Effect of heat conservation during and after major abdominal surgery on muscle protein breakdown in elderly patients.

Changes in mean body temperature and muscle protein metabolism were studied in elderly patients undergoing large bowel surgery. Two groups were studied: in one, efforts were made to maintain the patients normothermic during and after surgery by warming the fresh gases, the i.v. fluids, by placing warmed cotton padding around the exposed parts of the body and by covering the patients with a metallized plastic sheet in the recovery period. The other group received routine management. Otherwise the anaesthetic technique was comparable. The excretion of the amino acid 3-methylhistidine (3-MeH), an indicator of muscle protein breakdown, and urea nitrogen loss were measured in the urine collected the day before, and on the 2nd and 4th postoperative days. Prevention of heat loss during and after surgery caused a significant decrease in muscle protein degradation and nitrogen loss.