Metabolic vs nutrition support: a hypothesis.

It is now generally accepted that early feeding post injury exerts a positive effect on outcome in the critically ill, despite the fact that many of these patients are well nourished or even overnourished on admission. One possible mechanism is that early feeding post injury may have a positive influence on the duration and intensity of the systemic inflammatory response, especially when coupled with intensive insulin therapy to maintain normoglycemia at <150 mg/dL. Current clinical nutrition guidelines recommend early enteral nutrition providing full nutrition requirements in the critically ill patient; however, in the first week post injury, exclusive enteral feeding is typically inadequate, particularly in protein. A potentially new and different therapeutic goal to modulate the systemic inflammatory response might be more effectively accomplished for the first week post injury by hypocaloric feedings (~9-18 kcal/kg or 50%-75% resting metabolic expenditure) principally as intravenous dextrose but with at least 1 g/kg protein as intravenous amino acids to provide early metabolic support. This proposed regime, along with intensive insulin therapy to maintain glucose homeostasis, should promote the protein synthetic component of the postinjury inflammatory response while reducing net protein catabolism. A formal trial of early metabolic support in the acutely injured should be safe, easy to execute, and potentially efficacious, with subsequent improvement in the inflammatory state and, it is hoped, clinical outcomes.