea infection (e.g. Tinea Pedis, Corporis, Capitis) Infection spreads to distal hyponychial space Dermatophytes colonize local tissue in nail plate and nail bed Dermatophytes feed on keratinized tissue Keratinocytes produce an acute, low-grade inflammatory cytokine response Onychomycosis Dermatophytic infection of the nail bed Proximal Subungual White Superficial General Symptoms (All Subtypes) Spongiosis (Intercellular edema) Acanthosis (Thickening of stratum spinosum layer of epidermis) Papillomatosis (Projections of dermal papillae) Hyperkeratosis (Thickening of stratum corneum In effort to rid infection) Secondary damage to nail matrix Loss of nail Distal Subungual Distal Subungual Subtype (Thick yellow nails, keratin and debris accumulate distally underneath nail plate) Proximal Subungual Subtype (Whitish discolouration of nail plate that begins proximally and moves distally, indicative of immunosuppression) White Superficial Subtype (Chalky white scale that spreads slowly beneath nail plate, well- defined “white islands” that coalesce as disease progresses) Total Dystrophic Subtype (End-stage nail disease, entire nail becomes thick and dystrophic) Local spread of infection causing cracks in the skin Dermatophytes spread deeper into toe Abnormal keratinization in hyponychium Keratin accumulates between nail plate and hyponychium Onycholysis (nail plate separates from nail bed) Bacteria enters lymphatics and bloodstream Fissure (splits in the skin) Cellulitis Sepsis Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Legend: Published MONTH, DAY, YEAR on www.thecalgaryguide.com Dermatophyte Onychomycosis (Tinea Unguium): Pathogenesis, clinical findings, Authors: Holly Zahary Loreman Reviewers: Elise Hansen Name Name* * MD at time of publication and complications Host Risk Factors Environmental Risk Factors Immuno- compromised ↓ immune response to infection Older age Peripheral vascular disease Diabetes Pre-existing nail dystrophy Previous Nail Trauma Integrity of nail unit is compromised Micro-traumatic pressure on nail Dark, warm shoe environment Optimal conditions for fugal growth Exposure to tinea pedis or onychomycosis Direct spread of infection to nail unit Reduced blood circulation High blood sugar, favoring infection Tinea pedis infection (see ‘Tinea Capitis, Tinea Corporis, and Tinea Pedis’) Infection spreads to distal hyponychial space Dermatophytes colonize local tissue in nail plate and nail bed Dermatophytes feed on keratinized tissue Proximal Subungual White Superficial Dermatophytes invade corneocytes on stratum corneum, the uppermost non-living layer of keratinized skin Compromise/breaking of hyponychial seal or cuticle (connection between hyponychium and nail plate) Keratinocytes produce an acute, low-grade inflammatory cytokine response Onychomycosis (Tinea Unguium) (dermatophytic infection of the nail bed) Distal Subungual General Symptoms (All Subtypes) Spongiosis Intercellular edema Acanthosis Thickening of stratum spinosum layer of epidermis Papillomatosis Projections of dermal papillae Hyperkeratosis Thickening of stratum corneum In effort to rid infection Secondary damage to nail matrix Loss of nail Distal Subungual Subtype Thick yellow nails, keratin and debris accumulate distally underneath nail plate Proximal Subungual Subtype Whitish discolouration of nail plate that begins proximally and moves distally, indicative of immunosuppression White Superficial Subtype Chalky white scale that spreads slowly beneath nail plate, well-defined “white islands” that coalesce as disease progresses Total Dystrophic Subtype End-stage nail disease, entire nail becomes thick and dystrophic Local spread of infection causing cracks in the skin Dermatophytes spread deeper into toe Abnormal keratinization in hyponychium Keratin accumulates between nail plate and hyponychium Onycholysis (nail plate separates from nail bed) Tissue Damage Cellulitis Sepsis Bacteria enters lymphatics and bloodstream Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Legend: Published MONTH, DAY, YEAR on www.thecalgaryguide.com

Neonatal Necrotising Enterocolitis in Premature Neonates

Neonatal Necrotising Enterocolitis (NEC) in Premature Neonates: Pathogenesis and clinical findings Prematurity risk factors ↓ Intestinal motility ↑ Intestinal stasis allows bacteria more time to proliferate Bacterial overgrowth in gut ↓ Goblet cells in intestinal epithelium ↓ Intestinal mucus layer production leads to impaired mechanical defense against pathogenic bacteria Immature tight junctions in intestinal epithelium ↑ Permeability of intestinal epithelial barrier ↑ Toll-like receptor 4 (TLR4) expression on intestinal epithelial cells Aberrant bacterial colonization of gut Impaired gut barrier allows for ↑ bacterial translocation across intestinal epithelium TLR4 on intestinal mesentery endothelial cells bind lipopolysaccharides (LPS) on Gram-negative gut bacteria Immune cells release proinflammatory mediators (TNF, IL-12, IL-18) Cytokines mediate ↑ enterocyte apoptosis (including enteric stem cells) and ↓ enterocyte proliferation Intestinal mucosa healing is impaired, leading to local inflammation & injury TLR4 on intestinal epithelial cells binds LPS from Gram-negative gut bacteria Authors: Rachel Bethune Naima Riaz Reviewers: Nicola Adderley Michelle J. Chen Kamran Yusuf* Jean Mah* * MD at time of publication Endothelial nitric oxide synthase expression is reduced Vasoconstriction from ↓ NO reduces blood flow to intestines Prolonged ↓ in O2 perfusion results in irreversible intestinal mucosal cell death (necrosis) Gas escapes into abdominal cavity Leakage of intestinal contents irritates parietal peritoneum Bacteria enter bloodstream Pneumo- peritoneum Abdominal distention Peritonitis Sepsis Blood from tissue damage mixes with intestinal contents Bloody stool Intestinal sensory neurons detect damage and send signals to medullary vomiting centre Bilious vomiting Damaged intestinal cells are unable to absorb nutrients Short gut syndrome Persistent intestinal mucosal injury creates penetrating lesions through intestinal wall Intestinal perforation Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published May 6, 2019; updated Mar 21, 2024 on www.thecalgaryguide.com

