That finding was reported online February 5 by the Journal of the American Medical Association, to coincide with a presentation at the Critical Care Congress.
The authors explain that the nutritional needs of mechanically ventilated patients with acute lung injury are unclear. Several studies have indicated improved outcomes in patients receiving a high percentage of calculated caloric requirements, but recent data have suggested that underfeeding may be beneficial.
To try to resolve these conflicting strategies, Dr. Todd W. Rice, with Vanderbilt Medical Center in Nashville, Tennessee, and colleagues conducted a randomized trial comparing full enteral feeding versus minimal “trophic” enteral nutrition for the first 6 days of mechanical ventilation in 1000 patients with acute lung injury at 44 hospitals.
The trophic-feeding group received about 400 kcal per day, representing 25% of their calculated caloric goal, while the full-feeding group received approximately 1300 kcal per day, or 80% of the calculated caloric goal, the report indicates. After day 6, all patients received the full feeding protocol.
The team hypothesized that initial trophic feeding, by reducing instances of GI intolerance, would lead to an increase in the number of ventilator-free days by day 28. In fact, they found there was no difference between groups: there were 14.9 ventilator-free days in the trophic-feeding arm versus 15.0 in the full-feeding arm.
There was also no difference in 60-day mortality in the two groups (23.2% vs 22.2%, respectively) or in the incidence of ventilator-associated pneumonia (7.3% vs 6.7%) or bacteremia (11.6% vs 9.3%), Dr. Rice and colleagues report.
Summing up, they conclude, “Contrary to previous reports in critically ill adults, hypocaloric nutrition did not significantly reduce mortality, decrease infectious complications, or reduce lengths of stay.”
In a related commentary, Dr. Richard D. Griffiths at the University of Liverpool, UK, comments that the results do not necessarily mean that trophic feeding is equivalent to full feeding in critically ill patients.
“This study was not designed or powered as an equivalence study,” he points out, “and does not provide definitive data to inform clinicians about how much nutritional support is enough, how early it should be started, or even if there should be ‘no nutrition provision’ in the initial phase of critical illness – a case that has been persistently argued and remains to be tested.”