The impact of mild peri-operative hypothermia on the effectiveness of tranexamic acid in total hip arthroplasty

Purpose Surgical patients experience inadvertent hypothermia as a result of anaesthesia-induced thermoregulatory impairment. Previous studies have found that hypothermia is associated with increased blood loss and transfusion requirements. This study examined the incidence of hypothermia in patients undergoing total hip arthroplasty (THA), whether hypothermia is associated with increased blood loss, and whether any such association is modified by tranexamic acid (TXA) administration. Methods An observational prospective study was performed in 941 consecutive patients undergoing elective THA, with and without intra-operative administration of TXA. The presence of hypothermia on post-anaesthesia care unit admission was determined, and the post-operative bleeding index calculated. Transfusions and complications were documented. Results The incidence of peri-operative inadvertent hypothermia was 84.2 %. TXA was administered to 751 (79.8 %) patients. The bleeding index was 2.6 (95 % confidence interval [CI] 2.6–2.7) in patients treated with TXA and 3.1 (95 % CI 2.8–3.4) in patients who did not receive TXA ( p = 0.012). Mild hypothermia did not have a significant impact on the bleeding index (difference, −0.4; 95 % CI, −1.1 to +0.2; p = 0.190), nor on the effectiveness of TXA (difference, 0.4; 95 % CI, −0.3 to +1.1; p = 0.250). Conclusion The incidence of hypothermia in our THA population was high, despite peri-operative air warming. However, mild hypothermia was not significantly associated with increased blood loss and did not reduce the effectiveness of TXA.