Effect of amino acid infusion on glucose production in trauma patients

Perioperative amino acid supplementation of hypocaloric glucose does not impair glucose metabolism after surgery

We tested the hypothesis that perioperative amino acid supplementation of hypocaloric dextrose would attenuate the inhibitory effect of glucose on endogenous glucose production after surgery. Sixteen patients undergoing colorectal cancer surgery were randomly assigned to receive intravenous glucose either with or without amino acids. Nutrition was administered over 48 hours from surgical skin incision until the second postoperative day. Glucose provided 50% and amino acids 20% of the patient's measured resting energy expenditure. Glucose rate of appearance was assessed by [6,6-2H2]glucose before and after surgery. Circulating concentrations of glucose, lactate, insulin, and glucagon were also determined. Hypocaloric glucose suppressed postoperative endogenous glucose production to a similar degree in both groups. The circulating concentrations of glucose increased to the same extent, whereas there was no significant change in plasma concentrations of lactate, glucagon, and cortisol. Postoperative plasma levels of insulin were significantly higher in patients receiving amino acids (P = .009). Perioperative amino acid administration does not mitigate the inhibitory effect of glucose on glucose production or aggravate hyperglycemia after colorectal surgery.

Parenteral nutrition and protein sparing after surgery: do we need glucose?

Although capable of inducing an anabolic state after surgery, parenteral nutrition, including glucose, leads to hyperglycemia. Even moderate increases in blood glucose are associated with poor surgical outcome. We examined the hypothesis that amino acids, in the absence of glucose supply, spare protein while preventing hyperglycemia. In this prospective study, 14 patients with colonic cancer were randomly assigned to undergo a 6-hour stable isotope infusion study (3 hours of fasting followed by 3-hour infusions of amino acids, Travasol [Baxter, Montreal, Canada] 10% at 0.02 mL.kg(-1).min(-1), with or without glucose at 4 mg.kg(-1).min(-1)) on the second day after colorectal surgery. Protein breakdown, protein oxidation, protein balance, and glucose production were assessed by stable isotope tracer kinetics using l-[1-(13)C]leucine and [6,6-(2)H2]glucose. Circulating concentrations of glucose, cortisol, insulin, and glucagon were determined. The administration of amino acids increased protein balance from -16+/-4 micromol.kg(-1).h(-1) in the fasted state to 16+/-3 micromol.kg(-1).h(-1). Combined infusion of amino acids and glucose increased protein balance from -17+/-7 to 7+/-5 micromol.kg(-1).h(-1). The increase in protein balance during nutrition was comparable in the 2 groups (P=.07). Combined administration of amino acids and glucose decreased endogenous glucose production (P=.001) and stimulated insulin secretion (P=.001) to a greater extent than the administration of amino acids alone. Hyperglycemia (blood glucose, 10.1+/-1.9 micromol/L) occurred only in the presence of glucose infusion. In summary, excluding glucose from a short-term feeding protocol does not diminish the protein-sparing effect of amino acids and avoids hyperglycemia.

Glutamine-enriched enteral feeding in trauma patients: reduced infectious morbidity is not related to changes in endocrine and metabolic responses

BACKGROUND

Recently we have shown that glutamine-enriched enteral nutrition in trauma patients reduced the occurrence of pneumonia, bacteremia, and sepsis. In that study, no clear explanation for these results was found except for lower tumor necrosis factor (TNF)-soluble receptors, suggesting immunomodulation. Here we present data on the course of endocrine and metabolic plasma mediators that were analyzed to provide more insight into the working mechanism of glutamine.

METHODS

Endocrine and metabolic mediators were measured in plasma samples taken on admission (day 0) and on days 1, 2, 3, 7, and 10. Glucose, prealbumin, albumin, alanine, C-reactive protein, alpha1-antitrypsin, complement factors, cortisol, glucagon, insulin, and growth hormone were assessed by standard techniques.

RESULTS

The rate of feeding, demography, and injury severity did not differ between the glutamine and control group. There was a sustained hyperglycemic response in both groups. Insulin levels rose in the second phase of the period of observation. A moderate cortisol and glucagon response was seen in both groups. There was no alteration in growth hormone levels in either group. C-reactive protein, alpha1-antitrypsin, and complement factors showed similar increases in both groups but levels remained in the normal range. The course of alanine, albumin, and prealbumin also showed no difference between the groups.

CONCLUSIONS

Glutamine-enriched enteral nutrition had no influence on the endocrine and metabolic response in trauma patients. Therefore, the reduction in infectious morbidity seen in glutamine-supplemented trauma patients is most likely not explained by a modulation of the humoral stress response and its metabolic consequences.

Abnormalities in glucose metabolism and their relevance to nutrition support in the critically ill

This review covers the recent advances that have been made in understanding the abnormalities of glucose metabolism found in critically ill patients. The alterations in the pathways of glucose production and utilization and the hormones and cytokines responsible for these are described. Therapies that have the potential to alter abnormal glucose metabolism and improve nutritional status are discussed.