Epidural blockade improves substrate utilization after surgery

The purpose of this study was to test the hypothesis that epidural blockade with local anesthetic improves the anticatabolic effects of glucose after colorectal surgery. Sixteen patients were randomly assigned to undergo a 6-h stable isotope infusion study (3 h fasted, 3 h glucose infusion at 4 mg.kg(-1).min(-1)) on the second postoperative day with or without perioperative epidural blockade. Protein synthesis, breakdown and oxidation, and glucose production and clearance were assessed by L-[ 1-C-13] leucine and [6,6-H-2(2)]glucose. Epidural blockade did not affect protein and glucose metabolism in the fasted state. Glucose infusion increased glucose clearance (P< 0.05), accompanied by an increase in the respiratory quotient (P< 0.05) and a decrease in leucine oxidation (P< 0.05) only in the presence of epidural blockade. An inverse correlation (r = -0.74, P< 0.05) between changes in glucose clearance and leucine oxidation was observed. In conclusion, epidural blockade facilitates whole body glucose uptake and inhibits endogenous protein oxidation after abdominal surgery, indicating a shift from a protein to a more glucose-dominated substrate utilization.