Randomized trial of initial trophic versus full-energy enteral nutrition in mechanically ventilated patients with acute respiratory failure

Objective: Enteral nutrition is provided to mechanically ventilated patients who cannot eat normally, yet the amount of support needed is unknown. We conducted this randomized, open-label study to test the hypothesis that initial low-volume (i.e., trophic) enteral nutrition would decrease episodes of gastrointestinal intolerance/complications and improve outcomes as compared to initial full-energy enteral nutrition in patients with acute respiratory failure. Design: Randomized, open-label study. Patients: A total of 200 patients with acute respiratory failure expected to require mechanical ventilation for at least 72 hrs. Interventions: Patients were randomized to receive either initial trophic (10 mL/hr) or full-energy enteral nutrition for the initial 6 days of ventilation. Measurements and Main Results: The primary outcome measure was ventilator-free days to day 28. Baseline characteristics were similar between the 98 patients randomized to trophic and the 102 patients randomized to full-energy nutrition. At enrollment, patients had a mean Acute Physiology and Chronic Health Evaluation II score of 26.9 and a Pao(2)/FIo(2) ratio of 182 and 38% were in shock. Both groups received similar durations of enteral nutrition (5.5 vs. 5.1 days; p = .51). The trophic group received an average of 15.8% +/- 11% of goal calories daily through day 6 compared to 74.8% +/- 38.5% (p < .001) for the full-energy group. Both groups had a median of 23.0 ventilator-free days (p = .90) and a median of 21.0 intensive-care-unit-free days (p = .64). Mortality to hospital discharge was 22.4% for the trophic group vs. 19.6% for the full-energy group (p = .62). In the first 6 days, the trophic group had trends for less diarrhea (19% vs. 24% of feeding days; p = .08) and significantly fewer episodes of elevated gastric residual volumes (2% vs. 8% of feeding days; p < .001). Conclusion: Initial trophic enteral nutrition resulted in clinical outcomes in mechanically ventilated patients with acute respiratory failure similar to those of early full-energy enteral nutrition but with fewer episodes of gastrointestinal intolerance. (Crit Care Med 2011; 39:967-974)