Definition:
Aspiration pneumonia is an inflammation of the lungs and bronchial tubes caused by inhaling foreign material. This may progress to form lung abscess.

Discussion:
Aspiration of foreign material (including stomach fluids) into the lung can be a result of disorders that affect normal swallowing, esophageal stricture, gastroesophageal reflux, or decreased or absent gag reflex (in unconscious, or semi-conscious individuals). Old age, dental problems, sedatives, anesthesia, coma, and drug or alcohol abuse could also be contributing factors. The more acidic the material aspirated, the greater the degree of chemical injury to the lungs. Aspiration of gastric contents is one of the leading causes of adult respiratory distress syndrome (ARDS: flooding of the lungs with fluid). The injured lungs can become infected with either anaerobic bacteria or aerobic bacteria. Bacteria associated with gingivitis and dental decay are frequently cultured from lung abscess aspirates. A collection of pus forms in the lung from leukocytes that have migrated to the area in response to chemical mediators of inflammation and microorganisms causing the infection. A protective membrane may form around the abscess (fibrosis). Progressive fibrosis leads to lung abscess (incidence of pneumonia with lung abscess is 6 per 100,000).

Prevention:

Symptoms: Chest X-Ray: Lung Abscess Diagnosis:
  • fever present for 2 weeks or longer, chills
  • weight loss
  • fatigue
  • cough
    • with foul-smelling sputum
    • with sputum containing pus or blood
    • with greenish sputum
  • shortness of breath, chest pain
  • hemoptysis
  • bluish discoloration of the skin caused by lack of oxygen
  • rapid pulse (heart rate)
  • wheezing
  • rales
  • abnormal (high pitched) breathing sounds (may occur)
  • clubbing, nail abnormalities, bone and joint swelling/tenderness
  • Physical Examination
    • crackling chest sounds
    • bronchoscopy
    • chest X-ray (see cavitation circled in blue at right)
  • Chemistry Lab
    • arterial blood gas
  • Hematology Lab
    • a CBC
  • Microbiology Lab
    • blood culture
    • lung needle biopsy with culture
    • sputum culture
For hospital-acquired infections, aspiration pneumonia is almost always Staphylococcus aureus or a Gram-negative bacillus.
Treatment:
Disease management includes control of the infection by antibiotic therapy until chest X-rays improve. Hospitalization may be necessary depending upon the severity of disease. Endotracheal intubation may be required to keep the airway open and a respirator used to deliver oxygen directly to the lungs. Secretions that build up in the lungs must be suctioned away to keep the airway clear. Antibiotics to treat infection and bronchodilators to keep the airway open are often indicated. Chest tube placement for drainage of the pleural space may be necessary to control the infection.

Prognosis:
The outcome depends on the severity of the pneumonia. If acute respiratory failure develops prolonged illness or death may be the outcome. Complete recovery may take as long as 6 to 12 months.

Complications:

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Author: Mary T. Johnson, Ph.D. All material Copyright © 1997-2003, Indiana University School of Medicine.