High-dose aprotinin reduces blood loss in patients undergoing total hip replacement surgery

Aprotinin, a proteinase inhibitor, has been reported to reduce blood loss significantly during cardiac surgery. The mechanisms of this effect remain unclear. We studied the effect of aprotinin on blood loss and transfusion requirement during total hip replacement. Potential mechanisms of action and side effects also were investigated.

Forty patients scheduled for primary total hip replacement were randomized to receive, in double-blind fashion, either aprotinin given as a bolus of 2 x 10(6) kallikrein inactivator units (KIU) followed by an infusion of 5 x 10(5) KIU/h until the end of surgery or an equivalent volume of normal saline. Anesthesia and surgical techniques were standardized and systematic deep venous thrombosis prophylaxis was used. Peri- and postoperative blood loss and transfusion were measured. Fibrinolysis, coagulation pathways, and platelet function were assessed. Renal and hepatic function as well as the incidence of deep venous thrombosis also were assessed.

Aprotinin reduced total blood loss from 1,943 +/- 700 ml to 1,446 +/- 514 ml (P < 0.05). This reduction of blood loss occurred during surgery (P < 0.05) and postoperatively (P < 0.001). Total amounts of blood transfused were 3.4 +/- 1.3 units/patient in the control group and 1.8 +/- 1.2 units/patient in the aprotinin group (P < 0.001). The activated partial thromboplastin time was significantly prolonged by aprotinin immediately after surgery, at 50.6 +/- 12.4 versus 32.3 +/- 4.6 s in control patients (P < 0.001), but results of the other coagulation tests were not different between the two groups. No side effects were observed in the aprotinin group. The incidence of deep venous thrombosis in the two groups was not significantly different.

The use of high-dose aprotinin during total hip replacement results in a reduction in both blood loss and the amount of blood transfused. Aprotinin's mode of action, however, remains to be elucidated.