Timing and Indication for Parenteral Nutrition in the Critically Ill

Abstract

The paradigm of improved vital and functional outcome by optimized artificial feeding early in critical illness has been recently challenged by several large RCT's. Artficial feeding is unable to attenuate muscle catabolism. At higher doses and particularly when given intravenously early feeding even induces morbidity. In this chapter we will review the history of feeding, the observational data supporting early enhanced feeding and the evidence from RCT's pleading against it. Finally we will discuss the mechanisms -particularly inhibition of autophagy- that may explain the failure of early (parenteral) nutrition in the critically ill.