Nitrogen-sparing effect of epidural administration of local anesthetics in colon surgery.

A nitrogen-sparing effect of epidural anesthesia has been clearly demonstrated in gynecological and lower abdominal surgery. To determine if epidural anesthesia also has a protein-sparing effect during major upper or mid-abdominal surgery, postoperative nitrogen balance and 3-methylhistidine urinary excretion (an index of skeletal muscle protein catabolism) were measured for 6 days in 28 patients who had undergone colon resection for cancer with general anesthesia (N2O-O2-1% enflurane) either supplemented with low dose fentanyl plus intermittent systemic pentazocine for postoperative pain (n = 13), or the same general anesthetic plus epidural injection of either etidocaine 1% intraoperatively and bupivacaine 0.25% postoperatively (n = 8) or meperidine (n = 7) for 48 hr after skin incision. The cumulative 6-day nitrogen balance and the cumulative 3-methylhistidine urinary excretion were significantly less after epidural injection of etidocaine intraoperatively and bupivacaine postoperatively than in the two other groups. There was a significant correlation between the daily urinary excretion of 3-methylhistidine and the daily nitrogen balance in the three groups. This study suggests that in colon surgery, epidural analgesia with local anesthetics in the postoperative period improves nitrogen balance and this effect takes place partly in the muscle.