Hemostatic effects of low-dose protamine following cardiopulmonary bypass

Twenty-eight patients undergoing cardiac surgery were prospectively studied and were assigned to two groups. The patients received 0.8- (Group L) or 2 .0-fold (Group H) dose of protamine for the neutralization after cardiopulm onary bypass (CPB) which was determined by Hepcon HMS(R) assay system in wh ich the reagent chamber containing the concentration of protamine that comp letely neutralized the heparin had the shortest clotting time. Mean dose of protamine was 1.60 +/- 0.50 mg kg(-1) in Group L, and 3.56 +/- 1.48 mg kg( -1), respectively. Activated clotting times (ACT) were comparable between t he two groups through this study period. In Group H, platelet counts signif icantly decreased to 69% of that before protamine administration, and plasm a platelet factor 4 level significantly increased to approximate 2-fold of that before protamine administration just after protamine administration, r espectively. However, these phenomena were not observed in Group L. In addi tion, these hemostatic changes occurred transiently just after protamine ad ministration. We conclude that the low-dose protamine may prevent transient platelet depletion following Cpa. Low-dose protamine can neutralize antico agulation effect of heparin sufficiently and may mitigate protamine-induced platelet dysfunction. Am. J. Hematol. 64:112-115, 2000. (C) 2000 Wiley-Lis s, Inc.