ICU outcomes in adult cardiac surgery patients in relation to ultrafiltration type

Abstract

Ultrafiltration (UF) is used to ameliorate the deleterious effects of cardiopulmonary bypass (CPB) in cardiac surgery patients. There are two different methods; conventional ultrafiltration (CUF), performed during CPB, and modified ultrafiltration (MUF), performed after CPB is finished. It has not been established which is better, and controversy remains regarding the optimal UF strategy. The objective of this study was to evaluate if MUF alone, or combined with CUF, could achieve greater fluid removal and contribute to better postoperative clinical outcomes. Also, the potential technique complications were studied. This was a prospective study which enrolled 125 consecutive adult patients receiving elective cardiac surgery with CPB. We analysed three treatment groups: MUF, CUF and both. Ultrafiltration was performed using a non-pulsatile CPB with a non-occlusive roller pump, Sarns 9000, and a polysulfone ultrafilter, Minntech. We studied pre- and intraoperative data and immediate postoperative clinical outcomes: total amount of drainage, transfusion needs, respiratory outcome, cardiac, renal and neurologic complications. Statistical analysis was performed using SPSS 11.0. All three groups were homogeneous and did not have differences in terms of demographic factors, previous history, risk scores, intervention and operative data. Volume of filtrate removal in the group which applied both techniques was larger than in the CUF or MUF groups alone (2569+/-823 vs 1679+/-651 vs 1398+/-353 ml, respectively, p=0.0001); however, despite this difference, there was no difference in the immediate postoperative fluid balances between the groups (596+/-1244 vs 880+/-1054 vs 986+/-1190 ml, p=0.30). Respiratory parameters and postoperative morbidity data analysed (total amount of drainage, transfusion needs, haemoglobin, acute lung injury, time with inotropes, ventricular failure, cardiogenic shock, neurologic complications and renal failure) were similar in all three groups, without statistical differences. Extubation time (10+/-7 vs 8.9+/-3 vs 9.4+/-7.9 hours, p=0.72) and ICU stay (56.6+/-72 vs 66.5+/-109 vs 44.2+/-25 hours, p=0.43) also were similar between the groups. We did not find any technique complication associated with any patient. In the present study, with adult patients receiving elective cardiac surgery, the combined ultrafiltration group had a larger fluid removal. However, neither type of ultrafiltration nor amount of filtered volume was accompanied by different postoperative ICU clinical outcomes. Ultrafiltration was considered a safe and reliable technique, with no related complications.