Phosphorylcholine coating may limit thrombin formation during high-risk cardiac surgery: A randomized controlled trial

Background. During cardiopulmonary bypass, blood contact with the large nonendothelial surfaces of the extracorporeal circuit induces activation and consumption of platelets and plasma coagulation factors. Phosphorylcholine (Pc) coating of oxygenators has been designed to improve surface biocompatibility. We evaluated the effects of a Pc-coated oxygenator on blood coagulation in patients undergoing high-risk open heart surgery and receiving tranexamic acid. Methods. Thirty-nine patients undergoing reoperative valvular or combined procedures were randomized to the use of an oxygenator treated with Pc coating (Pc group) or of a standard oxygenator (control group). Platelet count, soluble CD40 ligand, fibrinogen, antithrombin, D-Dimer, prothrombin fragment 1.2 (F1.2), and free plasma hemoglobin levels were measured at baseline, at aortic unclamping, and at arrival in the intensive care unit. Results. Postoperative bleeding, need for blood products, and clinical outcomes were similar in the two groups. At unclamping, F1.2, a marker of in vivo thrombin formation, increased to a greater extent in control patients than in Pc patients (p = 0.02), and in the latter group of patients was positively correlated with aortic cross-clamp times (r = 0.70). Relative to baseline values, the percent decrease in platelet count, fibrinogen, and antithrombin levels was not significantly different in Pc patients and in control patients after adjustment for multiple comparisons, but the percent decrease in platelet counts was negatively correlated with F1.2 levels in the entire series of patients (r = -0.62, p <0.0001). All the evaluated parameters were similar in the two groups of patients at arrival in the intensive care unit. Conclusions. For patients undergoing high-risk open heart surgery and receiving tranexamic acid, a phosphorylcholine-coated oxygenator may reduce intraoperative thrombin formation and the associated consumption of platelets, fibrinogen, and antithrombin.