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We have measured aural canal (core) and skin temperatures, and body heat content in 45 patients undergoing elective hip arthroplasty. They received general anaesthesia which included thiopentone, vecuronium and enflurane and nitrous oxide in oxygen. Patients were allocated randomly to three groups: group 1, control (n = 15), received no intraoperative warming device; group 2 had passive skin surface warming (metallized plastic sheet, Thermolite (n = 15); and group 3 had active skin surface warming (forced heated air, Bair-Hugger) (n = 15). Duration of surgery, fluid administration and the temperature and relative humidity of the operating theatre were similar for the three groups. Core temperature and mean body heat content decreased significantly during surgery in groups 1 and 2 (aural canal temperature 1.5 and 1.0 degrees C, and mean body heat content 287 and 189 kJ, respectively), while in group 3 these variables remained near preoperative values (P = 0.001). Mean skin and hand temperatures decreased in the control group, increased in the active warming group and were unchanged in the passive warming group (P < 0.005), indicating that the forced heated air system was very efficient in providing thermal homeostasis during surgery, while the metallized plastic sheet was able to insulate the skin only from radiant and convective heat losses, without attenuating the reduction in core temperature.

1. The present study was designed in an attempt to resolve conflicting views currently in the literature relating to the effect of surgery on various aspects of protein metabolism. 2. Sequential post-operative (2, 4 and 6 days) changes in whole-body protein turnover, forearm arteriovenous difference of plasma amino acids, glucose, lactate and free fatty acids, muscle concentration of free amino acids, RNA and protein, urinary nitrogen and 3-methylhistidine, plasma concentrations of insulin, cortisol and growth hormone, and resting metabolic rate, were measured in six patients undergoing uncomplicated elective total abdominal hysterectomy. 3. All patients received a constant daily diet, either orally or intravenously, based on 0.1 g of nitrogen/kg and an energy content of 1.1 times the resting metabolic rate for 7 days before and 6 days after surgery. 4. Whole-body protein turnover, synthesis and breakdown increased significantly 2 days after surgery (P less than 0.05) and returned towards pre-operative levels thereafter. 5. Forearm release of branched-chain amino acids and alanine, and efflux of glucose and lactate, were enhanced 4 days after surgery (P less than 0.05). Muscle glutamine and alanine concentrations were decreased on the fourth and sixth days after surgery (P less than 0.05). The RNA/protein ratio (indicating the capacity for protein synthesis) was unaltered. 6. A significant increase in urinary nitrogen and 3-methylhistidine was observed on days 3 and 4 after surgery (P less than 0.05). Thereafter, these parameters remained elevated, although failing to reach statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)

To determine if general anaesthesia alone or in conjunction with surgery alters body protein turnover, we studied six healthy, unpremedicated females undergoing elective total abdominal hysterectomy. Changes in protein metabolism, synthesis and breakdown were estimated by an isotope dilution technique using a continuous infusion of the stable isotope tracer, L-[1-13C]leucine, before anaesthesia (4 h), during anaesthesia alone (1 h), during anaesthesia and surgery (1 h) and in the recovery period (2 h). General anaesthesia comprised thiopentone, pancuronium, enflurane (1 MAC) and oxygen-enriched air. An isotopic steady state in plasma 13C-alpha-ketoisocaproate (13C alpha-KIC) and expired 13C-carbon dioxide were obtained during the four periods. Collections of plasma and expired air were made during the steady state periods and plasma alpha-KIC enrichment measured to indicate precursor pool labelling from which leucine flux (equal to protein breakdown in the post-absorptive state) and oxidation were calculated, and whole body protein synthesis was derived. Whole body protein breakdown did not change with anaesthesia, but decreased with both surgery and during the acute recovery period (P less than 0.05). Protein synthesis did not change with anaesthesia and surgery, but decreased significantly after surgery (P less than 0.05).

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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.

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