James is a 19-year-old who was recently in a motor vehicle accident that occurred on a winding road as he was driving back from the coast after a weekend of surfing. He was admitted to the intensive care unit (ICU), intubated, and was receiving mechanical ventilation. Prognosis appeared guarded, but the treating team felt that they should consider if and when to commence enteral feeding. They wondered how many calories they should aim for if they go that route.
Cumulative energy deficit has been associated with adverse outcomes in critically ill patients. Current guidelines recommend that energy intake match energy expenditure. However, fewer than 60% of patients receive the recommended energy intake.
Investigators from the Australian New Zealand Intensive Care Society Clinical Trials Group compared the effect of energy-dense (1.5 kcal per milliliter) versus routine (1.0 kcal per milliliter) enteral nutrition on mortality in critically ill patients admitted to 46 Australian and New Zealand ICUs and receiving mechanical ventilation. Most of the 3957 patients were admitted for nonoperative causes. The target rate of feeding was 1mL/kg/hour, based on ideal body weight, with a maximum rate of 100mL/hour, and the primary outcome was all-cause mortality at 90 days.
Although the volume of daily enteral feeding received by the two study groups was similar, the energy-dense group received 100% of target calories and the routine-feeding group received 70% of target calories. At 90 days, the mortality rate did not differ significantly between the two groups (relative risk,1.05; 95% CI, 0.94–1.16; P=0.41). In analysis of predefined subgroups, both survival time and mortality at 90 days also did not differ significantly between the two groups. The energy-dense group experienced more vomiting.
In a NEJM Journal Watch summary of this study, pulmonary and critical care physician Patricia Kritek concluded, “These results support a de-emphasis on the push for ‘full’ enteral nutrition for mechanically ventilated patients in the medical intensive care unit. For this population, ‘some’ enteral feeding is just fine.”
Considering these findings, the treatment team for James decided that some enteral feeding as opposed to “full” enteral feeding would suffice.
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Angela is a 2018-2019 NEJM editorial fellow. She is an endocrine fellow who trained at Flinders Medical Centre and the Royal Adelaide Hospital. Angela recieved her medical degree from the University of Adelaide, and masters of public health from the University of Sydney. Her clinical and research interests are in the areas of glucocorticoid and cardiovascular endocrinology and diabetes medicine.