Intraoperative protein sparing with glucose

Abstract

We examined the hypothesis that glucose infusion inhibits amino acid oxidation during colorectal surgery. We randomly allocated 14 patients to receive intravenous glucose at 2 mg·kg−1·min−1 (glucose group) starting with the surgical incision or an equivalent amount of normal saline 0.9% (control group). The primary endpoint was whole body leucine oxidation; secondary endpoints were leucine rate of appearance and nonoxidative leucine disposal as determined by a stable isotope tracer technique (l-[1-13C]leucine). Circulating concentrations of glucose, lactate, insulin, glucagon, and cortisol were measured before and after 2 h of surgery. Leucine rate of appearance, an estimate of protein breakdown, and nonoxidative leucine disposal, an estimate of protein synthesis, decreased in both groups during surgery ( P < 0.05). Leucine oxidation intraoperatively decreased from 13 ± 3 to 4 ± 3 μmol·kg−1·h−1 in the glucose group ( P < 0.05 vs. control group) whereas it remained unchanged in the control group. Hyperglycemia during surgery was more pronounced in patients receiving glucose (9.7 ± 0.5 mmol/l, P < 0.05 vs. control group) than in patients receiving normal saline (7.1 ± 1.0 mmol/l). The administration of glucose caused an increase in the circulating concentration of insulin ( P < 0.05) resulting in a lower glucagon/insulin quotient than in the control group ( P < 0.05). Intraoperative plasma cortisol concentrations increased in both groups ( P < 0.05), whereas plasma concentrations of lactate and glucagon did not change. The provision of small amounts of glucose was associated with a decrease in amino acid oxidation during colorectal surgery.