Lichen Sclerosus

Lichen Sclerosus (genital manifestation): Pathogenesis and clinical findings Authors: Mina Youakim Reviewers: Elise Hansen Sunawer Aujla Shahab Marzoughi Jori Hardin* * MD at time of publication Histamine receptor binding stimulates sensory nerve endings Pruritus (itching) Unknown triggers Genetic predisposition (HLA-DQ7 and HLA-DR12) Chronic inflammation (i.e. chronic infection, chronic toxin exposure) and trauma Medications (e.g. carbamazepine, pembrolizumab, nivolumab, ipilimumab) ↑ Activation of CD4+ and CD8+ T cells released from macrophages (white blood cell) in the perineum and genital skin tissue infiltrate into the dermal-epidermal junction T-cells proliferate in a horizontal linear formation Pro-inflammatory response activation Fibroblasts (contributes to the formation of connective tissue) proliferate and persist producing altered collagen under the epidermis Collagen deposits and hyalinizes (transforms into acellular translucent material) beneath the epidermal layer Sclerotic plaques (localized areas of thickened skin) T cells release of pro-inflammatory cytokines (interleukins and transforming growth factor β) ↑ Oxidative stress and cell damage Progressive basal layer degeneration thins the overall skin thickness Mast cells respond to increased need for immune cell flow to area Nitric oxide is released when histamine binds to vascular receptors Localized area appears red Erythema (reddening of the skin) Erosion/ulceration Skin fissures (linear cleavage of skin) Localized histamine release Nitric oxide induces localized vasodilation (↑ blood flow) Normal Skin Lichen Sclerosus Epidermal layer Basal layer Dermal-Epidermal Junction Dermal layer Hypopigmented patches (localized, pale areas of skin) Epidermal atrophy (crinkling paper-type skin appearance) Thinned skin is weakened and prone to physical stress or trauma ↑ fluid in the extracellular space due to capillary leakage from ↑ blood flow Superficial dermal edema (swelling) Fibrotic tissue deposition following healing of damaged tissue Atrophic Epidermal layer Hyalinized collagen deposits Basal layer degeneration Band of T-cell infiltrate Dermal layer Scarring Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Mar 25, 2024 on www.thecalgaryguide.com Lichen Sclerosus (genital manifestation): Pathogenesis and clinical findings Authors: Mina Youakim Reviewers: Elise Hansen Sunawer Aujla Shahab Marzoughi Jori Hardin* * MD at time of publication Histamine receptor binding stimulates sensory nerve endings Pruritus (itching) Unknown triggers Genetic predisposition (HLA-DQ7 and HLA-DR12) Chronic inflammation (i.e. chronic infection, chronic toxin exposure) and trauma Medications (e.g. carbamazepine, pembrolizumab, nivolumab, ipilimumab) ↑ Activation of CD4+ and CD8+ T cells released from macrophages (white blood cell) in the perineum and genital skin tissue infiltrate into the dermal-epidermal junction T-cells proliferate in a horizontal linear formation Pro-inflammatory response activation Fibroblasts (contributes to the formation of connective tissue) proliferate and persist producing altered collagen under the epidermis Collagen deposits and hyalinizes (transforms into acellular translucent material) beneath the epidermal layer Sclerotic plaques (localized areas of thickened skin) T cells release of pro-inflammatory cytokines (interleukins and transforming growth factor β) ↑ Oxidative stress and cell damage Mast cells respond to increased need for immune cell flow to area Nitric oxide is released when histamine binds to vascular receptors ↑ fluid in the extracellular space due to capillary leakage from ↑ blood flow Superficial dermal edema (swelling) Epidermal atrophy (crinkling paper- type skin appearance) Thinned skin is weakened and prone to physical stress or trauma Localized histamine release Nitric oxide induces localized vasodilation (↑ blood flow) Localized area appears red Erythema (reddening of the skin) Erosion/ulceration Skin fissures (linear cleavage of skin) Normal Skin Lichen Sclerosus Epidermal layer Basal layer Dermal-Epidermal Junction Dermal layer Atrophic Epidermal layer Hyalinized collagen deposits Basal layer degeneration Band of T-cell infiltrate Dermal layer Progressive basal layer degeneration thins the overall skin thickness Hypopigmented patches (localized, pale areas of skin) Fibrotic tissue deposition following healing of damaged tissue Scarring Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published MONTH, DAY, YEAR on www.thecalgaryguide.com Chronic inflammation (i.e. chronic Reviewers: Dermal layer Unknown triggers Genetic predisposition (HLA-DQ7 and HLA-DR12) infection, chronic toxin exposure) and trauma Medications (e.g. carbamazepine, pembrolizumab, nivolumab, ipilimumab) Elise Hansen Sunawer Aujla Shahab Marzoughi Jori Hardin* * MD at time of publication ↑ Activation of CD4+ and CD8+ T cells released from macrophages (white blood cell) in the perineum and genital skin tissue infiltrate into the dermal-epidermal junction T-cells proliferate in a horizontal linear formation Pro-inflammatory response activation ↑ Expression of MicroRNA-155 (enhances pro-inflammatory response and ↓ expression of tumor suppression genes) Fibroblasts (contributes to the formation of connective tissue) proliferate and persist producing altered collagen Collagen deposits and hyalinizes (transforms into acellular translucent material) beneath the epidermal layer Sclerotic plaques (localized areas of thickened skin) T cells release of pro-inflammatory cytokines (interleukins and transforming growth factor β) ↑ Oxidative stress and cell damage Mast cells respond to increased need for immune cell flow to area Nitric oxide is released when histamine binds to vascular receptors ↑ fluid in the extracellular space due to capillary leakage from ↑ blood flow Superficial dermal edema (swelling) Epidermal atrophy (crinkling paper- type skin appearance) Thinned skin is weakened and prone to physical stress or trauma Lichen Sclerosus Localized histamine release Nitric oxide induces localized vasodilation (↑ blood flow) Localized area appears red Erythema (reddening of the skin) Erosion/ulceration Skin fissures (linear cleavage of skin) Atrophic Epidermal layer Hyalinized collagen deposits Basal layer degeneration Band of T-cell infiltrate Histamine receptor binding stimulates sensory nerve endings Pruritus (itching) Normal Skin Progressive basal layer degeneration thins the overall skin thickness Hypopigmented patches (localized, pale areas of skin) Epidermal layer Basal layer Dermal-Epidermal Junction Fibrotic tissue deposition following healing of damaged tissue Scarring Chronic inflammation (i.e. chronic Reviewers: Dermal layer Unknown triggers Genetic predisposition (HLA-DQ7 and HLA-DR12) infection, chronic toxin exposure) and trauma Medications (e.g. carbamazepine, pembrolizumab, nivolumab, ipilimumab) Elise Hansen Sunawer Aujla Shahab Marzoughi Jori Hardin* * MD at time of publication ↑ Activation of CD4+ and