Early Versus Late Parenteral Nutrition in Critically Ill Adults
Casaer MP, Mesotten D, Hermans G, et al
N Engl J Med. 2011;365:506-517
Study Summary
Supporting the metabolic needs of critically ill patients is nearly impossible with complete accuracy. Controversy exists about the timing of the initiation of parenteral nutrition in critically ill adults in whom caloric targets cannot be met by enteral nutrition alone. There is particular dissension on this topic between European and North American guidelines.
The authors of a study published in The New England Journal of Medicine sought to compare the effects of late initiation of parenteral nutrition (American and Canadian guidelines) with early initiation (European Society of Parenteral and Enteral Nutrition [ESPEN] guidelines) with respect to mortality and complications in critically ill adults at nutritional risk but not chronically malnourished.
In 2312 patients, parenteral nutrition was initiated within 48 hours after ICU admission (early-initiation group); and in 2328 patients, parenteral nutrition was not initiated before day 8 (late-initiation group). A protocol for the early initiation of enteral nutrition was applied to both groups, and insulin was infused to achieve normoglycemia.
Patients in the late-initiation group were 6.3% more likely to be discharged alive earlier from the ICU and from the hospital. Rates of death in the ICU and in the hospital and rates of survival at 90 days were similar in the 2 groups. Patients in the late-initiation group, as compared with the early-initiation group, had fewer ICU infections (23% vs 26%, P = .008) and a lower incidence of cholestasis. There were 10% fewer patients in the late-initiation group requiring more than 2 days of mechanical ventilation and also a median reduction of 3 days in the duration of renal replacement therapy and lower healthcare costs (all P < .05).
The authors concluded that late initiation of parenteral nutrition results in faster recovery and fewer complications.
Viewpoint
Differences in nutritional guidelines for critically ill patients are difficult to reconcile, particularly with respect to the timing of nutritional support measures.
The ESPEN guidelines recommend initiating parenteral nutrition within 2 days after ICU admission for patients who cannot be adequately fed enterally. The American and Canadian guidelines recommend early initiation of enteral nutrition with delays in initiation of parenteral nutrition through the first week in patients who are not malnourished at baseline. Not surprisingly, there is limited evidence to guide these decisions, reflected in the fact that these clinical practice guidelines are largely based on expert opinion.
This study clearly shows that the early initiation of parenteral nutrition to achieve caloric goals of approximately 25-30 kcal/kg/day results in worse clinical outcomes than delayed initiation of parenteral nutrition for 1 week. However, as with all clinical studies, these data are imperfect: between-group differences in the study's outcomes were small, patients were not seriously malnourished at entry, 60% were cardiac surgical patients, and all received vitamin supplementation and rigorous glycemic control. These data do suggest that for critically ill patients who are not chronically malnourished, delayed initiation of parenteral nutrition will result in fewer complications and may produce superior outcomes. It seems these data should change clinical practice and that all clinical practice guidelines need to be revised.
Abstract