Aggressive warming reduces blood loss during hip arthroplasty

We evaluated the effects of aggressive warming and maintenance of normother mia on surgical blood loss and allogeneic transfusion requirement. We rando mly assigned 150 patients undergoing total hip arthroplasty with spinal ane sthesia to aggressive warming (to maintain a tympanic membrane temperature of 36.5 degrees C) or conventional warming (36 degrees C). Autologous and a llogeneic blood were given to maintain a priori designated hematocrits. Blo od loss was determined by a blinded investigator based on sponge weight and scavenged cells. postoperative loss was determined from drain output. Resu lts were analyzed on an intention-to-treat basis. Average intraoperative co re temperatures were wanner in the patients assigned to aggressive warming (36.5 degrees +/- 0.3 degrees vs 36.1 degrees +/- 0.3 degrees C, P < 0.001) . Mean arterial pressure was similar in each group preoperatively, but was greater intraoperatively in the conventionally warmed patients: 86 +/- 12 v s 80 +/- 9 mm Hg, P < 0.001. Intraoperative blood loss was significantly gr eater in the conventional warming (618 mL; interquartile range, 480-864 mL) than the aggressive warming group (488 mL; interquartile range, 368 -721 m L; P = 0.002), whereas postoperative blood loss did not differ in the two g roups. Total brood loss during surgery and over the first two postoperative days was also significantly greater in the conventional warming group (167 8 mL; interquartile range, 1366 -1965 mL) than in the aggressively warmed g roup (1,531 mL; interquartile range, 1055-1746 mL, P = 0.031). A total of 4 0 conventionally warmed patients required 86 units of allogeneic red blood cells, whereas 29 aggressively warmed patients required 62 units (P = 0.051 and 0.061, respectively). We conclude that aggressive intraoperative warmi ng reduces blood loss during hip arthroplasty.