The effect of three different doses of tranexamic acid on blood loss after cardiac surgery with mild systemic hypothermia (32°C)

Objective: Prophylactic administration of tranexamic acid (TA),an antifibrinolytic agent, decreases bleeding after cardiac surgery with systemic hypothermia (25 degrees C to 29 degrees C). Warmer systemic temperatures during cardiopulmonary bypass (CPB) may reduce bleeding and thus alter the requirement for TA. The effect of three different doses of TA an bleeding after cardiac surgery with mild systemic hypothermia (32 degrees C) is evaluated. Design: Double-blind, prospective, randomized study. Setting: University hospital. Participants: One hundred fifty adult patients undergoing aortocoronary bypass or valvular cardiac surgery. Interventions:Patients received TA, 50 (n = 50), 100 (n = 50), or 150 (n = 50) mg/kg intravenously before CPB with mild systemic hypothermia. Measurements and Main Results: Blood loss through chest drains over 6, 12, and 24 hours after surgery and total hemoglobin loss were measured. Autotransfused blood, transfused banked blood and blood products, and coagulation profiles were measured. Analysis of variance on lag-transformed data far blood loss and confidence intervals (Cls) of 0.95 were calculated and transformed to milliliters of blood. No patient was re-explored for bleeding. Blood loss at 6 hours was statistically greater in the 50-mg/kg group compared with the other two groups (p = 0.03; p = 0.02). Total hemoglobin loss was statistically greater in the 50-mg/kg group compared with the 150-mg/kg group (p = 0.04). There was no statistical difference in blood transfusion rate or coagulation profiles among the three groups. However, preoperative hemoglobin revel was statistically lower in the 150-mg/kg group compared with the other two groups (p = 0.01). Conclusion: Of the three doses of TA studied, the most efficacious and cost-effective dose to reduce bleeding after cardiac surgery with mild hypothermic systemic perfusion is 100 mg/kg. Copyright (C) 1998 by W.B. Saunders Company.