Intraoperative hypothermia and blood loss: are antifibrinolytic exposure and variations in anesthetic technique possible confounders?

To the Editor:—I read with great interest the excellent article by Dr. Rajagopalan et al. detailing their meta-analysis to investigate the relation between mild perioperative hypothermia, blood loss, and transfusion. Their analysis demonstrated that mild hypothermia increases blood loss by approximately 16% and increases the risk for transfusion by approximately 22%. My first question to the authors is whether perioperative antifibrinolytic exposure has confounded the results of the meta-analysis. For example, tranexamic acid was used in the one cardiac study that did not show increased blood loss or transfusion due to hypothermia. Was antifibrinolytic therapy a major confounder across studies included in the meta-analysis? Does antifibrinolytic exposure explain the studies that documented no increased bleeding or transfusion risk due to mild hypothermia? My second question to the authors is whether these negative studies are confounded by hemostatic variations in anesthetic technique, such as induced hypotension and/or regional anesthesia. I congratulate Dr. Rajagopalan et al. on their excellent article that has further highlighted the importance of perioperative euthermia. I look forward to their comments. John G. T. Augoustides, M.D., F.A.S.E., Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania. [email protected]