Nutritional and metabolic consequences of thermal injury.

Major burns produce a variety of metabolic and nutritional consequences. The patient's metabolic rate is often doubled, and caloric demands of 3000 to 5000 calories per day are not uncommon. There are marked hormonal changes characterized by an increase in secretion of catecholamine and glucagon and a reversal of the normal insulin-to-glucagon ratio. Serum glucose increases primarily through hepatic gluconeogenesis to meet the increased demands of the burn wound and of the increased metabolic rate. Lipids may be available but they are an inefficient source of calories. Skeletal and visceral proteins are mobilized to meet the increased nutritional demands. The overall result is a severely catabolic patient in negative nitrogen balance, with decreased immunologic function and all of the wound-healing problems associated with protein and calorie malnutrition. Aggressive nutritional support (using enteral feeding whenever possible) is essential. Supplemental feedings should be started on all patients unable to reach their recommended calorie and protein requirements through regular oral diet. An increase in protein intake (calorie-to-nitrogen ratio of 100:1) may be beneficial. By establishing nutritional goals and monitoring daily weight, calorie count, protein intake, and biochemical parameters, the physician can significantly improve the chances of survival of even the most seriously injured patients.