Resistive-heating and forced-air warming are comparably effective

Serious adverse outcomes from perioperative hypothermia are well documented. Consequently, intraoperative warming has become routine. We thus evaluated the efficacy of a novel, nondisposable carbon-fiber resistive-heating system. Twenty-four patients undergoing open abdominal surgery lasting approximately 4 h were randomly assigned to warming with 1) a full-length circulating water mattress set at 42degreesC, 2) a lower-body forced-air cover with the blower set on high, or 3) a three-extremity carbon-fiber resistive-heating blanket set to 42degreesC. Patients were anesthetized with a combination of continuous epidural and general anesthesia. All fluids were warmed to 37degreesC, and ambient temperature was kept near 22degreesC. Core (tympanic membrane) temperature changes among the groups were compared by using factorial analysis of variance and Scheffe F tests; results are presented as means +/- SD. Potential confounding factors did not differ significantly among the groups. In the first 2 h of surgery, core temperature decreased by 1.9degreesC +/- 0.5degreesC in the circulating-water group, 1.0degreesC +/- 0.6degreesC in the forced-air group, and 0.8degreesC +/- 0.2degreesC in the resistive-heating group. At the end of surgery, the decreases were 2.0degreesC +/- 0.8degreesC in the circulating-water group, 0.6degreesC +/- 1.0degreesC in the forced-air group, and 0.5degreesC +/- 0.4degreesC in the resistive-heating group. Core temperature decreases were significantly greater in the circulating-water group at all times after 150 elapsed minutes; however, temperature changes in the forced-air and resistive-heating groups never differed significantly. Even during major abdominal surgery, resistive heating maintains core temperature as effectively as forced air.