Trial of the Route of Early Nutritional Support in Critically Ill Adults

Study Questions:

Is delivery through the parenteral route superior to that through the enteral route for delivery of early nutritional support in critically ill adults?


The CALORIES trial authors conducted a pragmatic randomized trial involving adults with an unplanned admission to one of 33 English intensive care units. They randomly assigned patients who could be fed through either the parenteral or the enteral route to a delivery route, with nutritional support initiated within 36 hours after admission and continued for up to 5 days. Parenteral nutrition was provided via a central venous catheter and enteral via a nasogastric or nasojejunal tube. The primary outcome was all-cause mortality at 30 days.


A total of 2,388 patients (99.5% of enrolled) were included in the analysis (1,191 in the parenteral group and 1,197 in the enteral group). Mean age was 63 years, 83% were on mechanical ventilation, and median predicted risk of death was 0.34 in each group. By 30 days, 393 of 1,188 patients (33.1%) in the parenteral group and 409 of 1,195 patients (34.2%) in the enteral group had died (relative risk in parenteral group, 0.97; 95% confidence interval, 0386-1.08; p = 0.57). There were significant reductions in the parenteral group, as compared with the enteral group, in rates of hypoglycemia (3.7% vs. 6.2%; p = 0.006) and vomiting (8.4% vs.16.2%; p < 0.001). There were no significant differences between the parenteral group and the enteral group in the mean number of treated infectious complications (0.22 vs. 0.21; p = 0.72), 90-day mortality (37.3% vs. 39.1%, p = 0.40), in rates of 14 other secondary outcomes, or in rates of adverse events. Caloric intake was similar in the two groups, with the target intake not achieved in most patients.


The authors concluded that there is no significant difference in 30-day mortality associated with the route of delivery of early nutritional support in critically ill adults.


This well-designed and difficult study addressed an important and controversial subject to both the providers and patients. For those unfamiliar with the term, pragmatic research asks whether an intervention works under real-life conditions and whether it works in terms that matter to the patient. In contrast, explanatory trials are conducted in highly selected cohorts with the intention of identifying how and why it works.

Clinical Topics: Prevention, Diet

Keywords: Parenteral Nutrition, Intensive Care Units, Vomiting, Adult, Central Venous Catheters, Nutritional Support, Intubation, Gastrointestinal, Respiration, Artificial, Critical Illness, Energy Intake, Hypoglycemia

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