Warming by resistive heating maintains perioperative normothermia as well as forced air heating

Background. Even mild perioperative hypothermia is associated with several severe adverse effects. Resistive heating has possible advantages compared with other active warming systems because it can heat several fields independently. To assess this new warming system, we measured core temperature in patients during surgery who were warmed with circulating water mattresses, forced air covers or resistive heating covers. Methods. Twenty-four patients undergoing laparoscopic cholecystectomy were randomly assigned to (i) circulating water mattress (38degreesC), (ii) forced air warming (set to 'medium') or (iii) carbon-fibre resistive warming (38degreesC). Warming was applied throughout anaesthesia and surgery. The groups were compared using one-way ANOVA and Student-Newman-Keuls tests. Results. Confounding factors were similar among the groups. Core temperatures in each group decreased for 20 min, but subsequently increased in the forced air and resistive heating groups. There was no significant difference between the forced air and resistive heating groups at any time. In contrast, core temperature in the circulating water group continued to decrease. Consequently, core temperature in the circulating water group was significantly lower than in the other groups 30 min after anaesthetic induction and at later times. Conclusions. Resistive heating maintains core body temperature as well as forced air heating and both are better than circulating water. Resistive heating offers the advantage of adjustable heating pods.