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

Abstract

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 PaO2/FiO2 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.

Trial registration: ClinicalTrials.gov NCT00252616.

Figure 1. Full-energy Feeding Protocol

The instructions in the boxes on the right are intended to advance enteral nutrition rapidly while the boxes on the left are to ensure feeds are advanced safely.

Figure 2. Patient Screening, Enrollment, and Follow-up

Figure 3. Calories of Enteral Nutrition Received per Day in Patients Receiving Enteral Feeds

Daily calories for patients receiving trophic vs. full-energy enteral nutrition for study days 0-12. * P<0.001; † P=0.001

Figure 4. Distribution of VFD to Study Day 28 by Treatment

The black line represents the median, the shaded box the IQR and the error bars 95% CI.

Figure 5. Kaplan-Meier Survival Curve

Survival curves for patients receiving initial trophic vs full-energy enteral nutrition. P=0.24