HEMORRHAGE LOWERS THE THRESHOLD FOR INTRAABDOMINAL HYPERTENSION-INDUCED PULMONARY DYSFUNCTION

Background: Intra-abdominal hypertension has been associated with pulm onary and cardiac dysfunctions. We have noted in the clinical scenario of hemorrhagic shock and resuscitation that avoidance of even moderat e levels of increased intra-abdominal pressure, using prophylactic dec ompression, improves outcomes when compared with patients who were dec ompressed when intra-abdominal pressures went over 20 cm H2O. We hypot hesized that prior hemorrhage and resuscitation exacerbates the cardio pulmonary dysfunction associated,vith intraabdominal hypertension. Met hods: Ten anesthetized pigs underwent placement of arterial and pulmon ary artery catheters and a Silastic intra-abdominal catheter for measu ring and manipulating intra-abdominal pressure, Group 1 animals (n = 5 ) were subjected to increasing intra-abdominal pressures at 10 mm Hg i ncrements up to a level of 40 mm Hg, Group 2 animals (n = 5) were expo sed to a severe hemorrhage and resuscitation before the increasing int ra-abdominal pressure protocol. Results: Compared with baseline, hemor rhage and resuscitation caused a significant deterioration in cardiac output at intraabdominal pressures of 10 mm Hg and above, Oxygenation was reduced at 30 and 40 mm Hg, These changes were not seen in group 1 animals, A significant difference was found between groups 1 and 2 in VT, Paco(2), and Paco(2)/Flo(2) ratio at an intraabdominal pressure o f 20 mm Hg. This difference was not seen at lower or higher pressures. Conclusions: Prior hemorrhage and resuscitation caused an earlier dec line in cardiopulmonary function in the setting of increased intra-abd ominal pressure, These data suggest that, when interpreting intra-abdo minal pressures, the clinical scenario must he considered, Prior hemor rhage and resuscitation produce the adverse consequences of intra-abdo minal hypertension at lower pressures than when intra-abdominal hypert ension is the only insult.