[Intensive care patients. Determining daily energy expenditure - a comparison of two methods]

Using indirect calorimetry (IC), required energy demand may be determined. The SenseWear (SW) armband uses skin temperature, galvanic skin response, heat flux, and a 2-axis accelerometer to estimate daily energy expenditure (EE). The aim of the present study was to evaluate accuracy of the SenseWear measurements in critically ill and ventilated patients.

After approval of the local ethics committee and written informed consent, critically ill and ventilated patients were enrolled. During a 24-h study period EE was continuously measured using the SW armband (standardized position at right upper arm); an IC was performed additionally. Measurement bias (DeltaEE) was calculated as DeltaEE=EE(SW)-EE(IC). Daily energy expenditure of both techniques (IC vs. SW) was compared using regression analysis and the Bland Altman method. The t-Test for paired samples was used for statistical analysis, p<0.05 was considered statistically significant.

In total, 23 critically ill and ventilated patients (17 male, 6 female; means: 59.9+/-17.3 years; body mass index 28.0+/-6.3 kg/m(-2)) were investigated. A mean bias of DeltaEE=-565.65+/-1,748.07 kJ (-135.0+/-417.2 kcal) [range: -4,709.56+/-2,224.89 kJ (-1,124 to +531 kcal); p=0.3547] was calculated. Bland-Altman analysis revealed that SW slightly overestimates IC energy expenditure for critically ill patients in the hypo- and normocaloric range [<7,123 kJ/24 h: DeltaEE=+644.42+/-1,038.70 kJ (<1,700 kcal/24 h: DeltaEE=+153.8+/-247.9 kcal); p=0.0838], but significantly underestimated IC values in the hypercaloric range [>10,056 kJ/24 h: DeltaEE=-2,679.09+/-1,698.63 kJ (>2,400 kcal/24 h: DeltaEE=-639.4+/-405.4 kcal); p=0.0098].

The SenseWear armband is non-invasive, convenient and easy to handle, but has a significant measurement bias in the hypercaloric range. Although IC is still best suited to determining metabolic need in intubated patients, measurements with the SenseWear armband provide significant advantages, e.g. in non-intubated patients, and give a fair estimation of daily energy expenditure when used alone.