Energy replacement during parenteral nutrition in surgery, sepsis and cancer

For many years, the increased nutritional requirements of surgical, septic and cancer patients were identified, but no effective therapy existed for averting their negative calorie and nitrogen balance. Parenteral nutrition offered an answer in many of these situations. However, abnormalities in liver function, ventilatory load, hyperglycemia and a disturbed metabolic homeostasis showed that in excessive amounts, glucose can behave as a relatively toxic substance. For cases with increased energy expenditure, new alternatives had to be devised in order to avoid excessive glucose intakes. One obvious possibility in these cases was to refrain from offering more than the basal caloric needs, until the patient had passed the period of acute injury, or other measures had effectively controlled the sepsis or cancer. Other options included the partial substitution of glucose by lipids or amino acids. Preliminary information suggests that this approach could lead to better nutritional outcome and survival rates, but additional studies are required.