Use of metabolic monitors in a multidisciplinary Intensive Care Unit: A prospective pilot study of 20 patients

Caloric intake of critically ill patients are usually calculated using predictive equations. Recent advances in gas exchange measurements have the potential to estimate energy expenditure at the bedside and at different time periods.

Energy needs of critically ill patients were estimated over a period of 3 months using simplistic formula of 25 kcal/kg/day estimated energy expenditure (EEE), Harris-Benedict equation (HBE) (Basal energy expenditure [BEE]) and M-COVX™ metabolic monitor resting energy expenditure (REE) on day 4 of Intensive Care Unit (ICU) admission. Calculations based on HBE were taken as standard, and percentage errors (PE) were calculated for each patient for values derived from simplistic formula and metabolic monitor. Adequacy of nutritional intake in ICU was also assessed.

Metabolic monitor could be used in only 20/70 patients. The mean age of patients was 40 years, 65% were males, and average body mass index was 23.69 kg/m(2). Intermittent intolerance to feeds was reported in 50%. Values of REE and EEE were greater than BEE in 70% of patients. A significant difference was reported in values of PE of ≤20% and ≥30%; P = 0.0003 and 0.0001, respectively estimated using REE and EEE.

It is not feasible to use metabolic monitors in all patients. Variability in readings is large and further studies are needed to establish the validity of its measurements. Calculations using simplistic formulas are much closer to values obtained using HBE.