Relevance of non-nutritional calories in mechanically ventilated critically ill patients

Overfeeding in critically ill patients is associated with many complications. Propofol, dextrose infusion and citrate dialysis provide non-nutritional calories (NNCs), potentially causing overfeeding. The relevance of NNCs for total caloric intake has not been systematically studied.

We retrospectively studied adult mechanically ventilated intensive care unit (ICU) patients receiving enteral nutrition with or without supplemental parenteral nutrition. Primary outcome was the proportion of NNCs (from dextrose, propofol and trisodium citrate) to the total energy intake during the first 7 days after ICU admission. In addition, NNC intake groups were compared.

In total, we identified 146 patients: 142 patients with NNC median value of 580 kcal (interquartile range 310-1043 kcal) over 7 days and 4 patients without NNC intake. The mean proportion of NNCs was larger during the first days after ICU admission (30.7-36.1%), because of the start-up phase of the nutrition. In the 'propofol' group and the 'dextrose' group this proportion levelled off at 6% on day 4. A more stable proportion of 18% was found during the first 7 days of ICU admission in the 'citrate' group.

The mean proportion of NNCs in patients who receive dextrose and/or propofol is low (6%); however, in individual patients it may comprise one-third of the total daily calories. Patients receiving trisodium citrate have higher mean non-nutritional intakes (18%). As NNC intake can be marked in individual patients, close monitoring is warranted when administering high-dose propofol or trisodium citrate anticoagulation to prevent overfeeding.