In the News
Current guidelines on the use of enteral nutrition in critically ill patients recommend that those patients who are expected to spend longer than two days in the ICU begin enteral nutrition within 48 hours of admission to the unit, when feasible (within 24 hours is preferred), yet 40% to 60% of critically ill patients don't receive enteral nutrition within that time period. Wondering whether the low rate of compliance with published guidelines was the result of clinical experience refuting the recommendation, researchers conducted a systematic review of the literature and discovered that the recommended practice does, in fact, have teeth: enteral nutrition provided to critically ill patients within 24 hours of admission to the ICU may significantly reduce a patient's risk of dying—or developing pneumonia or multiple organ dysfunction syndrome.
The researchers evaluated 505 randomized, controlled trial reports on early enteral nutrition. Of the 30 that addressed the timing of nutrition administration, only six were methodologically sound enough (or conformed enough with the factors being analyzed) to be included. The six trials reviewed involved a total of 234 patients. Standard treatment (control) options in the studies included enteral nutrition beginning later than 24 hours after injury or ICU admission.
Precisely how soon after fluid resuscitation is completed and the patient is hemodynamically stable enteral feeding should be started is debated. According to guidelines published by the Society of Critical Care Medicine and the American Society for Parenteral and Enteral Nutrition, there's a "window of opportunity," from "within 24 to 72 hours" after admission or the "onset of a hypermetabolic insult," when feedings are "associated with less gut permeability."
When asked in an e-mail about this longer "window," the report's lead author, Gordon S. Doig, associate professor of intensive care medicine at Northern Clinical School, University of Sydney, New South Wales, Australia, pointed out that current Australian guidelines, which he and his colleagues published in JAMA in 2008, recommend commencing within 24 hours, as do European and Canadian guidelines, and the results of the current metaanalysis appear to support beginning enteral nutrition within 24 hours.
"We believe that the evidence supporting early nutrition is better than the evidence for many other things we do," Doig wrote to AJN. "We have a convincing metaanalysis to support early [parenteral nutrition] and now early [enteral nutrition]. Evidence from metaanalyses may not convince all people, however." The report calls for "improvements in the conduct and reporting of future trials" concerning the timing of enteral and parental nutrition in critically ill patients, and to that end, Doig wrote, as of October 2009 he had already enrolled 880 of a planned 1,470 patients into a randomized, controlled trial of early parenteral nutrition.
The review recommends that health professionals use "judicious clinical judgment" in applying these findings, which may be unsuitable for some patients. Doig also pointed out that the current Australian guidelines list contraindications to enteral nutrition, including bowel obstruction, acute pancreatitis, and imminent bowel resection or endoscopy. In such cases, the guidelines recommend early parenteral nutrition instead.
In the recent metaanalysis, only one of the six trials addressed rates of vomiting, but no difference between groups was found. None of the reports addressed aspiration.
1. Doig GS, et al. Intensive Care Med 2009 Sep 24. [Epub ahead of print]; McClave SA, et al. JPEN J Parenter Enteral Nutr 2009; 33(3);277–316.