Pneumoperitoneum and pneumoretroperitoneum. Consequences of positive end-expiratory pressure therapy.

Patients receiving positive end-expiratory pressure (PEEP) therapy should be considered at risk for pneumoperitoneum. In the four patients described, chest roentgenographic demonstration of pulmonary interstitial gas and pneumomediastinum, frequently but not always associated with pneumothorax, preceded the dissection of gas into the abdominal cavity. Neither prompt intubation of the pleural space with reexpansion of the lung in the event of pneumothorax nor decrease in the PEEP applied precluded dissection of gas from the mediastinum into the retroperitoneal and peritoneal spaces. This sequence of roentgenographic events should strongly suggest pneumoretroperitoneum and pneumoperitoneum as a sequela to PEEP therapy rather than a ruptured viscus.