CD8+ T cells released from macrophages in the perineum and genital skin tissue infiltrate into the dermal-epidermal junction T-cells proliferate in a horizontal linear formation Pro-inflammatory response activation ↑ Expression of MicroRNA-155 (short segment of RNA which enhances pro- inflammatory response and ↓ expression of tumor suppression genes) Fibroblasts proliferate and persist producing altered collagen Collagen deposits and hyalinizes (transforms into acellular translucent material) beneath the epidermal layer Sclerotic plaques (localized areas of thickened skin) T cells release of pro-inflammatory cytokines (interleukins and transforming growth factor β) ↑ Oxidative stress and cell damage Progressive basal layer degeneration thins the overall skin thickness Hypopigmented patches (localized, pale areas of skin) Epidermal layer Basal layer Dermal-Epidermal Junction Mast cells respond to increased need for immune cell flow to area Nitric oxide is released when histamine binds to vascular receptors Superficial dermal edema (swelling) Epidermal atrophy (crinkling paper- type skin appearance) Localized histamine release Nitric oxide induces localized vasodilation (↑ blood flow) Localized area appears red Erythema (reddening of the skin) Histamine receptor binding stimulates sensory nerve endings Pruritus (itching) Normal Skin Lichen Sclerosus Skin fissures (linear cleavage of skin) Erosion/ulceration Fibrotic tissue deposition following healing of damaged tissue Scarring Atrophic Epidermal layer Hyalinized collagen deposits Basal layer degeneration Band of T-cell infiltrate Reviewers: Dermal layer Unknown triggers Genetic predisposition (HLA-DQ7 and HLA-DR12) Chronic inflammation (i.e. chronic infection, chronic toxin exposure) and trauma Medications (e.g. carbamazepine, pembrolizumab, nivolumab, ipilimumab) Elise Hansen Sunawer Aujla Shahab Marzoughi Jori Hardin* * MD at time of publication ↑ Activation and infiltration of CD4+ and CD8+ T cells into the dermal-epidermal junction T-cells proliferate in a band (horizontal linear) formation Pro-inflammatory response activation ↑ Expression of MicroRNA-155 (short segment of RNA which enhances pro-inflammatory response and ↓ expression of tumor suppression genes) Fibroblasts proliferate and persist producing altered collagen Collagen deposits and hyalinizes (transforms into acellular translucent material) beneath the epidermal layer Sclerotic plaques (localized areas of thickened skin) T cells release of pro-inflammatory cytokines (interleukins and transforming growth factor β) ↑ Oxidative stress and cell damage Progressive basal layer degeneration thins the epidermis Hypopigmented patches (localized, pale areas of skin) Epidermal layer Basal layer Dermal-Epidermal Junction Mast cells respond to increased need for immune cell flow to area Nitric oxide is released when histamine binds to vascular receptors Superficial dermal edema (swelling) Epidermal atrophy (crinkling paper- type skin appearance) Localized histamine release Histamine receptor binding stimulates sensory nerve endings Pruritus (itching) Skin fissures (linear cleavage of skin) Nitric oxide induces localized vasodilation (↑ blood flow) Localized area appears red Erythema (reddening of the skin) Scarring Atrophic Epidermal layer Hyalinized collagen deposits Basal layer degeneration Band of T-cell infiltrate Erosion/ulceration Fibrotic tissue deposition following healing of damaged tissue Normal Skin Lichen Sclerosus Chronic inflammation (i.e. chronic Elise Hansen Unknown triggers Genetic predisposition infection, chronic toxin exposure) Medications (e.g. carbamazepine, (HLA-DQ7 and HLA-DR12) and trauma pembrolizumab, nivolumab, ipilimumab) ↑ Activation and infiltration of CD4+ and CD8+ T cells into the dermal-epidermal junction Sunawer Aujla Shahab Marzoughi Name Name* * MD at time of publication T-cells proliferate in a band (horizontal linear) formation Pro-inflammatory response activation (increase in pro-inflammatory cytokines such as Interleukins 1-alpha and 1-beta) ↑ Expression of MicroRNA-155 (short segment of RNA which enhances pro-inflammatory response and ↓ expression of tumor suppression genes) Fibroblasts proliferate and persist producing altered collagen T cells release of pro-inflammatory cytokines (interleukins and transforming growth factor β) ↑ Oxidative stress and cell damage Progressive basal layer degeneration thins the epidermis Hypopigmented patches (localized, pale areas of skin) Histamine receptor binding stimulates sensory nerve endings Localized area appears red Localized histamine release Localized vasodilation (↑ blood flow) Superficial dermal edema (swelling) Pruritus Erythema Collagen deposits and hyalinizes (transforms into acellular translucent material) beneath the epidermal layer Normal Skin Sclerotic plaques (localized areas of thickened skin) Epidermal layer Basal layer Dermal-Epidermal Junction Dermal layer Skin fissures (linear cleavage of skin) Bleeding Erosion/Ulceration Epidermal atrophy (crinkling paper- type skin appearance) Lichen Sclerosus Atrophic Epidermal layer Hyalinized collagen deposits Basal layer degeneration Band of T-cell infiltrate Dermal layer Fibrotic tissue deposition following healing of damaged tissue Scarring Lichen Sclerosus (genital manifestation): Pathogenesis and clinical findings Authors: Mina Youakim Reviewers: Elise Hansen Sunawer Aujla Shahab Marzoughi Name Name* * MD at time of publication Pruritus Histamine receptor binding stimulates sensory nerve endings Localized area appears red Erythema Unknown triggers Genetic predisposition (HLA-DQ7 and HLA-DR12) Chronic inflammation and trauma Medications (e.g. carbamazepine, pembrolizumab, nivolumab, ipilimumab) ↑ Activation and infiltration of CD4+ and CD8+ T cells into the dermal-epidermal junction T-cells proliferate in a band formation Pro-inflammatory response activation ↑ Expression of MicroRNA-155 (short segment of RNA which enhances pro-inflammatory response and ↓ expression of tumor suppression genes) Fibroblasts proliferate and persist producing altered collagen T cells release of pro-inflammatory cytokines (interleukins and transforming growth factor β) Localized histamine release Localized vasodilation (↑ blood flow) Superficial dermal edema (swelling) Collagen deposits and hyalinizes beneath the atrophic epidermal layer Hypopigmented patches (localized, pale areas of skin) ↑ Oxidative stress and cell damage Progressive basal layer degeneration thins the epidermis Skin fissures Lichen Sclerosus Epidermal atrophy (crinkling paper- type skin appearance) Sclerotic plaques (localized areas of thickened skin) Bleeding Scarring Erosion/Ulceration Normal Skin Epidermal layer Basal layer Dermal-Epidermal Junction Dermal layer Atrophic Epidermal layer Hyalinized collagen deposits Basal layer degeneration Band of T-cell infiltrate Dermal layer Legend: Published MONTH, DAY, YEAR on www.thecalgaryguide.com Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications

