Intra-abdominal hypertension in cardiac surgery

The occurrence of intra-abdominal hypertension (IAH), as well as its promoting factors in cardiac surgery, has been poorly explored. The aim of the present study was to characterize intra-abdominal pressure (IAP) variations in patients undergoing cardiac surgical procedures, and to identify the risk factors for IAH in this setting.

All consecutive adult patients requiring postoperative intensive care unit admission for >24 h were enrolled. Demographic data, pre-existing comorbidities, type and duration of surgery, cardiopulmonary bypass (CPB) use and duration, perioperative IAP, organ function and fluid balance were recorded. IAH was defined as a sustained increase in IAP >12 mmHg. Multivariate logistic regression and stepwise analyses identified the baseline and perioperative variables associated with IAH.

Of 69 patients, 22 (31.8%) developed IAH. In the logistic model, baseline IAP, high central venous pressure, vasoactive drugs administration, positive fluid balance, AKI, CPB, total sequential organ failure assessment score and age were all promoting factors for IAH (Hosmer-Lemeshow χ(2) = 7.23; P = 0.843). Baseline IAP, high central venous pressure and positive fluid balance were independent risk factors for IAH in the stepwise analysis. The ROC curve analysis, obtained by plotting the occurrence of IAH vs the IAP baseline value, showed an AUC of 0.75 (SE 0.064; 99% CI 0.62-0.87; P < 0.0001). The best IAP cut-off value was at 8 mmHg (sensitivity 63% and specificity 76%). Considering on- and off-pump surgery groups, fluid balance and vasoactive drugs use were significantly higher in the on-pump group. Linear regression analysis showed a positive correlation (P = 0.0001) between IAP changes and fluid balance only in the on-pump group.

IAH develops in one-third of cardiac surgery patients and is strongly associated with higher baseline IAP values, higher central venous pressure, positive fluid balance, extracorporeal circulation, use of vasoactive drugs and AKI. Determinants of IAH should be accurately assessed before and after surgery, and patients presenting risk factors must be monitored properly during the perioperative period. In this context, the baseline value of IAP may be a valuable and early warning parameter for IAH occurrence.