Background and Objectives The goal of the present study was to investigate whether epidural analgesia exerts a protein-sparing effect after colorectal surgery in the presence of hypocaloric glucose supply initiated with surgical skin incision.

Methods We randomly allocated 10 patients to receive general anesthesia combined with epidural anesthesia with bupivacaine, followed by epidural analgesia using bupivacaine/fentanyl, and 10 patients to receive general anesthesia, followed by patient-controlled analgesia with intravenous morphine. All patients received a 48-hour infusion of glucose 10% from surgical skin incision until the second day after surgery. The glucose infusion rate provided 50% of the patient's resting energy expenditure. Kinetics of protein and glucose metabolism were assessed by a stable-isotope tracer technique (L-[1-¹³C]leucine and [6,6-²H₂]glucose).

Results The rate of appearance of leucine increased in the intravenous-analgesia group (112 ± 29 to 130 ± 25 μmol/kg/h) 2 days after surgery, and this increase was more pronounced than in the epidural analgesia group (preoperative 120 ± 24, postoperative 123 ± 22 μmol/kg/h, P < .05). Leucine oxidation rate increased in the intravenous analgesia group from 17 ± 8 to 23 ± 8 μmol/kg/h and in the epidural group from 17 ± 6 to 19 ± 7 μmol/kg/h without the difference between the groups reaching statistical significance (P = .067). Nonoxidative leucine disposal remained unaltered in both groups. No differences in glucose metabolism were seen between the groups.

Conclusions Epidural analgesia inhibits the increase in whole-body protein breakdown in patients receiving perioperative hypocaloric glucose infusion initiated with surgical skin incision. However, oxidative protein loss, protein synthesis, and glucose metabolism are not affected by epidural analgesia.