Enteral vs Parenteral Nutrition in Critical Care Requiring Mechanical Ventilation

enteral nutrition
enteral nutrition
Enteral nutritional support was not clinically superior to parenteral nutritional support in critically ill patients receiving mechanical ventilation.

Enteral feeding was not superior to parenteral feeding for early nutritional support in critically ill patients receiving mechanical ventilation and vasopressor support for shock, according to the results of a study published in The Lancet.

Acute critical illness requiring mechanical ventilation carries a risk for severe malnutrition. Jean Reignier, MD, professor at the Universite de Nantes in France, and colleagues explored whether early first-line enteral nutrition would result in better outcomes than early parenteral nutrition.  

The investigators designed a randomized, controlled, multicenter, open-label, parallel-group trial (NUTRIREA-2; ClinicalTrials.gov identifier: NCT01802099), which was conducted at 44 French intensive care units (ICUs). 

Adults receiving mechanical ventilation and vasopressor support for shock were randomly assigned to either parenteral or enteral nutrition within 24 hours of intubation. Both regimens targeted normocaloric levels (20-25 kcal/kg/d). The primary end point was mortality on day 28 after randomization.

Between March 22, 2013 and June 30, 2015, 2410 patients enrolled in the trial and were randomly assigned: 1202 to the enteral group and 1208 to the parenteral group. By day 28, 37% of the enteral group and 35% of the parenteral group had died (absolute difference estimate, 2%; 95% CI, –1.9 to 5.8; P =.33). The cumulative incidence of ICU-acquired infection did not differ significantly in either group: 14% in the enteral group and 16% in the parenteral group (hazard ratio [HR], 0.89; 95% CI, 0.72-1.09; P =.25). 

However, compared with the parenteral group, patients in the enteral feeding group had higher cumulative incidences of vomiting (34% vs 24% in the enteral and parenteral groups, respectively; HR, 1.89; 95% CI, 1.62-2.20; P <.001), diarrhea (36% vs 33%, respectively; HR, 1.20; 95% CI, 1.05-1.37; P =.009), bowel ischemia (2% vs <1%; HR, 3.84; 95% CI, 1.43-10.3; P =.007), and acute colonic pseudo-obstruction (1% vs <1%; HR, 3.7; 95% CI, 1.03-13.2; P =.04).

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One limitation of the study was that after the second interim analysis it was prematurely discontinued as the independent Data Safety and Monitoring Board determined that further patient recruitment was unlikely to significantly change the results. However, 84% of the patients required according to the sample size estimation were included, and the results of the final analysis were in accord with those of both prior interim analyses.

The investigators concluded that the enteral route is not clinically superior to the parenteral route for early nutritional support in critically ill patients receiving mechanical ventilation and vasopressor support, and may increase the risk for gastrointestinal complications in this patient population.


Reignier J, Boisrame-Helms J, Brisard L, et al. Enteral versus parenteral early nutrition in ventilated adults with shock: a randomised, controlled, multicentre, open-label, parallel-group study (NUTRIREA-2). Lancet. 2018;391:133-143.