Clinical features of aspiration pneumonitis

Aspiration pneumonitis refers to chemical injury to the lung parenchyma caused by aspiration of acidic stomach contents. In patients with poisoning, altered conscious state is an important risk factor for aspiration pneumonitis (see Risk factors for aspiration pneumonitis). Aspiration pneumonitis significantly increases mortality in patients with poisoning—8.5% mortality in those with aspiration compared with 0.4% mortality in those without—and increases hospital length of stay by almost tenfold.

The severity of aspiration pneumonitis ranges from mild symptoms, such as cough or wheeze, to severe acute respiratory distress syndrome. Symptom onset is rapid (usually within hours of aspiration) and, in most patients, symptoms improve quickly (usually within 24 to 48 hours).

Aspiration pneumonitis may cause respiratory failure, requiring oxygen and respiratory support. It is rarely associated with bacterial colonisation and infection, although pneumonia can develop in the days following aspiration in a patient with aspiration pneumonitis.

It is important to distinguish between aspiration events, aspiration pneumonitis and aspiration pneumonia (see What is aspiration pneumonia?) because antibiotic therapy is only indicated for aspiration pneumonia.