Circuits with surface modifying additive alter the haemodynamic response to cardiopulmonary bypass

Objective: Blood contact with synthetic surfaces during cardiopulmonary byp ass (CPB), inevitably results in the activation of a variety of interrelate d pathways of inflammation and coagulation that may contribute to postopera tive complications in cardiac surgery patients. The objective of this trial was to evaluate clinical events and complement activation related to the u se of a novel biomaterial, into which a surface modifying additive had been incorporated into the polymer used to prepare the bypass circuit. Methods: A prospective, double-blind trial was carried out with 34 patients randomi zed to surgery, with either a standard circuit or a circuit treated ('tip t o tip') with the surface modifying additive. Variables recorded included pe rioperative haemodynamics, volume replacement, ai-agonist and inotrope use. Terminal complement complex (SC5b-9) was measured using an ELISA. Results: Upon initiation of bypass, there was a decrease in mean arterial pressure (MAP) in the control group, not seen in the test group (P = 0.0005, ANOVA). There was a decrease in the total volume of replacement fluid given intrao peratively in the test group as compared with the control group (total plus prime; control 5.3 +/- 1.2 L, test 4.4 +/- 1.9 L, P = 0.03, Mann-Whitney t est). There was a trend to decreased need for inotrope infusion in the test group after CPB (test 1/17, control 6/17, Fisher exact test; P = 0.085). N o difference was seen in the generation of terminal complement complex betw een the groups either during or after CPB. Conclusions: The decrease in blo od pressure in the control group, upon the initiation of CPB, did not occur in patients undergoing CPB with the circuit prepared with the surface modi fying additive. The decrease in blood pressure was likely associated with t he increase in total administered fluids intraoperatively (approximately 1 1/patient) and perhaps the trend towards higher use of inotropes in the con trol patients as opposed to the test patients. These haemodynamic changes d id not appear to be related to complement activation early in CPB. (C) 1999 Elsevier Science B.V. All rights reserved.