Partial body heating preserves normothermia in patients undergoing orthopaedic surgery.

Objective: This study investigates if warming of the upper or lower half of the body preserves normothermia in patients undergoing major orthopaedic surgery. Additionally, we compared the intraoperative tympanic membrane and urinary bladder temperatures of these patients. Methods: Fifty-four patients undergoing major orthopaedic operations were observed. In all patients general anaesthesia was induced with fentanyl, etomidate, and atracurium and was maintained with isoflurane and nitrous oxide. Thirty patients were randomly allocated to maintain normal body temperatures (WarmTouch 5000(R), Mallinckrodt Medical, level IV, 41-42 degrees C), whereas 24 patients were not actively warmed. Warming of the patients was performed by complete body heating preoperatively and warming of the upper (n = 19) or lower (=11) half of the body intraoperatively. Core temperature was recorded from the tympanic membrane. The urinary bladder temperature was measured by a special urinary catheter. Results: Without active warming of the patients the core temperature decreased 1.6 degrees C during surgery. Core temperature remained constant in all actively heated patients, regardless of upper or lower body heating. Hypothermia of the unwarmed patients was detected by both, tympanic membrane measurement and - with a short delay - the urinary bladder temperature probe. Conclusion: This data suggests that active warming of the upper or lower half of the body during major orthopaedic surgery can preserve normothermia in all patients. During these surgical procedures the urinary bladder temperature was able to represent reliable core temperatures.