Aspiration pneumonia is diagnosed based on clinical signs or symptoms of pneumonia in a person with a history or risk factors for aspiration.
Sputum or tracheal Gram stain reveals mixed flora.
Infection usually involves the dependent lung lobe.
Complications of disease include lung abscess and empyema.
Aspiration pneumonia results from inhalation of oropharyngeal contents into the lower airways that leads to lung injury and resultant bacterial infection. It commonly occurs in patients with altered mental status who have an impaired gag or swallowing reflex.
The bacteriology and presentation of aspiration pneumonia have changed over the past five decades. Older studies characterized an anaerobic pleuropulmonary syndrome, with necrotizing pneumonia, putrid sputum, and abscess formation as a result of the presence of anaerobic bacteria. More recent literature suggests that aspiration pneumonia resulting from anaerobic bacteria is less common than previously thought, and often is not distinct from pneumonia caused by aerobic bacteria. There is debate on whether aspiration pneumonia represents a distinct entity from typical pneumonia, or whether it is one end of the spectrum of pneumonia syndromes. There is no definition that separates patients with aspiration pneumonia from typical pneumonia. Typical pneumonia can also occur from microaspiration of oronasopharyngeal contents, and can present with similar microbiology and clinical course as aspiration pneumonia, as well as needing similar treatment.
History and exam
Key diagnostic factors
Other diagnostic factors
- pleuritic chest pain
- foul-smelling breath
- frothy or purulent sputum
- history of vomiting
- chemoradiation for head and neck cancers
- altered mental status
- swallowing dysfunction
- gastrointestinal disease
- intubation or tracheostomy tube
- older age
- poor oral hygiene
- feeding tube
- recumbent position
1st investigations to order
- O2 saturation
- sputum Gram stain
- sputum culture
Investigations to consider
- point-of-care lung ultrasound
- Aspiration pneumonitis
- Pulmonary edema
- 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
- Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: application to healthy patients undergoing elective procedures
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