USE OF FORCED-AIR WARMING DURING AND AFTER OUTPATIENT ARTHROSCOPIC SURGERY

According to a two-phase protocol, 127 patients undergoing arthroscopic knee surgery were randomly assigned to receive intraoperative warming from a forced-air blanket (n = 69) or conventional warmed cotton blankets (n = 58). During the initial phase (Phase I), active warming was applied during the intraoperative period only, permitting double-blind assessment of postoperative events. In Phase II, warming was continued into the recovery area, which unblinded the assessment. Active warming raised skin temperature perioperatively, and reduced the decline in core temperature compared to the control group. Postoperatively, core temperature increased toward preoperative values at similar rates in both treatment groups, but was still lower in control patients after an hour in the postanesthesia care unit (PACU). Postoperative shivering occurred in 35% of all patients and was not prevented by either intraoperative or combined intraoperative and postoperative warming. However, significantly fewer actively warmed patients experienced prolonged postoperative shivering. The addition of postoperative warming appeared to provide little, if any, additional benefit. Despite the decreased duration of postoperative shivering in the actively warmed group, we were unable to demonstrate any reduction in the PACU stay.