Given that malnutrition in critically ill patients is associated with poor outcomes, artificial nutrition, preferably enteral nutrition, is often provided, particularly to mechanically ventilated patients with acute lung injury (ALI).1-2 The importance of enteral nutrition in this population is thought to be related to maintaining gut integrity, modulating both stress and the systemic immune response, and attenuating gut integrity. However, despite the fact that the benefits of enteral nutrition are well documented in the literature, there is a paucity of data regarding the timing, formulation, and amount of enteral nutrition that needs to be provided to this population.
In a study published in JAMA by Rice and colleagues, the authors investigated whether there is an advantage to restricting the amount of initial enteral intake among mechanically ventilated patients with ALI. The EDEN (Early vs. Delayed Enteral Nutrition in ALI) study was a large, un-blinded trial of 44 sites that recruited 1000 mechanically ventilated patients with ALI. The authors hypothesized that the administration of a reduced, trophic feeding which is about 25% of target full feeding target during the first 6 days would increase ventilator-free days compared with a more actively advanced conventional full feeding regimen. The full-feeding group (492 patients) received enteral nutrition that was advanced to goal as rapidly as possible (25-30 kcal/day of non-protein calories and 1.2-1.6 g/kg per day of protein) and the trophic group (508 patients) received 10-20kcal/hour. A protocol specified holding parameters for high gastric residual volume (>400ml).3
The authors noted that restricting the amount of feeding neither reduces the duration of mechanical ventilation (the trophic group averaged 14.9 days, the full group averaged 15 days, P=0.89) nor improves mortality relative to full enteral feeding (23.2 vs. 22.2%, P=0.77), but the trophic nutritional strategy was associated with less gastrointestinal intolerance [the full-feeding group experienced more vomiting (2.2% vs. 1.7% of patient feeding days; P=0.05), elevated gastric residual volumes (4.9% vs. 2.2% of feeding days; P <0.001), and constipation (3.1% vs. 2.1% of feeding days; P=0.003)]
The limitations of this study included the fact that there might be some reporting bias due to the study being un-blinded and the fact that most patient were treated in medical intensive care units. Also, malnourished or underweight patients were excluded from the study.
1. McClave SA, Martindale RG, Vanek VW, et al. A.S.P.E.N. Board of Directors; American College of Critical Care Medicine; Society of Critical Care Medicine. Guidelines for the provision and assessment of nutrition support therapy in the adult critically ill patient. JPEN J Parenter Enteral Nutr
Heyland DK, Dhaliwal R, Drover JW, et al. Canadian Critical Care Clinical Practice Guidelines Committee. Canadian Clinical Practice Guidelines for nutrition support in mechanically ventilated, critically ill adult patients. JPEN J Parenter Enteral Nutr
3. National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network. Initial trophic vs full enteral feeding in patients with acute lung injury: the EDEN randomized trial. [published ...