Adult aspiration pneumonia.

Aspiration pneumonia occurs in many clinical situations and has far-reaching pulmonary consequences. The chest radiograph may suggest or support the diagnosis. Aspiration of gastric contents leads to exudation of fluid into air spaces, causing an alveolar infiltrate. Although its radiographic pattern may suggest pulmonary edema, aspiration of gastric contents can be distinguished by a normal pulmonary capillary wedge pressure. Aspiration of particulate matter causes airways obstruction and atelectasis. Most commonly there is a shifting mixed infiltrate in the lower lobes.