Renal failure and abdominal hypertension after liver transplantation: determination of critical intra-abdominal pressure

There is growing interest in measuring intra-abdominal pressure (IAP) in postsurgical and critically ill patients because increased pressure can impair various organs and functions. The aim of this study was to evaluate the effect of different IAP levels on the postoperative renal function of subjects undergoing orthotopic liver transplantation. IAP was measured every 8 hours with the urinary bladder pressure method for at least 72 hours after surgery. At the end of the study, the patients were classified on the basis of their IAP values: < or = 18 mm Hg (group A), 19 to 24 mm Hg (group B), > or = 25 mm Hg (group C). The three groups were compared in terms of the incidence of acute renal failure (defined as blood creatinine > 1.5 mg/dL or an increase in the same of > 1.1 mg/dL within 72 hours of surgery), hourly diuresis, blood creatinine, the filtration gradient, hemodynamic variations, and outcome. The incidence of renal failure was higher among the subjects in group C (P < .05 versus group A and < .01 versus group B), who also had higher creatinine levels (P < .01), a greater need for diuretics (P < .01) and a worse outcome (P < .05). Receiver Operator Characteristic curve analysis showed that an abdominal pressure of 25 mm Hg had the best sensitivity/specificity ratio for renal failure. An intra-abdominal pressure of > or = 25 mm Hg is an important risk factor for renal failure in subjects undergoing liver transplant.