Aspiration pneumonia - Pulmonary
Aspiration pneumonia can lead to sepsis or acute respiratory distress syndrome (ARDS) and can result in hypoxia and hemodynamic instability. An initial evaluation of the patient's condition and vital signs will determine the need for supplemental oxygen, or even intubation, and possibly vasopressors. Intravenous (IV) access, fluids, and antibiotics may need to be initiated promptly.
Aspiration pneumonia is a bacterial infection of the lung parenchyma resulting from the entry of oropharyngeal or gastric contents, with compromise in the usual upper or lower airway defenses of uncleared matter.
The infection is often polymicrobial, including oropharyngeal anaerobic bacteria and aerobic bacteria. Gram-negative bacilli, Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumoniae, Haemophilus influenzae, and Enterobacteriaceae are not uncommon, particularly in individuals exposed to a health care setting.
Aspiration of small amounts of secretions occurs in healthy individuals, who are able to clear them without development of pneumonia. Patients who develop aspiration pneumonia commonly have periodontal disease and have predisposing conditions that may impair their level of consciousness, normal swallowing functions, and airway clearance mechanisms. Examples of such conditions may include impaired level of consciousness from medications, seizures, head trauma, alcohol, and drugs. Other predisposing conditions include dysphagia as it relates to neurologic or esophageal disorders, mechanical obstruction of glottic closure, cardiac arrest, cerebrovascular accidents, and parenteral feeding.
Typical bacterial aspiration pneumonia evolves with an indolent course over several days to weeks with common signs and symptoms of pneumonia. Hospital-acquired aspiration pneumonia may develop more rapidly based on bacterial organisms. Vital signs may include fever, tachycardia, hypoxia, and possibly hypotension. Complications include necrotizing pneumonia, lung abscesses, ARDS, and empyema.
Aspiration pneumonia should be distinguished from chemical pneumonitis, which is an inflammatory process that results from aspiration of gastric acid. This does not result in an infectious pneumonia but instead causes chemical injury to the lungs and usually presents with more abrupt onset of symptoms. Treatment is supportive care.
J69.8 – Pneumonitis due to inhalation of other solids and liquids
422588002 – Aspiration pneumonia
Differential Diagnosis & Pitfalls
- Community-acquired pneumonia (CAP) or hospital-acquired pneumonia (HAP) due to bacterial pathogens (eg, S pneumoniae, S aureus pneumonia)
- Pneumonia due to endemic fungi (eg, histoplasmosis, coccidioidomycosis, blastomycosis, paracoccidioidomycosis, cryptococcosis)
- Pneumonia due to other pathogens including Legionella or Nocardia
- Chemical pneumonitis – pulmonary injury secondary to gastric acid aspiration
- Pulmonary edema – cardiogenic versus noncardiogenic causes
- Tuberculosis can present with cavitary lung lesions
- Malignancy (primary lung cancer or metastases)
- Lung infarct (eg, following pulmonary embolism)
- Granulomatosis with polyangiitis
- Invasive fungal infection (aspergillosis, mucormycosis in immunosuppressed hosts)