THE INFLUENCE OF INTERMITTENT POSITIVE-PRESSURE VENTILATION ON THE CARDIORESPIRATORY DYNAMICS OF DIAPHRAGMATIC RUPTURE WITH GASTRIC HERNIATION

To determine the effect of intermittent positive-pressure ventilation (IPPV) on gastric herniation in diaphragmatic rupture, 16 piglets unde rwent laceration of the left hemidiaphragm. Arterial blood gas levels, pulmonary artery wedge pressure, cardiac output and arterial blood pr essure were measured. The stomach was then placed above the diaphragm. The initial measurements were repeated, and displacement of the stoma ch above the diaphragm (S/D) was measured. The animals were divided in to two groups: group 1, eight animals breathing 80% oxygen spontaneous ly and group 2, eight animals receiving IPPV. Initially in group 2 the re was only a small decrease in mean (+/- SD) arterial oxygen tension from 484 +/- 34 mm Hg to 424 +/- 20 mm Hg (other parameters were uncha nged). In group 1, gastric herniation.produced a further fall in arter ial oxygen tension to 308 +/- 10 mm Hg at 1 hour, a rise in arterial c arbon dioxide tension to 49 +/- 4 mm Hg and a decrease in pH to 7.32 /- 0.04. In group 2 similar changes in arterial blood gas levels occur red with gastric herniation, but there was a return to baseline values of 490 +/- 28 mm Hg for arterial oxygen tension, 37 +/- 4 mm Hg for c arbon dioxide tension and 7.38 +/- 0.05 for pH after IPPV. Similar cha nges were seen in blood pressure, cardiac output and pulmonary artery wedge pressure. S/D remained at 6.3 +/- 0.2 cm in group 1 but decrease d from 6.0 +/- 0.2 cm to 1.1 +/- 0.5 cm after 1 hour in group 2. The a uthors conclude that diaphragmatic rupture produces cardiorespiratory changes, but these are small in the absence of gastric herniation. IPP V effectively reduces gastric herniation and corrects the cardiorespir atory abnormalities and is therefore a valuable temporary treatment un til a definitive operation can be done.