CARDIOPULMONARY EFFECTS OF RAISED INTRAABDOMINAL PRESSURE BEFORE AND AFTER INTRAVASCULAR VOLUME EXPANSION

The cardiopulmonary effects of acutely elevated intra-abdominal pressu re (IAP) were studied in a porcine model to help define more clearly I AP effects in patients with trauma, IAP was increased in six anestheti zed swine by intra-abdominal instillation of isotonic ethylene glycol up to an IAP of 25 mm Hg above baseline, Systemic and pulmonary hemody namic parameters were measured, as well as the effects on bladder pres sure, pleural pressure, and pulmonary function, At IAP of 25 mm Hg abo ve baseline, intravascular volume expansion with saline was administer ed to return the cardiac index (CI) to baseline, Raising IAP correlate d with measured bladder pressures (r = 0.9, p = 0.001), At IAP of 25 m m Hg, CI was significantly decreased (p < 0.05, analysis of variance ( ANOVA); 3.6 +/- 0.3 vs, 2.2 +/- 0.3 L/min/m(2)); whereas wedge, pulmon ary arterial, and pleural pressures were all elevated (p < 0.05, ANOVA ), However, transarterial wedge pressure (wedge - pleural pressure) de clined nonsignificantly with increasing IAP, Raised IAP caused impaire d pulmonary function with a decreased (p < 0.05, ANOVA) Pao, and incre ased (p < 0.05, ANOVA) Paco(2). Despite the elevated wedge pressure, f luid resuscitation returned CI to baseline, These data clarify the hem odynamic changes associated with raised LAP and indicate that care mus t be taken in interpreting hemodynamic measurements to determine intra vascular fluid status in patients with elevated IAP.