Malnutrition in cardiac and critical illness is associated with a compromised clinical outcome. The aim of nutrition therapy is to prevent these complications and particularly to attenuate lean tissue wasting and the loss of muscle force and of physical function. During the last decade, several well-powered randomized controlled nutrition trials have been performed. Their results challenge the existing nutrition practices in critically ill patients. Enhancing the nutritional intake and the administration of specialized formulations failed to evoke clinical benefit. Some interventions even provoked an increased mortality or a delayed recovery. These unexpected new findings might be, in part, caused by an important leap forward in the methodological quality in the recent trials. Perhaps reversing early catabolism in the critically ill patient by nutrition or anabolic interventions is impossible or even inappropriate. Nutrients effectively suppress the catabolic intracellular autophagy pathway. But autophagy is crucial for cellular integrity and function during metabolic stress, and consequently its inhibition early in critical illness might be deleterious. Evidence from large nutrition trials, particularly in acute cardiac illness, is scarce. Nutrition therapy is therefore focused on avoiding iatrogenic harm. Some enteral nutrition is administered if possible and eventually temporary hypocaloric feeding is tolerated. Above all, the refeeding syndrome and other nutrition-related complications should be prevented. There is no indication for early parenteral nutrition, increased protein doses, specific amino acids, or modified lipids in critical illness.
Optimal timing, dose and route of early nutrition therapy in critical illness and shock: the quest for the Holy Grail
