Dr. Augoustides asks whether antifibrinolytic use confounded our conclusion that even mild hypothermia significantly increases blood loss and transfusion requirement.1Among the studies included in our meta-analysis and as specified in the original publications, antifibrinolytic therapy was used in but one. Specifically, Nathan et al.  2gave a 1-g bolus of tranexamic acid after induction, followed by 2 mg · kg−1· h−1intraoperatively. Because identical doses were used in the normothermic and hypothermic groups, antifibrinolytic use was not a confounding factor.

Similarly, all studies included in our meta-analysis were prospective trials in which thermal management was randomized. Analysis was based on group assignment rather than actual core temperature. Clinical management, whether with regional or general anesthesia, was thus comparable in the randomized groups within each study—again, as specified in the original publications. Induced hypotension was used in only one study, and again, management was comparable in the hypothermic and normothermic groups.3Consequently, anesthetic management was not a confounding factor either.

*The Cleveland Clinic, Cleveland, Ohio. ds@or.org

Rajagopalan S, Mascha E, Na J, Sessler DI: The effects of mild perioperative hypothermia on blood loss and transfusion requirement. Anesthesiology 2008; 108:71–7
Nathan HJ, Parlea L, Dupuis JY, Hendry P, Williams KA, Rubens FD, Wells GA: Safety of deliberate intraoperative and postoperative hypothermia for patients undergoing coronary artery surgery: A randomized trial. J Thorac Cardiovasc Surg 2004; 127:1270–5
Murat I, Berniere J, Constant I: Evaluation of the efficacy of a forced-air warmer (Bair Hugger) during spinal surgery in children. J Clin Anesth 1994; 6:425–9