Infusion Therapy, Parenteral Nutrition and Metabolic Complications in the Postoperative PeriodSummary. The postoperative period is characterized by a typical imbalance of hormonal activities and of the intermediary metabolism. The extent of this reaction depends on the nature of the surgical intervention, but it is modified by other factors, e. g., pre-existing disease or nutritional state. An adequate infusion therapy is helpful in avoiding heaw metabolic complications, which can be induced by the disequilibrium syndrome.