Parenteral nutrition in the ICU: Lessons learned over the past few years.

Since the early 1990s enteral nutrition (EN) has been considered the optimal route of feeding rather than parenteral nutrition (PN), which was considered harmful in critically ill patients with intense inflammation. The aim of this review was to summarize recent developments and progress in PN, which have changed the view on this feeding technique. PubMed and personal databases were searched for studies and reviews reporting historical development of PN, and for clinical trials conducted after 2010 investigating PN in critical illness, comparing it to EN or not. Trials from the past decade have explored modalities and timing of artificial feeding. Trials based on equation-estimated energy targets and applying an early full feeding strategy have generally had negative results in terms of complications (infections, prolonged ventilation, and intestinal complications with EN). The few trials that based their targets on measured energy targets have achieved reduction of complications regardless of the route. Opposing enteral and parenteral feeding is no longer rational in the critical care setting. A pragmatic and reasonable approach offers better options for the individual patient. Although PN is simpler to deliver than EN, its metabolic consequences are more complicated to handle. A combination of both techniques may be a more reasonable approach in the sickest patients.