Post-Renal Acute Kidney Injury AKI

Post-Renal Acute Kidney Injury (AKI): Pathogenesis and clinical findings Blood clot or cellular debris Foreign body Neurogenic bladder Obstruction intrinsic to urine excretion system Nephrolithiasis (kidney stones) Anatomical defect(s) Intra- abdominal adhesions Retroperitoneal fibrosis (scar-like tissue) Benign or malignant masses Prostate cancer Benign prostatic hyperplasia ↓ Urine flow across point of obstruction Obstruction extrinsic to urine excretion system Urine buildup distends urine collecting system (hydronephrosis) Compression of renal vasculature due to mass effect ↑ Volume/pressure proximal to obstruction ↑ Intratubular pressure ↓ Pressure gradient between glomerular afferent arteriole and Bowman’s space Casts occlude tubules ↓ Filtration of plasma into nephrons ↓ Glomerular Filtration Rate (GFR) Obstruction is relieved ↓ Intratubular pressure Rapid GFR ↑ Rapid diuresis of fluid and electrolytes Dilated pelvicalyceal system on ultrasound ↓ Urine output ↓ Venous drainage and arterial supply Local ischemia and inflammation of kidney Impaired resorption, excretion, and fine tuning by tubules Acute Tubular Necrosis (ATN) with granular casts ↓ Urine output ↓ Clearance of free water and solutes ↑ Intravascular volume ↑ Serum creatinine ↓ Medullary solute concentration, ischemia, ↓ response of collecting ducts to antidiuretic hormone Lasts > 24hrs Post-obstructive diuresis causes hypovolemia and electrolyte derangements Authors: David Campbell, Matthew Hobart Reviewers: Raafi Ali, Luiza Radu Huneza Nadeem, Marissa Zhang, Julian Midgley* * MD at time of publication Resolves < 24hrs in euvolemia Physiologic post- obstructive diuresis ↑ Na+ and Cl- delivery to distal convoluted tubule is sensed by macula densa Secretion of adenosine by macula densa Adenosine constricts afferent arterioles ↓ GFR ↓ Renal clearance of drugs and waste products ↑ Venous hydrostatic pressure ↑ Volume in arterial system overwhelms pressure regulation mechanisms Hypertension Fluid extravasation from veins and capillaries Generalized Edema Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Mar 25, 2024 on www.thecalgaryguide.com

Irritant Contact Dermatitis Pathogenesis and Clinical Findings

Irritant Contact Dermatitis: Pathogenesis and clinical findings Authors: Zaini Sarwar, Mina Youakim Reviewers: Shahab Marzoughi, Ryan T. Lewinson, Yan Yu*, Laurie M. Parsons* * MD at time of publication Repeated/chronic exposure causes damage to cell membranes Skin barrier disruption Chronic non-specific inflammatory response Repetitive keratinocyte cytokine-mediated injury Keratinocytes exhibit ↑ proliferation as a compensatory response Rapid turnover of stratum corneum (outermost layer of the epidermis) Hyperkeratotic skin is less amenable to skin stretching and pressure Skin fissures (cracks in the skin) Irritant agents (abrasives, cleaning solution, oxidative & reducing agents, dust, soils, water) Acute exposure triggers inflammatory response Keratinocytes undergo cytotoxic damage with ↑ neutrophil & cytokine release Common occupational exposures (housekeeping, cleaning, catering, medical/dental, construction) Risk factors (atopy, fair skin, low temperature, low humidity) Stimulation of local nociceptors (free nerve endings extend into the mid epidermis) Perivascular (around the blood vessel) inflammation causes histamine release from mast cells Damaged keratinocytes are destroyed via apoptosis (programmed cell death) Epidermal Necrosis (death of epidermal tissue) Shedding of necrotic tissue Ulceration (deep open wound on skin) Burning pain (uncomfortable stinging sensation) Pruritus (itching) Histamine causes local blood vessel dilation and ↑ blood flow to the area of skin affected Erythema (area appears red from ↑ blood flow) Burning & Itching Spongiosis Neutrophils Neutrophils Histamine causes local blood vessel walls to have ↑ permeability, thereby ↑ leakage of fluid Spongiosis (↑ fluid between keratinocytes in the epidermis) Fluid continues to build up from ongoing inflammation Vesiculation (fluid collections in the epidermis) Long-term skin scratching causes chronic irritation which eventually hardens the skin Lichenification (thick, hardened patches of skin) ↑ Overall keratin production Hyperkeratosis (thickening of the outermost skin layer) Further fluid buildup bursts vesicles leaving behind erosions and dried crust on the epidermis Crust (scaling over the skin) Lichenification Erosions (open sore on skin) Ulcer Epidermis Perivascular Inflammation Hyperkeratosis Dermis Dermal-epidermal junction Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Oct 19, 2016; updated Mar 30, 2024 on www.thecalgaryguide.com

Deep Partial Thickness Burns Pathogenesis and Clinical Findings

Deep Partial Thickness Burns: Pathogenesis and clinical findings Radiation (Sunlight, x-ray, nuclear emission/explosion) Ionizing radiation gets into contact with DNA Damage to keratinocytes Fire (Flash fire or direct contact with flame) Contact (Hot solid objects) Scalding (Hot liquid via immersion, spill or splash) Chemical (Strong acid, alkali or irritant gas) Electrical (Contact with exposed electrical wiring/appliances) Author and Illustrator: Amanda Eslinger Maharshi Gandhi Reviewers: Alexander Arnold Shahab Marzoughi Duncan Nickerson* * MD at time of publication Direct transfer of heat energy Coagulation necrosis (cell death due to ischemia) is induced Deep Partial Thickness Burn Injury to the epidermal layer and both the papillary and a portion of the reticular layer of the dermis Transfer of heat energy & direct injury to cellular membranes Epidermis Papillary dermis Reticular dermis Sub- cutaneous Tissue ↑ vascular permeability due to damage Fluid leak results in edema between dermal & epidermal layer Blisters (a bubble on the skin containing fluid) Thin epidermal layer forming fluid-filled vesicle breaks open Cutaneous capillary bed is destroyed Blood flow to injured area is compromised Pressing on the skin doesn’t easily force blood cells out of the area Non-blanchable skin Vasodilation in fascia (a thin casing of connective tissue) underlying subcutaneous tissue Inflammatory mediators such as cytokines and prostaglandins activate fibroblasts Collagen deposition and subsequently induration (thickening of skin) Some healthy dermal appendages surrounded by islands of undamaged epithelial cells Possible spontaneous re-epithelialization in 2-9 weeks During re-epithelization of burns there can be excessive deposition of collagen and other extracellular matrix components Thick raised scars in dermis due to excess collagen deposition Somatosensory structures (nociceptors, thermoreceptors, and mechanoreceptors) are completely injured within the dermis Analgesia of impacted area (the inability to feel pain) Ongoing Inflammation and dilated blood vessels Red Induration (Thickened skin appearing red) Compromised blood flow and more extensive tissue damage White Induration (Thickened skin appearing white) Moist Wound Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Dec 2, 2013, updated Apr 20, 2024 on www.thecalgaryguide.com

