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