Acute respiratory distress syndrome differential diagnosis
ARDS must be differentiated from other diseases that cause hypoxemia and pulmonary infiltrates, such as pulmonary edema, diffuse pneumonia, pulmonary hemorrhage, interstitial lung disease, and radiation pneumonitis.
Differentiating ARDS from Other Diseases
Prior to the development of the Berlin definition, a greater emphasis was placed on excluding other potential illnesses before establishing the diagnosis of ARDS. While it is important to recognize and treat and underlying cause, this search for potential etiologies should not delay any focused efforts to improve oxygenation and ventilation.
- Infectious pneumonia (bacterial, fungal, viral, or parasitic)
- Aspiration pneumonitis (chemical pneumonia)
- Acute eosinophilic pneumonia
- Pulmonary contusion
- Cardiogenic pulmonary edema
- Neurogenic pulmonary edema
- Hypersensitivity pneumonitis
- Pulmonary hemorrhage
On chest x ray, the bilateral, non-cardiogenic pulmonary infiltrates of ARDS may appear similar to those of cardiogenic (hydrostatic) pulmonary edema. Therefore, it is necessary to formally assess cardiac function and volume status if ARDS is suspected but no clear precipitating insult (e.g., sepsis, trauma, toxic inhalation) can be identified. The preferred methods for making this assessment in the ICU are:
- Echocardiography to assess heart function
- Central venous catheterization to measure central venous pressure
- Pulmonary artery (Swan-Ganz) catheterization to measure right-sided heart pressures and pulmonary capillary wedge pressure (a surrogate of left atrial pressure)