pulmonary aspiration; foreign body aspiration

Introduction

Inspiratory suction into the airways of fluid or foreign body, such as saliva or vomitus.

Etiology

• aspiration of gastric contents
• aspiration of saliva or ingested substances
• aspiration of foreign body

Risk factors:

• impaired consciousness
• impaired pharyngeal or laryngeal function (see swallowing)
  • myopathy
  • neuropathy
  • immediately postextubation
• increased intragastric pressure or volume
  • nausea/vomiting
  • ileus
  • tube feeding*
• esophageal disorders that predispose to reflux

*tube feeding does not reduce risk of aspiration; it increases risk

Epidemiology

• most healthy people aspirate without any important clinical consequences

Pathology

• aspiration of inert liquids or foreign bodies
  • airway obstruction
  • acute respiratory distress
  • hypoxemia
• aspiration pneumonitis
  • low pH (< 2.5) of aspirated gastric contents
  • large volume of aspirate
• aspiration pneumonia
  • occurs in 40% of patients who aspirate
  • most commonly 2-5 days after aspiration event
  • mixed aerobic/anaerobic organisms

Clinical manifestations

• sudden onset dyspnea, monophonic wheeze, history of stroke, normal chest X-ray suggests foreign body aspiration

Diagnostic procedures

• fiberoptic bronchoscopy if aspiration of foreign body suspected*
• swallowing evaluation of uncertain benefit
• bedside water-swallow testing
  • single sips of <= 20 mL: sensitivity, 63%-71%; specificity, 90%
  • consecutive sips (100 mL without stopping): sensitivity, 91%; specificity, 53%
  • progressively increasing swallowing volume: sensitivity, 86%; specificity, 65%

* sudden onset dyspnea, monophonic wheeze, history of stroke, normal chest X-ray

Radiology

• chest X-ray
  • aspiration of inert liquids or foreign bodies
  • pulmonary infiltrates
  • atelectasis
  • lobar collapse
• chest CT (image of chicken vertebrae)

Differential diagnosis

• universal choking sign may be observed if airway obstruction is in the upper airway

Management

• aspiration of inert liquids or foreign bodies
  • bronchoscopy (early)
• aspiration pneumonitis (see aspiration pneumonitis)
  • withold antibiotics until evidence of bacterial superinfection except in association with:
    • intestinal obstruction
    • gingivitis or periodontitis (severe)
    • immunocompromised host
• aspiration pneumonia (see aspiration pneumonia)
  • mixed aerobic/anaerobic organisms
    • clindamycin or penicillin G
    • coverage for hospitalized patients should include:
      • Staphylococcus aureus
      • gram negative bacteria
• general
  • nothing by mouth NPO
  • nasogastric tube
  • swallowing study if indicated

More general terms

• lung disease
• aspiration
• sign/symptom

More specific terms

• meconium aspiration

Additional terms

• aspiration pneumonia
• aspiration pneumonitis (Mendelson's syndrome)
• esophagus
• foreign body
• gastroesophageal reflux disease (GERD)
• larynx
• pharynx
• swallowing (deglutition)
• trachea