Effect of halothane, enflurane and isoflurane on body temperature during and after surgery

The superficial and deep body temperatures of 40 healthy females undergoing total abdominal hysterectomy were measured during surgery and for 4 h afterwards. The patients were allocated randomly to one of five groups and anaesthetized to produce an end-tidal concentration of 1% halothane, 1% enflurane, 2% enflurane, 1% isoflurane or 2% isoflurane. The patients received also 70% nitrous oxide in oxygen and neuromuscular blockade. The theatre temperature was maintained at 22.0 degrees C. There were significant body temperature changes during operation in all groups. The mean (SD) decrease in core temperature over 85 min was approximately 1.1 (0.3) degrees C in the 1% halothane, 2% enflurane and 2% isoflurane groups, and 0.6 (0.4) degrees C in the 1% enflurane and 1% isoflurane groups (P less than 0.05). During the recovery period the 1% halothane, 2% enflurane and 2% isoflurane groups took 2 h to rewarm to preoperative temperatures, and the rate of rewarming during this time was similar for all groups.