BACKGROUND: The incidence and clinical relevance of increased intraabdominal pressure after orthotopic liver transplantation (OLT) has not yet been evaluated despite the finding that occurrence of this condition in postsurgical critically ill patients may impair various organ functions. The aim of this study was to assess whether the occurrence of abdominal hypertension among a population of OLT recipients was an important cofactor producing early postoperative complications. METHOD: This prospective clinical study measured abdominal pressure every 6 hours during the intensive care unit (ICU) stay using the urinary bladder method. A value of >/=25 mm Hg was considered high. Hemodynamic status was simultaneously evaluated and renal function assessed based on the hourly urinary output, and by calculating serum creatinine on postoperative days 2 and 4. Renal failure was defined as a serum creatinine level of >1.5 mg/dL, or an increase in peak of >1 mg/L within 72 hours of surgery. The filtration gradient and patient outcomes were also considered. RESULTS: Intraabdominal hypertension was observed in 32% of cases. The subjects displaying high IAP showed significantly lower artery pressure values (P <.01), but did not differ in terms of central venous pressure or cardiac output. High intraabdominal pressure was more frequently associated with renal failure (P <.01), a lower filtration gradient (P <.001), delayed postsurgical weaning from the ventilation (P <.001), and increased ICU mortality (P <.05). A receiver operator characteristic curve analysis showed that the critical IAP values, namely those with the best sensitivity/specificity, were 23 mm Hg for postoperative ventilatory delayed weaning (P <.05), 24 mm Hg for renal dysfunction (P <.05), and 25 mm Hg for death (P <.01). CONCLUSIONS: Abdominal hypertension occurs frequently after OLT and may be associated with a complicated postoperative course.