Approximation of Resting Energy Expenditure in Intensive Care Unit Patients Using the SenseWear Bracelet: A Comparison With Indirect Calorimetry

BACKGROUND AND AIMS

Indirect calorimetry (IC) is the gold standard for determining energy expenditure in patients requiring mechanical ventilation. Metabolic armbands using data derived from dermal measurements have been proposed as an alternative to IC in healthy subjects, but their utility during critical illness is unclear. The aim of this study was to determine the level of agreement between the SenseWear armband and the Deltatrac Metabolic Monitor in mechanically ventilated intensive care unit (ICU) patients.

METHODS

Adult ICU patients requiring invasive ventilator therapy were eligible for inclusion. Simultaneous measurements were performed with the SenseWear Armband and Deltatrac under stable conditions. Resting energy expenditure (REE) values were registered for both instruments and compared with Bland-Altman plots.

RESULTS

Forty-two measurements were performed in 30 patients. The SenseWear Armband measured significantly higher REE values as compared with IC (mean bias, 85 kcal/24 h; P = .027). Less variability was noted between individual SenseWear measurements and REE as predicted by the Harris-Benedict equation (2 SD, ±327 kcal/24 h) than when IC was compared with SenseWear and Harris-Benedict (2 SD, ±473 and ±543 kcal/24 h, respectively).

CONCLUSIONS

The systematic bias and large variability of the SenseWear armband when compared with gas exchange measurements confer limited benefits over the Harris Benedict equation in determining caloric requirements of ICU patients.

Comparison of the GEM and the ECAL indirect calorimeters against the Deltatrac for measures of RMR and diet-induced thermogenesis

The Deltatrac™ II Metabolic Monitor (Datex-Ohmeda Inc.) is considered the standard reference machine in indirect calorimetry; however, it is no longer commercially available thus there is a need for new machines. The gas exchange measurement (GEM; GEM Nutrition Ltd) and the ECAL (Health Professional Solutions) are alternative measuring systems. The aim of this study was to compare the ECAL and GEM with Deltatrac for measures of RMR and the GEM to the Deltatrac for measures of diet-induced thermogenesis (DIT). Twenty healthy participants were tested on test day 1 (T1) and test day 2 (T2). RMR was measured in a randomised order for 30 min on the Deltatrac, the GEM and the ECAL. Following this, a 1553 kJ meal was consumed and DIT was measured on the Deltatrac and the GEM in alternating 15 min intervals for 4 h. The GEM reported consistently higher values than the Deltatrac for VO2, VCO2, RMR and fat oxidation (P < 0·005). The ECAL was significantly higher than the Deltatrac for measures of VO2, RMR, carbohydrate oxidation (T2) and respiratory quotient and fat oxidation (T1, T2) (P < 0·05). There were no significant differences within repeated RMR measures on the ECAL, the GEM or the Deltatrac. DIT measures were consistently higher on the GEM (T1) (P < 0·005); however, there were no significant differences between repeated measures. The findings suggest that while the GEM and the ECAL were not accurate alternatives to the Deltatrac, they may be reliable for repeated measures.