Optimal timing for the initiation of enteral and parenteral nutrition in critical medical and surgical conditions.

The early provision of nutrients as part of specialized therapy for critically ill patients admitted for critical medical and surgical conditions is recommended by various international guidelines. Enteral nutrition is the first option and should be initiated 24-48 h after admission to an intensive care unit. Even after gastrointestinal anastomosis, early oral or enteral feeding is not only safe but also associated with enhanced recovery and fewer complications. Recent studies showed that the use of an enteral diet or parenteral nutrition that contains immune nutrients enhances the recovery of critically ill patients. Although the precise caloric target remains controversial, the general consensus advocates the avoidance of prolonged hypocaloric or hypercaloric feeding. However, there is still debate about the timing of the initiation of parenteral nutrition when enteral nutrition either is impossible or does not meet the nutritional goals. Although controversy remains, two recent studies showed that when enteral feeding is not feasible the early initiation of parenteral nutrition was not associated with palpable benefit.