[When a surgical patient needs parenteral nutrition].

Introduction: Some recent studies suggest that the blanket use of parenteral nutrition may be harmful in the event of short-term starvation due to acute illness. Utilization of endogenous substrate resources which are mobilized anyway due to acute illness or operation allows the organism to survive and recover from acute damage without nutritional support. Modern, less invasive procedures in surgery, good preoperative nutritional status and early recovery of food intake after surgery on the one hand and the side effects and risks of artificial nutrition on the other hand raise the question whether surgery in general still needs parenteral nutrition. Even on the basis of modern knowledge we cannot explain why, in standard administration of parenteral nutrition, there is a higher incidence of postoperative complications. Is parenteral nutrition directly toxic or useless, or are we just unable to avoid the side effects of improper application?

Methods: In most cases, the body has protein and energy storage large enough to heal the wound and anastomosis. But the hypometabolic status of the starved organism requires more time for the healing process, and ubiquitous protein catabolism due to postoperative inflammation can exhaust the immune defences of the body. The importance of nutritional support and metabolic optimization is shifting to preoperative strengthening. Artificial feeding is used to stimulate protein synthesis which is necessary for healing on the one hand, and to replenish protein and energy reserves on the other. Protracted catabolism is a risk factor for prolonged immunosuppression and fatal loss of endogenous protein.

Conclusion: Malnutrition is a significant cause of postoperative complications. In planned operations, artificial nutritional support is targeted at patients with low protein synthesis (persons with low food intake lasting several days), patients who are obviously malnourished, those with expected long starvation (5-7 days), and patients with high catabolism. Protein synthesis accelerates in a few days after nutritional support has been started. The nutritional indicators improve in a few weeks after nutrition has been initiated and the risk of postoperative complications due to malnutrition persists up to several months after surgery.