Postoperative protein sparing

Abstract

Postoperative nitrogen sparing refers to a therapy that decreases net nitrogen loss from the body following an operation. Protein sparing has long been regarded as a surrogate marker for improved outcome, but a critical review of the evidence indicates that this relation is difficult to establish, especially in the short term. Thus, specific endpoints that evaluate outcome are needed to determine the efficacy of a specific therapy that spares protein. Cost effectiveness must also be considered. A variety of therapies were evaluated using protein-sparing, efficiency, and cost criteria. Evidence was reviewed for glucose, amino acids, parenteral nutrition, enteral nutrition, growth hormone, and glutamine administered during the perioperative period. Only three areas could be identified that spared nitrogen and provided efficacy: (1) preoperative total parenteral nutrition (TPN) for 7 to 10 days before operation in a depleted patient (</=15% body weight loss); (2) the use of growth hormone with nutritional support to promote wound healing (especially in burns) and possibly to enhance muscle strength (particularly in the elderly); and (3) the use of glutamine-supplemented TPN in severely ill surgical patients to decrease mortality. The issue of early tube feeding in trauma patients is still confusing. This therapy must be evaluated by an appropriate study in trauma patients that compares a tube-fed group with an unfed control group. Only by demonstrating improved outcomes and enhanced cost saving with our protein-sparing therapy can we continue to enhance the care of our surgical patients.