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 > or = 12 mm Hg. Abdominal compartment syndrome was defined as IAP > or = 20 mm Hg plus > or = 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. Nonsurvivors had higher IAP(max), IAP(mean), 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 II 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.