The effects of positive airway pressure and intra-abdominal pressure in diaphragmatic rupture.

Arterial blood gases (80% oxygen), intraperitoneal pressure (IP), stomach position relative to the diaphragm (S/D by fluoroscopy), blood pressure, and cardiac output were monitored in 16 anaesthetized New Hampshire piglets with a 12 cm laceration of the left hemidiaphragm. Group I (8 animals) were spontaneously breathing. Group II (8 animals) had a pneumatic antishock garment (PASG) inflated to an IP of 40 torr for 15 mins followed by positive pressure ventilation (PPV) of 20 cm H2O for 15 min and PPV of 40 cm H2O (PPV-40) for 30 more minutes. All Group I animals survived. Three Group II animals died by 15 min after PASG inflation. Seven Group I animals showed no displacement of the stomach above the diaphragm. Blood pressure, cardiac output, and blood gases remained unchanged in Group I compared to baseline with pO2 varying from 436 +/- 44 torr to 417 +/- 31 torr, pCO2 from 38 +/- 1 torr to 39 +/- 1 torr, and pH 7.4 +/- 0.02. Blood pressure in Group I was 109 +/- 3 torr at baseline to 110 +/- 2 torr at 60 mins, and baseline cardiac output was 3.9 +/- 0.2 L/min and 3.8 +/- 0.2 L/min at 60 min. Group II animals had a baseline arterial pO2 of 423 +/- 15 torr and 100 +/- 15 torr at 15 min after PASG. With PPV-20 arterial pO2 increased to 178 +/- 13 torr and further increased to 230 +/- 9 torr at PPV-40.(ABSTRACT TRUNCATED AT 250 WORDS)