Incidence and clinical effects of intra-abdominal hypertension in critically ill patients

Objective: The objective of this study was to determine the epidemiology and outcomes of intra-abdominal hypertension in a heterogeneous intensive care unit population. Design: This was a prospective cohort study. Setting: This study was conducted at a medical-surgical intensive care unit in a university hospital. Patients: Study patients included all those consecutively admitted during 9 months, staying > 24 hrs, and requiring bladder catheterization. Measurements and Main Results: On admission, epidemiologic data and risk factors for intra-abdominal hypertension were studied; then, daily maximal and mean intra-abdominal pressures (IAP(max) and IAP(mean)), abdominal perfusion pressure, fluid balances, filtration gradient, and sequential organ failure assessment score, were registered. IAPs were recorded through a bladder catheter every 6 hrs until death, discharge, or along 7 days. Intra-abdominal hypertension was defined as IAP > 12 mm Hg. Abdominal compartment syndrome was defined as IAP >= mm Hg plus >= 1 new organ failure. Main outcome measure was hospital mortality. of 83 patients, considering IAP(max), 31% had intra-abdominal hypertension on admission and another 33% developed it after (23% and 31% with IAP(mean)). Main risk factors were mechanical ventilation, acute respiratory distress syndrome, and fluid resuscitation (relative risk, 5.26, 3.19, and 2.50, respectively). Patients with intra-abdominal hypertension were sicker, had higher mortality (53% vs. 27%, p =.02), and consistently showed higher total and renal sequential organ failure assessment score, daily and cumulative fluid balances, and lower filtration gradient. Non-survivors had higher IAP(max), IAP(meaw) and fluid balances and lower abdominal perfusion pressure. Abdominal compartment syndrome developed in 12%; 20% survived. Logistic regression identified IAP(max) as an independent predictor of mortality (odds ratio, 1.17; 95% confidence interval, 1.05-1.30; p =.003) after adjusting with Acute Physiology and Chronic Health Evaluation 11 and comorbidities (odds ratio, 1.15; 95% confidence interval, 1.06-1.25; p =.001; and odds ratio, 2.68; 95% confidence interval, 1.27-5.67; p =.013, respectively). Models with IAP(mean) and abdominal perfusion pressure also performed well. Areas under receiver operating characteristic curves were 81 and 83. Conclusions: Intra-abdominal hypertension, diagnosed either with IAP(max) or IAP(mean), was frequent and showed an independent association with mortality. Intra-abdominal hypertension was significantly associated with more severe organ failures, particularly renal and respiratory, and a prolonged intensive care unit stay.