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Asthma clinical findings

Asthma: Clinical Findings Asthma Episodic airway constriction and airflow obstruction, due to hyper- responsiveness to certain triggers (see slide on asthma pathogenesis) Author: Yan Yu Reviewers: Jason Baserman Jennifer Au Yonoglin Mai (麦泳琳) Naushad Hirani* * MD at time of publication Variable, sporadic airway obstruction in response to triggers Associated allergic eosinophil response Eosinophils infiltrate: Skin If severe: ↓ ventilation of alveoli ↓ oxygenation of blood (hypoxemia) During expiration, positive pleural pressure squeezes on airwaysà↑↑ airway obstruction Heart rate ­ to improve perfusion of tissue Tachycardia Respiratory centers ­ rate of breathing to compensate Tachypnea Gas is trapped within alveolià hyperinflates lungs Ventilating larger lungs needs more effort Patients need to voluntarily contract their expiratory muscles faster and more forcefully to effectively expire Narrower airways àturbulent airflow, heard on auscultation Expiratory Wheeze (high-pitched expiratory sound) Nose Rhinitis/ sinusitis Runny nose, sneezing, etc Atopic dermatitis Skin rash, hives Eyes Conjunctivitis Red itchy eyes, visual blurring Episodic dyspnea (shortness of breath) Chest tightness During severe attacks: Note: Asthma attacks often have two phases: • An immediate attack (within 0-2 hours of the trigger, due to acute release of histamine from mast cells) • A delayed attack (due to eosinophil infiltration of airways, presents within 3-4 hours after exposure to the trigger, peaks within 6-8 hours, and resolves within 24 hours). Keep the possibility of a delayed attack in mind when treating patients in Emergency! Note: Symptoms often worse at night or early in the morning. Note: Asthma should be suspected in children experiencing dyspnea with multiple episodes of Upper Respiratory Tract Infections or Croup. Patient compensates by activating accessory respiratory muscles to ↑ thoracic volume Visible contraction of neck muscles (Scalene, sternocleidomastoids) ↑↑↑ airway obstruction on expiration, lungs take more time to empty Prolonged expiratory phase of breathing Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Dec 17, 2012 and updated Dec 4, 2021 on www.thecalgaryguide.com

哮喘-临床表现

哮喘-临床表现