Aspiration Pneumonia

Aspiration pneumonia results from inhalation of oropharyngeal contents leading to lower respiratory tract infection.

• The usual site for an aspiration pneumonia is the right lung. Aspirated material enters the lower lobes when the patient is standing.
• If the patient is supine then the aspirated material will enter the apical segment of the lower lobes or the posterior segment of the upper lobes.

Aspiration pneumonitis is caused by chemical damage due to acute inhalation of regurgitated gastric contents.

• Depressed gag reflex: anaesthesia (e.g. Mendelson syndrome), bulbar palsy
• Transient period of impaired consciousness: alcoholic abuse, seizures, head injury, drug overdose
• Gastro-oesophageal reflux¹
• Oesophageal stricture
• Tracheo-oesophageal fistula
• Common complication of nasogastric feeding tube.²

• Common and may account for up to15% of patients with community-acquired pneumonia.
• More common in men, young children and the elderly.

• Non-specific symptoms, e.g. fever, headache, nausea, vomiting, anorexia, myalgia, weight loss
• Cough
• Dyspnoea
• Pleuritic chest pain
• Purulent sputum
• Signs may include tachycardia, tachypnoea, decreased breath sounds and dullness to percussion over areas of consolidation, pleural friction rub.
• Severe infection may lead to hypoxia and septic shock.

Other causes of respiratory distress, including:

• Other causes of pneumonia
• Bronchiolitis
• Croup
• Epiglottitis
• Foreign body in respiratory tract
• Asthma
• Cardiovascular disease.

• Blood count: neutrophil leucocytosis
• Electrolytes and renal function: dehydration, electrolyte imbalance
• Blood culture
• Blood gases
• Culture of sputum:
  Many aspiration pneumonias are mixed aerobic-anaerobic infections.³
  • In patients with bacterial aspiration pneumonia may show organisms normally resident in the pharynx, e.g. Bacteroides, Fusobacterium, and Peptococcus.
• Chest x-ray:
  • Right middle and lower lung lobes are the most common sites.
  • Aspiration when upright may cause bilateral lower lung infiltrates.
  • Right upper lobe often shows consolidation in alcoholics who aspirate in the prone position.
• Lung CT and bronchoscopy only very occasionally required.

• Mechanical obstruction: removal of object normally by bronchoscopy.
• Tracheal suction if seen early.
• Intubation with positive pressure ventilation may be required.
• Bacterial infection of lower airways:
  • Initial empirical antibiotic therapy while awaiting culture results.
  • Antimicrobial therapy should be based on patient characteristics, the setting in which aspiration occurred, the severity of pneumonia, and available information regarding local pathogens and resistance patterns.³
  • Community acquired aspiration pneumonia is often initially treated with amoxicillin plus metronidazole Hospital acquired aspiration pneumonia may initially be treated with a cephalosporin, gentamicin and metronidazole.
• The role of steroids is uncertain and not of proven benefit.

• Untreated, bacterial aspiration pneumonia may progress to lung abscess or bronchiectasis.
• Acute respiratory distress.

Depends on the underlying cause, general well-being of patient, presence of complications, speed of diagnosis and effective treatment.

• Keep the head of the bed at a 30 degree angle: reduces the risk or aspiration pneumonia in those at risk.
• Nasogastric feeding for at risk patients, e.g. poor gag reflux, dysphagia.