Aspiration pneumonia and pneumonitis

Background

  • Difficult to predict which patients with pneumonitis will go on to develop pneumonia
  • Aspiration pneumonitis
    • Inflammatory chemical injury of tracheobronchial tree and pulmonary parenchyma
    • Due to inhalation of regurgitated sterile gastric contents
    • Must aspirate at least 20-30mL of gastric contents with pH <2.5
    • Can lead to aspiration pneumonia due to pulmonary defense mechanism injury
  • Aspiration pneumonia
    • Alveolar space infection secondary to inhalation of pathogenic material from oropharynx
    • Increased in patients with periodontal disease, chronic colonization of upper airways, or taking PPI/H2-blockers
    • Accounts for up to 20% of community-acquired pneumonia in elderly, majority of nursing home-acquired pneumonia
    • Microbiology
      • Community acquired: Pneumococcus, staph, H flu, enterobacter
      • Hospital acquired: Pseudomonas, gram-negatives

Clinical Features

  • Aspiration pneumonia
    • Fever
    • Dyspnea
    • Productive cough
    • Tachypnea
    • Tachycardia
    • Altered mental status
  • Aspiration pneumonitis
    • Cough
    • Tachypnea
    • Bloody sputum
    • Respiratory distress

Differential Diagnosis

Acute dyspnea

Emergent

Non-Emergent

Evaluation

Work-Up

  • CXR
    • Unilateral focal or patchy consolidations in dependent lung segments
    • Right lower lobe is most common area; bilateral patterns can also be seen
    • Lower lobe infiltrate when aspiration occurs in upright position
    • Upper lobe infiltrate when aspiration occurs in recumbent position
  • CT
    • Increased sensitivity, specificity, and overall accuracy compared to CXR
    • Reasonable to obtain even if CXR negative if clinical suspicion is high

Management

Disposition

  • Admit all patients with aspiration pneumonia
  • For aspiration pneumonitis, consider discharge if:
    • Otherwise healthy and non-toxic
    • Give outpatient antibiotics if symptomatic for >48hrs
  • For aspiration pneumonitis, consider admission for:
    • Chronically ill or immunocompromised
    • Nursing home patient

See Also

References

Authors:

Michael Holtz