Pneumoperitoneum associated with artificial ventilation.

Four adults injured in serious road-traffic accidents developed pneumoperitoneum after artificial ventilation. No case could be attributed to injury or to perforation of a hollow viscus in the belly, but doubt about this in one patient resulted in exploratory laparotomy. In three patients the origin of intraperitoneal air was considered to be leakage through minute ruptures in alveoli subjected to the stress of artificial ventilation, with air tracking to the mediastinum, pleural space, subcutaneous tissues of the neck and chest, and peritoneal cavity. The fourth patient later developed herniation of the stomach through a rupture in the diaphragm, the presence of a pneumothorax on the same side suggesting direct passage of air through the diaphragm. Pneumoperitoneum induced by artificial ventilation is probably more common than reports suggest and should be distinguished clinically and radiologically from that caused by rupture or perforation of a hollow viscus. This will reduce the number of needles laparotomies performed on patients who are already seriously ill.