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Aspiration Pneumonia

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Aspiration Pneumonia, Pneumonitis due to inhalation of food or vomitus, Aspiration Pneumonitis

  • Definitions
  1. Aspiration Pneumonia
    1. Pneumonia due to food, liquid or gastric contents aspirated into the upper respiratory tract
  2. Aspiration Pneumonitis (chemical pneumonitis)
    1. Chemical aspiration of acidic gastric contents
      1. Degree of injury increases with gastric acidity (significant if gastric pH<2.5)
    2. With normal gastric acidity, Stomach contents are typically sterile
      1. However, not sterile in Antacid use, enteral feeding, Gastroparesis, poor Dentition and Small Bowel Obstruction
  • Epidemiology
  1. Represents <15% of all Community Acquired Pneumonia
  • Risk Factors
  1. Underlying Neurologic disease or Impairment (esp. depressed gas reflex)
    1. Cerebrovascular Accident
    2. Dementia
    3. Seizure
    4. Alcohol Intoxication
    5. Obtunded
  2. Esophageal dysfunction
  3. Anesthesia complication
  4. Microaspiration in Sleep Apnea
  5. Poor Dentition or severe gum disease
  1. Bacteroides
  2. Peptostreptococcus
  3. Microaerophilic Streptococcus
  4. Fusobacterium
  5. Nocardia
  • Pathophysiology
  1. Necrotizing infection may lead to cavitation
  2. Affects dependent lung lobes
  • Symptoms
  1. Low grade fever
  2. Weight loss
  3. Productive cough with foul smelling Sputum
  • Labs
  1. Sputum Gram Stain unreliable
    1. Typically demonstrates mixed oral flora and many PMNs
  2. Sputum Culture unreliable
  • Imaging
  1. Chest XRay (often negative initially)
    1. RadAspirationPneumoniaPaMedPix6057.jpgFrom MedPix with permission.
    2. RadAspirationPneumoniaLateralMedPix6058.jpgFrom MedPix with permission.
    3. Typically involves dependent lung tissue
  • Management
  • General
  1. Initial aspiration event results in chemical pneumonitis (not Pneumonia)
    1. When this is witnessed (e.g. under anesthesia, Endotracheal Intubation), do not immediately start antibiotics
    2. Await the development of Pneumonia (fever, symptoms) to institute antibiotics
      1. Empiric antibiotic prophylaxis after witnessed aspiration results in worse outcomes (e.g. Antibiotic Resistance)
      2. Consider early antibiotics in Antacid use, enteral feeding, Gastroparesis and Small Bowel Obstruction
  2. Antibiotics
    1. Typical Pneumonia organisms are more common than Anaerobes even in patients at aspiration risk
      1. Consider starting with typical Community Acquired Pneumonia Management
      2. However, start with anaerobic coverage if poor Dentition or gum disease
      3. Add anaerobic coverage if failure to respond to initial antibiotics
    2. Antibiotic course for up to 3-4 weeks
    3. Extend antibiotic course up to 2-3 months for Lung Abscess
  • Management
  • Oral Antibiotics
  1. First-Line
    1. Clindamycin 300-450 mg orally three times daily
    2. Moxifloxacin 400 mg once daily
  2. Alternative
    1. Amoxicillin-Clavulanate 875 orally twice daily
  • Management
  • Parenteral Antibiotics
  1. First Line
    1. Ceftriaxone 1 g IV every 24 hours AND Metronidazole 500 mg IV every 6 hours (or 1 g IV every 12 hours) OR
    2. Ampicillin-Sulbactam 3 g IV every 6 hours
  2. Alternative
    1. Piperacillin-Tazobactam (Zosyn) 3.375 g IV every 6 hours OR
    2. Ertapenem 1 g IV every 24 hours
  • Prevention
  1. Evaluate with Swallowing Exam
  2. Dysphagia Diet for moderate to severe Dysphagia
  • Prognosis
  • Predictors of worse outcomes
  1. Lower pH (<2.5)
  2. Larger volume aspiration (>25 ml)
  3. Particulate matter aspirated (e.g. food)
  4. Bacterial contamination (esp. Anaerobic Bacteria)
  • References
  1. (2019) Presc Lett 26(9):50
  2. Swadron (2019) Pulmonology 2, CCME Emergency Medicine Board Review, accessed 6/16/2019
  3. Gilbert (2016) Sanford Antimicrobial, accessed IOS app 12/6/2016
  4. Lomotan (1997) Postgrad Med 102(2):225-31 [PubMed]
  5. Sasaki (1997) Intern Med 36(12):851-5 [PubMed]