Systemic air embolism: does it occur after experimental penetrating lung injury?

Systemic arterial air embolization following penetrating injury of the lung has been previously reported. As we had not recognized this complication clinically, we studied this problem in 11 healthy dogs. In each of them, a mock circulation was created by establishing two central external arteriovenous shunts with transparent plastic tubing in which air bubbles could be seen. Also, a Doppler flow detector capable of sensing intravascular air was attached to a carotid artery. Systemic arterial and pulmonary capillary wedge pressures were recorded, and a standard lung laceration was produced. In 5 of the dogs, in addition, tension pneumothorax was induced by injection of air into the pleural space. The dogs were monitored for intravascular air for 15 minutes before and after the induction of hypotension by withdrawal of blood from the shunts. In no animal was air seen in the shunts, nor was there the characteristic deflection of the Doppler seen with intravascular air, although the preparation was sensitive to the detection of as little as 1 ml. of air injected into the left atrium. These observations lead us to question whether arterial air embolism occurs with penetrating pulmonary trauma in man.