When and how should I feed the critically ill patient?

The principal purpose of critical care nutrition is to arrest the loss of lean body mass and to maintain and restore energy-dependent homeostatic functions. There is no well-validated tool that evaluates the nutritional status of the critically ill patient, so opinion-based clinical evaluation of nutritional status is preferred. There is no evidence that parenteral nutrition (PN) is superior to enteral nutrition (EN) during the first 7 days of critical illness and vice versa. Moreover, early EN and early PN feeding do not appear to improve outcomes compared with delayed or hypocaloric nutrition. Parenteral nutrition should probably be delayed for up to 7 days for well-nourished patients. Adding PN to EN early in critical illness to achieve energy goals does not improve outcomes. The status of PN in malnourished or undernourished patients is unclear. PN is not associated with elevated infection risk. EN is associated with gastrointestinal complications, principally vomiting, probably clinically insignificant. EN is safe to administer to patients receiving vasoactive drugs after the initial shock period. For the majority of patients, gastric feeding should be attempted, and this usually results in achieving nutritional goals. It is probably unnecessary to routinely check gastric residual volumes. EN is superior to PN in patients with acute pancreatitis. In conclusion, there is currently no evidence that administration of a patient’s full estimated energy requirements improves outcomes in early critical illness. Consequently, trophic or hypocaloric feeding is a reasonable approach in the first 7 days.