Aspiration lung injury.

Aspiration lung injury is caused by a failure of the normal protective mechanisms that prevent aspiration of gastric contents. Prevention measures are focused on preserving these protective mechanisms. There are three components to the lung injury. The first component is mechanical obstruction to airways from particles in the aspirate. Treatment is aggressive pulmonary toilet to restore airway patency. The second component, seen beginning in the first several hours, is a chemical injury to the airways, leading initially to bronchorrhea, airway constriction, and edema. Later, there is a marked increase in the risk of bacteria due to altered lung defenses. Treatment is supportive care. The third component is lung injury due to the inflammatory response. This process can evolve to an adult respiratory distress syndrome pattern. With modulation of lung inflammation (currently being developed), morbidity and mortality rates will decrease.