February 9, 2012

Cutting calories doesn’t reduce ventilator use: study

Cutting calories doesn’t reduce ventilator use: study

Ventilator-dependent ICU patients are fed through a tube in the stomach continuously, but it’s never been fully understood what the best form of nutrition is, how often patients should be fed or how much they should be given.

Vanderbilt, in conjunction with the other 11 centers in the NIH/NHILBI Acute Respiratory Distress Syndrome (ARDS) network, aims to answer these questions with the hope of improving the outcomes of patients with acute lung injury (ALI).

In a study published in the Journal of the American Medical Association this week, Vanderbilt researchers report that patients with ALI who were given lower-volume enteral (tube) feedings did not have better outcomes than those who received full feedings.

Participants were randomized to receive either lower-volume (trophic) or full enteral feeding for the first six days of the study. After day six, the care of all patients who were still on mechanical ventilators received full feeding protocol.

Trophic feeding consisted of about 400 calories per day while full feeding consisted of about 1,300 calories per day.

Prior to this study there was only observational data regarding the best amount to feed patients with lung injury who were on mechanical ventilators, said Todd Rice, M.D., M.Sc., assistant professor of Medicine and lead author on the JAMA study.

Todd Rice, M.D., M.Sc.

Todd Rice, M.D., M.Sc.

“Some studies showed if you fed more, patients had slightly better outcomes. Others showed if you fed less, they had better outcomes because feeding more causes some complications and drives inflammation, a big part of the illness,” Rice explained.

A smaller amount of food is thought to have beneficial effects on the intestines, causing them to secrete enzymes that increase blood flow, thereby protecting the integrity of intestinal membrane. Higher doses of nutrition can cause complications of diarrhea, vomiting or aspiration.

“People have spent a lot of time and effort trying to feed ICU patients what they think is the right amount of calories, and it’s hard to do,” Rice said. “Patients don’t tolerate huge feeds when they are that sick, and we spend a lot of time giving them medicines to help their gut move better, trying to get them to full feeds.

“We did all that without any real data that this was beneficial for them. We were looking to see if feeding them fully or a little bit was better and which improved outcomes in the patients.”

The results of the study indicate that in patients with ALI, initial trophic feeding for up to six days, compared with full enteral feeding, did not improve ventilator free days, 60-day mortality or infectious complications, but it was associated with fewer gastrointestinal problems, according to the JAMA article.

Rice presented his findings at the Critical Care Congress in Houston, Texas earlier this week.