Since the first randomized trials comparing TPN to the then standard of care which was intravenous normal saline infusion, much progress in nutritional support has been made. In addition, a deeper understanding of the physiologic derangements in surgical nutritionally deficient patients allows the current clinical practitioners to identify patients preoperatively at risk for nutritionally related complications. Improvements in techniques and equipments as well as formulations have made parenteral nutrition safer and effective. The enteral route however, continues to be the optimal approach to aggressive supplemental nutrition in those patients capable of this mode of administration.
The current recommendation by the ESPN is to employ EN in all patients without contraindications who require nutritional support. The surgical patient with established malnutrition should begin aggressive nutrition at least 7–10 days prior to surgery. Those patients in whom eating is not anticipated beyond the first five days following surgery should receive the benefits of early enteral or parenteral feeding depending on whether the gut can be used. Many patients may benefit from newer enteral formulations, such as those designed to enhance immune function (Immunonutrition), as well as other disease-specific formulations, such as pulmonary insufficiency and renal dysfunction.