Alternative perioperative anticoagulation monitoring during cardiopulmonary bypass in aprotinin-treated patients.

Monitoring of anticoagulation during cardiopulmonary bypass by means of the activated coagulation time (ACT) has become questionable due to the prolongation in the clotting time of patients receiving aprotinin. Because the celite-based ACT only indicates intrinsic coagulation, and sufficient anticoagulation is needed to also prevent extrinsic coagulation, the ACT may not be reliable. Three different clotting times, the celite-based ACT, the kaolin-based activated coagulation time (AKT) and the high-dose thrombin time (HITT), were compared in a prospective, double-blind, placebo-controlled study of 20 patients who were to undergo cardiopulmonary bypass. As expected, neither the kaolin-based assay nor the high-dose thrombin time was influenced by aprotinin, whereas the celite-based ACT was significantly prolonged in aprotinin-treated patients as compared to control patients (P < 0.05). This study confirms that both kaolin-based and thrombin-based tests provide a reliable means of determining the degree of heparinization in the presence of aprotinin during cardiopulmonary bypass.