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 underwent laceration of the left hemidiaphragm. Arterial blood gas levels, pulmonary artery wedge pressure, cardiac output and arterial blood pressure were measured. The stomach was then placed above the diaphragm. The initial measurements were repeated, and displacement of the stomach above the diaphragm (S/D) was measured. The animals were divided into two groups: group 1, eight animals breathing 80% oxygen spontaneously and group 2, eight animals receiving IPPV. Initially in group 2 there was only a small decrease in mean (+/- SD) arterial oxygen tension from 484 +/- 34 mm Hg to 424 +/- 20 mm Hg (other parameters were unchanged). In group 1, gastric herniation.produced a further fall in arterial oxygen tension to 308 +/- 10 mm Hg at 1 hour, a rise in arterial carbon 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 occurred 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 carbon dioxide tension and 7.38 +/- 0.05 for pH after IPPV. Similar changes 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 decreased from 6.0 +/- 0.2 cm to 1.1 +/- 0.5 cm after 1 hour in group 2. The authors conclude that diaphragmatic rupture produces cardiorespiratory changes, but these are small in the absence of gastric herniation. IPPV effectively reduces gastric herniation and corrects the cardiorespiratory abnormalities and is therefore a valuable temporary treatment until a definitive operation can be done.