Aspiration pneumonia and pneumonitis
Background
- Difficult to predict which patients with pneumonitis will go on to develop pneumonia, aspiration alone does not cause pneumonia
- Witnessed aspiration key to distinguishing between the two
- 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
- Result of a complex interplay of the aspirated material, aspirated volume, pH, patient physiology and pulmonary defense mechanisms
- 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
Risk factors
- Advanced age
- Altered level of consciousness
- Anatomic abnormality of upper airway
- Dementia
- Esophageal disorders
- Gastroesophageal reflux
- Neuromuscular disease
- Poor oral hygiene
- Prior history of aspiration
- Prolonged supine position
- Retained gastric material
- Tube feedings
Clinical Features
- Aspiration pneumonia
- Fever
- Dyspnea
- Productive cough
- Tachypnea
- [[Tachycardia
- Altered mental status
- Aspiration pneumonitis
- Cough
- Bronchospasm
- Tachypnea
- Bloody sputum
- Low-grade fever
- Respiratory distress
Differential Diagnosis
Acute dyspnea
Emergent
- Pulmonary
- Airway obstruction
- Anaphylaxis
- Angioedema
- Aspiration
- Asthma
- Cor pulmonale
- Inhalation exposure
- Noncardiogenic pulmonary edema
- Pneumonia
- Pneumocystis Pneumonia (PCP)
- Pulmonary embolism
- Pulmonary hypertension
- Tension pneumothorax
- Idiopathic pulmonary fibrosis acute exacerbation
- Cystic fibrosis exacerbation
- Cardiac
- Other Associated with Normal/↑ Respiratory Effort
- Other Associated with ↓ Respiratory Effort
Non-Emergent
- ALS
- Ascites
- Uncorrected ASD
- Congenital heart disease
- COPD exacerbation
- Fever
- Hyperventilation
- Interstitial lung disease
- Neoplasm
- Obesity
- Panic attack
- Pleural effusion
- Polymyositis
- Porphyria
- Pregnancy
- Rib fracture
- Spontaneous pneumothorax
- Thyroid Disease
- URI
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
- Aspiration is a risk factor for pulmonary abscess formation
Management
- Aspiration pneumonitis
- Suction upper airway if aspiration is witnessed
- Caused by aspiration of gastric contents. Usually resolves in 24-48 hrs w/o treatment
- Antibiotics
- Only recommended if symptoms persist >48hr
- Same as those for community-acquired aspiration pneumonia below
- Aspiration pneumonia
- Treat same as CAP
- Antibiotics:
- Monotherapy: Levofloxacin 750 mg daily OR moxifloxacin 400 mg daily
- or combination therapy: ampicillin-sulbactam 3 g q6h OR ceftriaxone 2 g daily PLUS azithromycin 500 mg daily OR clarithromycin 500 mg BID.
- Routinely adding anaerobic coverage beyond the standard empiric treatment for community-acquired pneumonia is no longer recommended unless lung abscess, empyema, healthcare-associated, periodontal disease, or SBO:[1] Metronidazole 500 mg q8h OR clindamycin 600 mg q8h
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
- ↑ Metlay JP, Waterer GW, Long AC, et al. Diagnosis and treatment of adults with community-acquired pneumonia. An official clinical practice guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019;200(7):e45–e67.