POSTOPERATIVE PROTEIN METABOLISM: EFFECT OF NURSING ELDERLY PATIENTS FOR 24 H AFTER ABDOMINAL SURGERY IN A THERMONEUTRAL ENVIRONMENT

We have studied the effect of intraoperative body heat conservation and 24-h thermoneutrality on postoperative whole body protein turnover using stable isotope methodology in a group of elderly patients undergoing colorectal surgery for rectosigmoid adenocarcinoma. Two groups of eight patients were studied. One group (control, or cold) received routine intraoperative and postoperative care. All patients in the second group (warmed) were maintained at normothermia during anaesthesia and surgery; these patients were nursed after surgery in a warm room (ambient temperature 28–30°C) for a period of 24 h. General anaesthesia, surgical care and nutritional support were similar in both groups. A constant nutritional intake, based on nitrogen 0.1 g kg−1 day−1 and energy 20 kcal kg−1 day−1, was provided orally for 7 days before surgery and i.v. after operation for 4 consecutive days. Whole body protein breakdown and synthesis, as assessed by stable isotope methodology, increased significantly 2 and 4 days after surgery in both groups (P</it><0.01), but the increase in protein breakdown in the warmed group on day 2 was significantly less than that in the cold group (P</it><0.05). The increase in leucine oxidation in the warmed group on the 2nd day after surgery was not significant, and was less than the increase observed in the cold group (P</it><0.05). However, by the 4th day, leucine oxidation was enhanced significantly in both groups (P</it><0.01). The cumulative urinary nitrogen excretion over 4 days and the loss of fat-free mass, as measured by total body potassium 7 days after surgery, were significantly less in the warmed group compared with the cold group (P</it><0.05). Urinary excretion of adrenaline and cortisol after surgery was significantly less in the warmed group compared with the cold group (P</it><0.05). Thus the attenuated whole body protein breakdown and ami no acid oxidation observed in the warmed group after surgery might be explained, to some extent, by the specific hormonal suppression achieved with thermoneutrality.