Effect of laparoscopic colon resection on postoperative glucose utilization and protein sparing - An integrated analysis of glucose and protein metabolism during the fasted and fed states using stable isotopes

Hypothesis: Using a stable isotope method to quantify postoperative changes in glucose and protein metabolism, patients undergoing laparoscopic-assisted colon resection and receiving 4 mg(.)kg(-1.)min(-)1 of dextrose intravenously will (1) have more pronounced suppression of endogenous glucose production, leading to (2) a greater reduction in whole-body protein breakdown. Design: Randomized protocol study. Setting: Tertiary health care center in Montreal, Quebec. Patients: Twelve patients scheduled for colonic resection were randomly allocated to undergo either laparoscopic (n = 6) or open (n = 6) surgery. Interventions: Patients underwent a 6-hour stable isotope infusion study (3 hours fasted and 3 hours fed with dextrose infusion) on postoperative day 2. Whole-body protein breakdown and synthesis, amino acid oxidation, and endogenous glucose production and clearance were measured during the postabsorptive state using L-[1-C-13]leucine and [6,6-H-2(2)] glucose. Gas exchange and plasma concentrations of metabolites and hormones were also measured. Main Outcome Measures: Endogenous glucose production and whole-body protein breakdown during the fasted and fed states. Results: In the fasted state, laparoscopy did not affect protein and glucose metabolism. Dextrose infusion suppressed endogenous glucose production in both groups, with the greatest extent in the laparoscopic group (P = .01). Higher respiratory quotients (P = .001) in the latter group also indicated increased exogenous glucose oxidation. Neither surgical approach nor nutrition affected aspects of protein metabolism. Conclusions: Laparoscopy for colon resection facilitates whole-body glucose uptake and utilization and oxidation of exogenous glucose with no protein-sparing effect. The laparoscopic approach modulates gluconeogenesis, although it is not sufficient in the presence of exogenous energy to promote nitrogen retention.