NEW YORK (Reuters Health) – In a randomized, single-center study of critically ill patients in an intensive care unit, permissive enteral underfeeding was associated with lower morbidity and mortality than target enteral feeding.

The appropriate caloric intake for critically ill patients remains “ill defined,” Dr. Yaseen Arabi and colleagues from King Saud Bin Abdulaziz University, Riyadh, Saudi Arabia, note in the January 26 online issue of the American Journal of Clinical Nutrition. Some studies have suggested that a lower caloric intake may yield better outcomes, while others have found the opposite.

To investigate further, they randomly assigned a group of critically ill patients to permissive enteral underfeeding, with a target caloric goal of 60% to 70% of calculated requirement, or target enteral feeding, where the target caloric goal was 90% to 100% of calculated need.

Data analysis was based on a total of 240 patients who were fairly evenly split between the four groups and were well-matched for baseline characteristics.

Hospital mortality rate was significantly lower in the underfeeding arm than the target feeding arm (30.0% vs 42.5%; relative risk 0.71: P < 0.04). The 28-day all-cause mortality rate (the primary endpoint) was also lower, although not statistically so, in the underfeeding group than the target feeding group (18.3% vs 23.3%; relative risk 0.79; P = 0.34). The same was true for the 180-day mortality rate (32.8% vs 44.4%; relative risk 0.77; P = 0.07). The researchers say several factors might account for the lack of a statistically significant difference in the 28-day mortality rate — chief among them is the achieved caloric intake, especially in the target group, which was below what was planned (71% versus a planned target of 90% to 100%). This resulted in a smaller difference between interventions (59% vs 71%). It’s also possible that the permissive underfeeding target of 60% to 70% was not hypocaloric enough and that lower caloric intake may produce a benefit, as has been shown in one observational study. As part of the study, subjects received either intensive insulin therapy or conventional insulin therapy, with target blood glucose levels of 4.4 to 6.1 mmol/L and 10 to 11.1 mmol/L, respectively. According to the investigators, there were no significant differences in outcomes with intensive or conventional insulin therapy and intensive insulin therapy was associated with a significant increase in the risk of hypoglyemia. They say the lack of benefit from intensive insulin therapy “raises the question of what the optimal blood glucose concentration is in critically ill patients and whether other factors, such as glucose variability, are as important.” Reference:
Permissive underfeeding and intensive insulin therapy in critically ill patients: a randomized controlled trial

Am J Clin Nutr 2011. Published online January 26, 2011.