Costochondritis

Costochondritis: Pathogenesis and clinical findings Systemic infection originating in upper respiratory tract (commonly Staphylococcus aureus and Streptococcus bacterial infections) Infection spreads through blood to ribcage and chest wall Age-related degeneration of cartilage within ribcage joints Immune cells present in joints secrete proinflammatory cytokines Cytokines sensitize nociceptors (pain receptors) in joints Repetitive trauma or strain to chest wall muscles (e.g. chronic cough, chest wall injury, overexertion of chest wall muscles) Excessive stretch and tearing of ribcage cartilage and ligaments Autoimmune disease (e.g. rheumatoid arthritis) Antigen presenting cells display self-antigens to CD4+ T cells Mechanical stimuli (e.g. Damaged cells release cytokines Pathogens activate immune cells at site of stretch) activate nociceptors that recruit immune cells inflammation Costochondritis Benign inflammation of the ribcage (costal) cartilage, particularly at the costosternal junctions (connection between sternum and cartilage) and the costochondral junctions (connection between the cartilage and rib) Authors: Michelle J. Chen Reviewers: Raafi Ali Yan Yu* Gerhard Kiefer* * MD at time of publication Cartilage, ligament, or muscle injury Presence of foreign pathogen in costal cartilage Injury or pathogen activates inflammatory cascade in the ribcage cartilage Immune cells proliferate so that they exceed the available space in the cartilage matrix of the ribcage Cartilage swelling compresses intercostal nerves Compression acts as a mechanical stimulus to activate nociceptors Sharp, localized pain reproducible upon palpation over ribcage Immune cells secrete cytokines Cytokines activate nociceptors so that they become more sensitive to mechanical stimuli Muscle or ligament stretch from normal use activates sensitized nociceptors Pain increases with inspiration or cough Natural resolution of inflammation over time Macrophages phagocytose apoptotic cells (immune and cartilage cells) and cellular debris Immune cells release factors that degrade proinflammatory cytokines Fewer cytokines reduce immune cell recruitment into costal cartilage Pain usually self-resolves Immune cells release lipid molecules that bind to the same cells (autocrine signaling) to inhibit further production of inflammatory cytokines and chemokines Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Apr 29, 2024 on www.thecalgaryguide.com

Acute Otitis Media Complications

Acute Otitis Media: Complications Prolonged mucus buildup or swelling in Eustachian tube due to colds/allergies obstructs the Eustachian tube Fluid unable to drain through tube and accumulates in middle ear Acute Otitis Media Infection and inflammation of the middle ear Mastoid air cells are in physical contact with distal middle ear Pathogens move into mastoid air spaces Inflammation & infection in air spaces Mastoiditis Bacterial and immune cell debris (pus) accumulates in mastoid air spaces Untreated middle ear infection allows further bacterial proliferation Persistent effusion causes ion channel changes in inner ear Composition of endolymph and perilymph in inner ear changes Vestibular/Labyrinth dysfunction Feelings of Vertigo imbalance Purulent discharge from middle ear through perforation Otorrhea (ear discharge) ↑ Pressure in middle ear Pressure stretches tympanic membrane Cytokines reach hypothalamus through the bloodstream Hypothalamus responds to stimulation and ↑ thermoregulatory set-point High-grade fever Infection spreads into bloodstream Sepsis Cytokines alter metabolism pathways of neurotransmitters in the brain Cerebral cortex dysfunction Infection spreads to cranium Intracranial complications (e.g., meningitis, brain abscess, thrombus) Author: Jody Platt Stephanie de Waal Reviewers: Yan Yu Elizabeth De Klerk William Kim Annie Pham Michelle J. Chen Danielle Nelson* * MD at time of publication Helper T cells and macrophages release inflammatory cytokines into the bloodstream Perforation of tympanic membrane ↓ Conduction of sound waves Conductive hearing loss Pressure in middle ear diffuses out of perforation ↓ Tympanic membrane stretching Otalgia (ear pain) fades Accumulated debris compresses cranial nerve VII Facial nerve palsy Mastoid abscess Febrile seizures Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Feb 28, 2013, updated Apr 29, 2024 on www.thecalgaryguide.com

Sickle Cell Disease Pathogenesis Clinical Findings and Complications

Sickle Cell Disease: Pathogenesis, Clinical Findings, and Complications DNA point mutation in chromosome 11 causes a substitution of glutamate to valine for the sixth amino acid of the β-globin chain Authors: Yang (Steven) Liu Priyanka Grewal Reviewers: Alexander Arnold Luiza Radu JoyAnne Krupa Yan Yu* Lynn Savoie* * MD at time of publication Hemoglobin S (HbS) variant formed instead of normal Hemoglobin A (HbA) Hb electrophoresis shows approximately 45% HbS, 52% HbA (ααββ), 2% HbA Hb electrophoresis shows approximately 90% HbS, 8% HbF, & 2% HbA . No HbA present (ααδδ), & 1% HbF (ααγγ;2 fetal hemoglobin) Heterozygous: point mutation in one of the two chromosomes (Hb AS) Sickle cell trait (asymptomatic unless severely hypoxic) Homozygous: point mutation in both chromosomes (Hb SS) Sickle cell disease An inherited blood disorder characterized by defective hemoglobin that leads to red blood cells sickling 2 Dehydration Hypoxemia Acidosis ↓ Volume of RBC cytoplasm ↓ O2 Saturation of Hb O morereadily 2 released from Hb in low pH environment ↑ Concentration of deoxygenated HbSinred blood cells (RBCs) Hydrophilic glutamate→ hydrophobic valine substitution makes HbS less soluble in the cytoplasm & more prone to polymerization & precipitation in its deoxygenated state ↑ Concentration of deoxygenated Hb in RBC leads to ↑ polymerization rate Polymerized & precipitated HbS forms long needle-like fibers RBC shape becomes sickled Sickle cells on peripheral blood smear Vaso-occlusion (sickled RBCs lodge in small vessels, blocking bloodflow to organs & tissues) Blockage of venous outflow Occlusion of vessels in lungs ↑ pulmonary blood pressure Fluid extravasates into interstitial tissue leading to pulmonary edema Acute chest syndrome (chest pain, hypoxemia (↓blood oxygen), etc.)** to the penis: to the spleen: Priapism (persistent, painful erection) Splenic Sequestration (blood pools in spleenà splenomegaly & hypotension) Extravascular hemolysis (macrophages in the spleen phagocytose sickled RBCs) Normocytic anemia ↑Marrow erythropoiesis (RBC production) to compensate for hemolysis Infarction of bone Pain crises If occurring in hands Dactylitis (inflammation of digits) Blockage of arteries ↓ oxygenation of organs & tissues Vaso-occlusion of the splenic artery Splenic infarction (↓ blood supply leads to tissue death) RBC inclusions (structures found in RBCs) not removed by spleen Howell-Jolly bodies (RBC DNA remnants) on blood smear Vaso-occlusion of other arteries (cranial, renal, etc) Stroke, renal failure ↑ RBC breakdown ↑ Unconjugated bilirubin released from RBC breakdown RBC precursors (reticulocytes) are released into the blood stream Reticulocytosis (increased number of immature red blood cells) on peripheral blood smear Patient’s RBC level becomes dependent on increased marrow activity Bone marrow infarction or viral infections (i.e. Parvovirus B19) suppresses bone marrow activity Aplastic crises (profound anemia) ** See corresponding Calgary Guide slide(s) ↑ Serum level of unconjugated bilirubin Some of the circulating unconjugated bilirubin deposits in the skin Jaundice (yellowing of skin) ↑ Conjugation of bilirubin in liver ↑Amounts of conjugated bilirubin released into bile Gallstone formation Cholelithiasis (presence of gallstones in the gallbladder) Spleen releases invasive encapsulated bacteria (eg. Haemophilus influenzae, Streptococcus pneumoniae, Neisseria meningitidis) into circulation, which causes infections Meningitis Sepsis Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Sept 16, 2013, updated Apr 29, 2024 on www.thecalgaryguide.com

