Early isocaloric enteral nutrition in ICU linked to more GI problems

Last Updated: 2017-11-16

By Anne Harding

NEW YORK (Reuters Health) - Early, aggressive enteral nutrition does not improve outcomes in ventilated patients with shock, according to findings from the NUTRIREA-2 trial published in The Lancet.

And these patients were more likely to have digestive complications with enteral than parenteral early isocaloric nutrition, Dr. Jean Reignier of the Centre Hospitalier Universitaire Hotel-Dieu in Nantes, France, and colleagues found. "Parenteral nutrition is the route of choice for early feeding of severe critically ill patients," Dr. Reignier told Reuters Health by email. The findings were published online November 8.

Given the high risk of severe malnutrition in critically ill, mechanically ventilated patients, Dr. Reignier and his team note, guidelines suggest enteral feeding with 20 to 25 kcal/kg per day starting during the acute phase of illness. But there are little data beyond observational studies to support this approach, and some evidence that it may be harmful, according to the researchers. "Whether timing, route or dose of nutritional support affects the outcomes of critically ill patients remains unclear," they add.

One previous large study, the CALORIES trial, compared enteral and parenteral early nutrition in 2,400 ICU patients, and found no difference in outcomes between the two approaches (http://bit.ly/1GzBJTx).

The NUTRIREA-2 trial involved 2,410 patients at 44 French intensive care units (ICUs) who were on ventilation and vasopressor support for shock. Participants were randomly assigned to receive enteral or parenteral nutrition starting within 24 hours of intubation, at a normocaloric dose.

Patient enrollment ended early because an interim analysis found no differences in the study's primary endpoint of mortality by day 28 after randomization.

The two groups did not differ significantly in 28-day mortality or the cumulative incidence of ICU infections. However, patients on enteral nutrition were significantly more likely to experience vomiting (34% vs. 20%), diarrhea (36% vs. 33%), bowel ischemia (2% vs. <1%), and acute colonic pseudo-obstruction (1% vs. <1%).

"Current guidelines should be changed," Dr. Reignier told Reuters Health. "They rely upon studies with methodological flaws (retrospective, observational, few patients, not severely ill)." CALORIES and NUTRIREA-2 demonstrated that enteral is not better than parenteral feeding, he added, and is associated with more adverse effects including hypoglycemia and gut ischemia.

Future studies should investigate whether hypocaloric and hypoprotidic feeding may be linked to better outcomes compared to isocaloric feeding, Dr. Reignier said. "Indeed, studies indicated that hypocaloric feeding may be associated with improved autophagy, a key mechanism involved in cellular repair."

"In these really ill, shocked patients, full enteral feeding may not always be the best idea," Dr. Michael Casaer of University Hospitals and Catholic University Leuven in Belgium, who co-authored an accompanying commentary, told Reuters Health by telephone. "Sometimes enteral feeding can harm."

The longstanding observation that patients with improved nutritional intake have a better outcome is likely due in part to the fact that "patients who are less severely ill are easier to feed," he added.

Even if ICU patients don't take in nutrition, their bodies are breaking down their own tissue for energy and amino acids, so perhaps they don't need more calories, Dr. Casaer explained. "We believed that we could heal the patient faster by feeding them intravenously or by the stomach, but then in fact we might be bypassing this anorectic state and thereby suppressing autophagy," he said.

In his own hospital, Dr. Casaer said, patients receive no parenteral nutrition for their first week in the ICU, although they are given vitamins and trace elements to prevent depletion and, thereafter, refeeding syndrome.

SOURCES: http://bit.ly/2yzes85 and http://bit.ly/2zDRJLR

Lancet 2017.