Intra-abdominal hypertension and acute renal failure in critically ill patients

To investigate the relationship between intra-abdominal hypertension (IAH) and acute renal failure (ARF) in critically ill patients.

Prospective, observational study in a general intensive care unit.

Patients consecutively admitted for >24 h during a 6-month period.

None.

Intra-abdominal pressure (IAP) was measured through the urinary bladder pressure measurement method. The IAH was defined as a IAP > or =12 mmHg in at least two consecutive measurements performed at 24-h intervals. The ARF was defined as the failure class of the RIFLE classification. Of 123 patients, 37 (30.1%) developed IAH. Twenty-three patients developed ARF (with an overall incidence of 19%), 16 (43.2%) in IAH and 7 (8.1%) in non-IAH group (p<0.05). Shock (p<0.001), IAH (p=0.002) and low abdominal perfusion pressure (APP; p=0.046) resulted as the best predictive factors for ARF. The optimum cut-off point of IAP for ARF development was 12 mmHg, with a sensitivity of 91.3% and a specificity of 67%. The best cut-off values of APP and filtration gradient (FG) for ARF development were 52 and 38 mmHg, respectively. Age(p=0.002), cumulative fluid balance (p=0.002) and shock (p=0.006) were independent predictive factors of IAH. Raw hospital mortality rate was significantly higher in patients with IAH; however, risk-adjusted and O/E ratio mortality rates were not different between groups.

In critically ill patients IAH is an independent predictive factor of ARF at IAP levels as low as 12 mmHg, although the contribution of impaired systemic haemodynamics should also be considered.