Wiskott-Aldrich Syndrome

Wiskott-Aldrich Syndrome (WAS): Pathogenesis and clinical findings X-linked recessive inheritance (mostly males impacted) Spontaneous DNA mutation Genetic mutations in Wiskott-Aldrich Syndrome Protein (WASP) impair actin cytoskeleton remodeling in hematopoietic cells (immature blood cells) Authors: Mina Mina Reviewers: Hana Osman Mao Ding Maharshi Gandhi Shahab Marzoughi Louis-Philippe Girard* * MD at time of publication Megakaryocytes (platelet precursor cells) depend on the cytoskeleton changing shape to form pseudopodia (arm-like projections) which bud off forming cellular fragments (platelets) Abnormal cytoskeleton reorganization leads to ineffective thrombocytopoiesis (production of platelets) Microthrombocytopenia (↓ platelet size and quantity) Issues with formation of a platelet plug due to abnormal platelets (dysfunction of primary hemostasis) Reduced ability for platelet adhesion, activation, and/or aggregation Natural killer cells depend on the cytoskeleton reorganization to form immunological synapses (communication) with body cells in order to have effective surveillance T cells depend on the cytoskeleton remodeling to form pseudopods which allow them to synapse with other cells when a pathogen is encountered Defective immune synapse formation ↓ Cancer immunosurveillance ↑ Risk of malignancy Helper T cells cannot activate B cells which generate antibodies (immunoglobulins) to destroy pathogens Regulatory T cells can not sufficiently downregulate effector cells which typically limit the immune response and prevent autoimmune conditions ↑ Risk of autoimmune diseases Recurrent opportunistic infections Immune dysregulation Impaired immune response ↓ Number and function of T cells Immune responses contribute to Type 2 immune responses Atopic dermatitis (AD; chronic inflammation that causes itchy skin) ↑ Immunoglobulin (Ig) A Epistaxis (nosebleed) Red blood cells leak from capillaries Menorrhagia (heavy menstrual bleeding) Petechiae (small, flat, red spots that appear on the skin) Inflammation in AD triggers release of interleukins (modulatory proteins during inflammatory and immune responses) leading to Immunoglobulin (Ig) class switching ↑ IgE levels Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Apr 20, 2024 on www.thecalgaryguide.com

Scabies pathogenesis and clinical findings

Scabies: Pathogenesis and clinical findings Direct person-person transmission of Sarcoptes Scabiei var. hominis to new host Fertilized females secrete proteolytic enzymes that allow them to burrow through the stratum corneum (2 mm/day) Authors: Heena Singh Amanda Eslinger Nirav Saini Reviewers: Shahab Marzoughi Danny Guo Yan Yu Richard Haber* * MD at time of publication Mechanical irritation and immunological reaction Mast cell activation and histamine release Itch (> 10 Mites) Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale Females lay 2-3 ova/day which hatch in the stratum corneum in pockets after 3 days The larvae molt and mature for 2 weeks and mate within the pockets of the stratum corneum Following mating, female mites begin burrowing Cycle is propagated as new female mites create more burrows in stratum corneum Superficial, Linear, Tortuous (i.e., Twisted) +/- Scaly Burrows ↑ Exposure to mite antigens such as Sar s 14.3 and Sar s 14.2 Type 2 helper T-cells produce proteins IL-4, IL-5, IL-13 ↑ Serum Immunoglobulin G & E ↑ Eosinophil Count in Peripheral Blood Inappropriate T helper-type immune response in skin (mechanism unknown) Antigens forming from mite feces, ova, or decomposing bodies Type IV hypersensitivity reaction (delayed immune response 2-4 weeks following initial contact) Skin barrier dysfunction from inflammation and histamine release Pre-existing immunosuppression Chronic inflammatory response Allergic reaction to ↑ mite activity at night Uncontrollable Itch (Worse At Night) + Excoriations (Scratch Marks) Urticarial (Hive-Like) Crusted Papules Eczematous Plaques Skin breakdown Opening for bacteria (commonly S. aureus) 2° Bacterial infection Pustules Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Oct 17, 2013; updated Jun 9, 2024 on www.thecalgaryguide.com

Posterior Cruciate Ligament PCL Injury Pathogenesis and Clinical Findings

Posterior Cruciate Ligament (PCL) Injury: Pathogenesis and clinical findings Authors: Luc Wittig Stephanie de Waal Michelle J. Chen Reviewers: Reza Ojaghi Usama Malik Sunawer Aujla Nojan Mannani Mankirat Bhogal Dr. R. Buckley* Dr. Gerhard Kiefer* * MD at time of publication Sport-related trauma Dashboard knee injury from a motor vehicle collision Tibia contacts dashboard at high velocity with knee in flexed position Tibia is forced posteriorly, relative to knee joint The PCL undergoes sudden & forceful strain Hyperextension injury (knee joint moves past its normal extension limit) Extreme tibia movement anteriorly past knee joint overstretches PCL Hard fall on flexed knee Posterior Cruciate Ligament Injury Strain & overstretching of the PCL, which connects the anterior distal femur to the posterior proximal tibia to prevent posterior translocation of the tibia relative to the femur, can result in a partial or complete tear. The tear can be isolated (rare) or be one of multiple ligaments that are torn (multi-ligamentous tear). Mild injurious force causes a partial tear Intact portion of PCL prevents extreme tibial translocation posterior to the femur. Torn portion still allows 1-5 mm of posterior tibial translocation (Grade 1) Positive posterior drawer test Knee injury tests • Posterior drawer test – Push against leg below the knee to test for posterior tibial translocation relative to femur • Lachman test – Pull leg below the knee to test for anterior tibial translocation relative to femur • McMurray test – Tests for medial and lateral meniscus tears • Varus & valgus stress test – Tests for medial and Strong injurious force causes a complete, isolated tear PCL is unable to prevent posterior translocation of the tibia relative to the femur, allowing 6-10 mm of posterior tibial translocation (Grade 2) Positive posterior Negative Lachman, McMurray, drawer test and varus & valgus stress test Very strong injurious force causes a multi- ligamentous tear and damage to the knee joint capsule (capsuloligamentous injury) Absence of stability from PCL combined with absence of stability from other knee ligaments allows for > 10 mm of posterior tibial translocation (Grade 3) Positive posterior Positive Lachman OR McMurray drawer test OR varus & valgus stress test PCL unable to stabilize knee by preventing posterior tibial translocation (chronic PCL insufficiency) Body uses quadriceps tendon for knee stabilization to compensate for PCL insufficiency Inflammation from injury contributes to progressive degenerative articular changes lateral collateral ligament tears Post-traumatic patellofemoral pain Osteoarthritis Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Sept 20, 2018; updated Jun 9, 2024 on www.thecalgaryguide.com

