From the Guidelines
Aspiration pneumonitis is diagnosed based on a combination of clinical presentation, history, and diagnostic findings, including a history of witnessed aspiration or risk factors for aspiration, acute onset of respiratory symptoms, characteristic radiographic findings, hypoxemia, and signs of respiratory distress, as outlined in the guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia 1. The key diagnostic criteria include:
- A history of witnessed aspiration or risk factors for aspiration (such as decreased consciousness, dysphagia, or recent anesthesia)
- Acute onset of respiratory symptoms following the aspiration event
- Characteristic radiographic findings (typically infiltrates in dependent lung segments, often right lower lobe)
- Hypoxemia
- Signs of respiratory distress Physical examination may reveal:
- Crackles
- Wheezing
- Decreased breath sounds Laboratory findings often show:
- Leukocytosis
- Arterial blood gases typically demonstrate hypoxemia Bronchoscopy may be performed to:
- Visualize and potentially remove aspirated material
- Help differentiate chemical pneumonitis from subsequent bacterial infection The timing is important - aspiration pneumonitis develops rapidly (within hours) after aspiration, distinguishing it from aspiration pneumonia which develops later (24-72 hours) and involves bacterial infection of the aspirated contents, as noted in the guidelines for the management of adult lower respiratory tract infections 1. Diagnosis is often one of exclusion, ruling out other causes of acute respiratory distress, and the severity can range from mild inflammation to acute respiratory distress syndrome (ARDS) in severe cases, with the clinical course dependent on the volume and nature of the aspirated material, as discussed in the American Thoracic Society documents 1.
From the Research
Diagnostic Criteria for Aspiration Pneumonitis
The diagnostic criteria for aspiration pneumonitis are not universally agreed upon, but several studies provide insight into the clinical features and risk factors associated with this condition.
- Aspiration pneumonitis is often diagnosed based on a combination of symptoms, inflammatory markers, and chest imaging findings 2.
- The presence of one or more risk factors for oropharyngeal aspiration, along with one or more risk factors for oral bacterial colonization, can be used to define aspiration pneumonia 3.
- Aspiration can be inferred if there is witnessed or prior presumed aspiration, episodes of coughing on food or liquids, relevant underlying conditions, abnormalities on videofluoroscopy or water swallow test, and gravity-dependent distribution of shadows on chest imaging 2.
- A clinical algorithm can be used to distinguish between pneumonitis and pneumonia in nursing home residents, with factors such as presenting symptoms and signs, laboratory tests, and severity of illness measures considered 4.
Clinical Features and Risk Factors
Patients with aspiration pneumonitis often have certain clinical features and risk factors, including:
- Older age and frailty 2
- Comorbidities such as malnutrition, smoking, poor oral hygiene, or dry mouth 3
- Witnessed or prior presumed aspiration, episodes of coughing on food or liquids, or relevant underlying conditions 2
- Abnormalities on videofluoroscopy or water swallow test, and gravity-dependent distribution of shadows on chest imaging 2
Diagnosis and Management
The diagnosis of aspiration pneumonitis is often presumptive, based on the patient's general frailty and clinical presentation rather than swallowing function itself 2.
- Treatment for aspiration pneumonia should include antibiotic coverage for oral anaerobes, aerobes associated with community-acquired pneumonia, and resistant organisms depending on the clinical context 5.
- Prevention of aspiration and oral colonization is crucial, with strategies such as improved oral hygiene and positional feeding having mixed results 5, 3.