Pneumoperitoneum complicating mechanical ventilator therapy.

Subdiaphragmatic air arouses the clinical suspicion of a perforated intra-abdominal viscus. In patients with respiratory failure requiring mechanical ventilation, the retroperitoneal dissection of air from the mediastinum may give rise to radiologic evidence of subdiaphragmatic emphysema. The present report describes four patients with this syndrome. In three of them, a perforated gastric or duodenal ulcer was initially suspected. None of these three patients underwent surgery. Autopsy examinations in two patients revealed extraperitoneal subdiaphragmatic emphysema with secondary rupture into the free peritoneal cavity. The third patient had an uneventful recovery and was discharged from the hospital. In a fourth patient, signs of peritonitis prompted an exploratory laparotomy. No perforation of an intraperitoneal viscus was identified. Upper gastrointestinal contrast roentgenography and peritoneal lavage may help determine the etiology of subdiaphragmatic air in patients undergoing therapy with a mechanical ventilator.