Migraines and auras pathogenesis and clinical findings

Migraines and Auras: Pathogenesis and clinical findings Genetic mutations at certain loci (e.g., Familial hemiplegic migraine mutation in gene encoding P/Q-type Ca2+ channels) Personal triggers (e.g., lack of food, emotional stress) “Cortical Spreading Depolarization” followed by “Cortical Spreading Depression” across one cortical hemisphere Cortical spreading depression creates “auras” via unknown mechanism(s) Expanding scotoma (area of visual blurriness) Spreading paraesthesias (numbness that travels across body) Dysphasic language (trouble finding words) Brainstem symptoms (e.g., vertigo, tinnitus) Motor symptoms (e.g., hemiplegia) Triggering of a depolarization wave in a unilateral region of the cortex with associated ↑ blood flow to that region Neurons and glia release K+ into extracellular space that spreads depolarization wave to nearby cortical areas Ion gradient imbalances cause Prolonged vasoconstriction neurons in original cortical area to and ↓ blood flow swell and become inhibited Activation of the hypothalamus (responsible for maintaining homeostasis) Prodromal symptoms (↑ thirst, hunger, yawning, ↓ cognitive function) Author: Yan Yu Braxton Phillips Reviewers: Shahab Marzoughi Owen Stechishin Dustin Anderson Scott Jarvis* Sina Marzoughi* * MD at time of publication Release of hypothalamic neurotransmitters (e.g., orexins, neuropeptide Y) at the trigeminalcervical complex (TCC) of the brainstem and cervical spinal cord Depolarizing wave passes over pseudounipolar neurons (neurons with two axons) of the trigeminal ganglion which synapse in brainstem & dura matter These neurotransmitters reduce the activation threshold of spinal trigeminal nucleus neurons in the TCC Neuropeptides (e.g., calcitonin gene-related peptide, pituitary adenylate cyclase-activating polypeptide) are released at the TTC, triggering local inflammation (termed neurogenic inflammation) Ongoing neurogenic inflammation activates secondary nociceptive neurons in the TTC Central sensitization (↓ response threshold of secondary nociceptive neurons in the TTC) Brain perceives referred pain from the face as the TTC also receives convergent nociceptive input from the face Facial allodynia (pain with normally non-painful stimuli) Serotonin & histamine are released on dural blood vessels triggering neurogenic inflammation in the dura matter Ongoing neurogenic inflammation activates primary nociceptive neurons in the dura matter Peripheral sensitization (↓ response threshold of primary nociceptive neurons around the dural blood vessels_ Unknown mechanisms no longer believed to be related to dural blood vessel dilation Unilateral throbbing headache Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Nov 22, 2012, updated Jul 1, 2024 on www.thecalgaryguide.com

Legg Calve Perthes Disease

Legg-Calvé-Perthes Disease: Signs and Symptoms Idiopathic abnormalities in the common pathway of the blood clotting cascade ↑ blood thickness Initial stage (6 months) Early interruption of blood supply to femoral head ↓ Venous outflow from intraosseous vasculature ↑ pressure within bone Fragmentation stage (8 months) Body replaces resorbed necrotic bone with structurally weaker bone Backup of blood within bone vasculature impedes arterial inflow Temporary interruption of blood supply to proximal femoral epiphysis primarily during childhood Residual stage Differential growth of proximal femoral epiphysis Overgrowth of greater trochanter Healing stage (4 years) Body gradually replaces necrotic bone with stronger, more dense bone Lack of O2 & nutrients disrupts normal bone growth Bone tissue begins dying from loss of O2 & nutrients (osteonecrosis) Osteonecrosis is associated with inflammation of synovial tissue (synovitis) at the femoral head Metaphyseal cyst (area of bone resorption) grows on proximal femoral neck metaphysis Growth plate abnormalities Femoral bone head deformity Limited hip internal rotation & abduction Antalgic gait Femoral epiphysis collapses laterally and extrudes from acetabulum Femoral head now composed of dense and less dense bone Scattered radiolucency & radiodensity on plain radiographs Femoral head deformity becomes set in place and limits hip range of motion Femoral bone head deformity Limb length discrepancy Normal bone density on plain radiographs Abnormal articulo- trochanteric distance (vertical distance between highest point of greater trochanter & highest point of femoral head) Remodeling of femoral head & acetabulum seen on plain radiographs Growth plate irregularity ↓ Range of motion Widened medial joint space Antalgic gait Femoral head is displaced laterally Fragmented epiphysis on plain radiographs Groin pain & referred pain to anteromedial thigh or knee region Authors: Janelle Wai Michelle J. Chen Reviewers: Patrick Pankow Nojan Mannani Kirat Bhogal Dr. Gerhard Kiefer* * MD at time of publication Findings on magnetic resonance imaging (MRI) & plain radiographs Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published July 19, 2024 on www.thecalgaryguide.com

Acute Otitis Media Pathogenesis and Clinical Findings in Children

Acute Otitis Media in Children: Pathogenesis and clinical findings Congenital conditions (e.g. Down Syndrome, Pierre Robin syndrome) Exposure to tobacco smoke Impaired macrophage function in nasopharynx Lack of immunizations Lack of breastfeeding Infant does not receive antibodies from breast milk Overcrowding Age 6 – 16 months Immune system deficiencies Close proximity of kids & ↓ sanitation (e.g. daycare) ↑ Infection risk Upper Respiratory Tract Infection (i.e. bacterial (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis), viral) Immature Eustachian tube anatomy which facilitates pathogen transmission to middle ear Author: Jody Platt Stephanie de Waal Reviewers: Yan Yu Elizabeth De Klerk William Kim Annie Pham Michelle J. Chen Danielle Nelson* * MD at time of publication Abnormal anatomical structure (e.g. cleft palate) ↑ Nasopharyngeal streptococcus pneumoniae Lack of immunity to pathogens ↑ Colonization of nasopharynx with bacterial pathogens Inflammation & edema of respiratory mucosa including the nose, nasopharynx, and Eustachian tube Obstruction of the Eustachian tube Air from middle ear resorbs into circulation which creates a low-pressure environment Negative pressure gradient pulls viral/bacterial pathogens into middle ear Degenerating white blood cells, tissue debris, and microorganisms accumulate & develops into purulent effusion Inflammation & infection of middle ear Complications of acute otitis media** ↑ Pressure in middle ear Stretching of tympanic membrane Helper T cells & macrophages release cytokines into the bloodstream Cytokines trigger hypothalamus to ↑ thermoregulatory set-point Effusion behind tympanic membrane Effusion obstructs visualization of ossicles Neutrophils infiltrate middle ear & phagocytose pathogens Pus accumulates behind the tympanic membrane Blood vessels of the tympanic membrane vasodilate Bulging tympanic membrane Otalgia (ear pain) Discomfort disrupts daily activities in young children Fever Irritable Poor feeding Tympanic membrane erythema Painful blisters on tympanic membrane (e.g. Bullous myringitis) Can persist for up to 3 months after infection resolves Loss of tympanic membrane landmarks (i.e. handle of malleus, light reflex) ** See corresponding Calgary Guide slide Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Feb 28, 2013; updated Aug 25, 2024 on www.thecalgaryguide.com

Pediatric Pneumonia Pathogenesis and Clinical Findings

Pediatric Pneumonia: Pathogenesis and clinical findings Authors: Jasmine Nguyen Nicola Adderley Reviewers: Midas (Kening) Kang Usama Malik Annie Pham Eric Leung* Jean Mah* * MD at time of publication Immunological: unvaccinated, primary immunocompromise, pre-existing illness (e.g. HIV, measles), malnutrition Environmental: smoke, air pollution, mold, crowded housing Recent hospitalization or antibiotic-use Physiological: neonates, low-birth weight, underlying lung disease These factors make the host more susceptible to infection Infection and proliferation of pathogen in lower respiratory tract/parenchyma Pediatric pneumonia: Inflammatory response to infection/proliferation of microbial pathogens at the alveolar level Exposure to pathogen via inhalation, hematogenous, direct exposure, or aspiration Epithelial cells in respiratory tract release cytokines that recruit neutrophils & plasma proteins to infection site, initiating a local inflammatory response Cytokines released into the bloodstream (e.g. TNF, IL-1) initiate a systemic inflammatory response ↑ Vascular permeability Accumulation of exudate, cellular debris, serous fluid, fibrin, or bacteria in the airway spaces ↑ Respiratory drive Tachypnea ↑ Excitability of the peripheral somatosensory system Circulating cytokines induce prostaglandin synthesis Airway irritation as cilia are unable to efficiently clear fluid buildup Crackles, ↓ breath sounds Fluid, protein, or inflammatory cells leak into pleural space Pleural effusion Pulmonary edema Fluid buildup in interstitial spaces ↑ gas diffusion distance Bacteria enter the bloodstream (if bacterial pneumonia) Sepsis Fluid buildup in the alveoli ↓ available surface area for gas diffusion ↓ Efficiency of gas exchange Intra- and extracranial arteries dilate Headache ↑ Thermo-regulatory set-point of the hypothalamus Fever Myalgia Hypoxemia Malaise Cough Fluid accumulation in the pleural space prevents full lung expansion ↑ Work of breathing (tracheal tug, paradoxical abdominal breathing, subcostal/suprasternal indrawing) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published May 28, 2018; updated Aug 25, 2024 on www.thecalgaryguide.com Pediatric Pneumonia: Pathogenesis and clinical findings Authors: Jasmine Nguyen Nicola Adderley Reviewers: Midas (Kening) Kang Usama Malik Annie Pham Eric Leung* * MD at time of publication Immunological: unvaccinated, primary immunocompromise, pre-existing illness (e.g. HIV, measles), malnutrition Environmental: smoke, air pollution, mold, crowded housing Recent Hospitalization: length of stay, recent antibiotics, mechanical ventilation Physiological: neonates, low-birth weight, underlying lung disease (ciliary dysfunction, asthma, cystic fibrosis, bronchiectasis) Host is more susceptible to infection Exposure to pathogen: inhalation, hematogenous, direct, aspiration Infection and proliferation of pathogen in lower respiratory tract/parenchyma Pediatric pneumonia: Inflammatory response to infection/proliferation of microbial pathogens at the alveolar level Notes: • Additional findings in pediatric pneumonia may include increased irritability, nausea/vomiting, diarrhea, otitis, and headache • Viral pathogens most common in children <2yrs; bacterial pathogens most common in children >2yrs Local inflammatory response: epithelial cells release cytokines in response to infection, which recruit neutrophils and plasma proteins to site of infection ↑ Vascular permeability causes accumulation of plasma exudate, cellular debris, serous fluid, fibrin, or bacteria in the airway spaces Systemic inflammatory response: Cytokine release (eg. TNF, IL-1) ↑ respiratory drive Airway irritation as cilia are unable to efficiently clear fluid buildup Crackles, ↓ breath sounds Fluid, protein, or inflammatory cells leak into pleural space Pleural effusion Pulmonary edema Fluid buildup in interstitial spaces increases gas diffusion distance Fluid buildup in the alveoli decreases available surface area for gas diffusion ↓ efficiency of gas exchange Bacteria invade into the bloodstream (if bacterial pneumonia) Sepsis Hypoxemia Circulating cytokines induce prostaglandin synthesis, which raise the thermoregulatory set-point of the hypothalamus paradoxical abdominal breathing, subcostal/suprasternal indrawing) Fever Cough Fluid accumulation in the pleural space prevents full lung expansion, resulting in ↓ lung volumes Tachypnea ↑ Work of breathing (tracheal tug, Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Month Day, Year on www.thecalgaryguide.com Pediatric Pneumonia: Pathogenesis and clinical findings Immunological: immunization status, immune compromise Environmental: second-hand smoke, air pollution Hospitalization: length of stay, recent antibiotics, mechanical ventilation Neonates, immunocompromise, underlying lung disease (ciliary dysfunction, Cystic Fibrosis, bronchiectasis) Authors: Nicola Adderley Reviewers: Midas (Kening) Kang Usama Malik Eric Leung* * MD at time of publication Additional findings in pediatric pneumonia may include nausea, otitis, headache Viral pathogens most common in children <2yrs; bacterial pathogens most common in children >2yrs Interstitial pattern: suspect Mycoplasma pneumoniae, Influenza A + B, Parainfluenza Lobar pattern: suspect S. pneumonia, H. influenzae, Moraxella, S. aureus Systemic inflammatory response: Cytokine release (eg. TNF, IL-1) Exposure to pathogen: inhalation, hematogenous, direct, aspiration Susceptible host and/or virulent pathogen Infection and proliferation of pathogen in lower respiratory tract/parenchyma Pediatric pneumonia: Inflammatory response to proliferation of microbial pathogens at the alveolar level Notes: • • • • Local inflammatory response: neutrophils recruited to site of infection (LOBAR or INTERSTITIAL PATTERN, depending on pathogen) by epithelial cytokine release Irritation of contiguous structures and/or referred pain (mechanism unclear) Acute abdominal pain Cough Accumulation of plasma exudate (from capillary leakage at sites of inflammation), cell-debris, serous fluid, bacteria, fibrin ↑ respiratory drive Disruption of hypothalamic thermoregulation Fever/chills Irritation of airways and failure of ciliary clearance to keep up with fluid buildup Crackles, ↓ breath sounds Fluid buildup in spaces between alveoli (INTERSTITIAL PATTERN) Interstitial opacity on CXR Fluid buildup in alveoli (LOBAR PATTERN) ↓ efficiency of gas exchange (↑ diffusion distance in INTERSTITIAL, ↓ surface area in LOBAR) Hypoxemia Tachypnea Lobar consolidation on CXR Respiratory accessory muscle use (chest indrawing, paradoxical breathing, muscle retractions) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published May 28, 2018 on www.thecalgaryguide.com gin