Measurement of physical activity levels in the Intensive Care Unit and functional outcomes: An observational study

Abstract Purpose Primary aims were: (1) objectively quantify levels of physical activity with the sensewear armband mini-fly motion sensor (SWA-MF), (2) evaluate the correlation of SWA-MF measurement of active and resting energy expenditure against the ICU Mobility scale (IMS) and indirect calorimetry respectively. Materials and methods Adults mechanically ventilated ≥ 48 h and anticipated to remain in ICU ≥ 5 days were included. Physical activity (PA) was measured using a SWA-MF (over the first five days); energy expenditure was measured with both the SWA-MF and the Deltatrac II metabolic cart on day three; highest level of mobility was assessed on the IMS. Results Fifty-five participants performed median [IQR] 16.8 [0.6–152.4] minutes of PA per day (defined as > 1.0 metabolic equivalent). A strong correlation between active energy expenditure and highest level of mobility (IMS), r = 0.76, p = 0.00 was observed on day 5. The SWA-MF demonstrated moderate to good agreement with the Deltatrac II metabolic cart (n = 20), intra-class correlation co-efficient = 0.71 (p = 0.00) for the measurement of energy expenditure on day 3. Conclusions Participants demonstrated low levels of PA. Motion sensors may be a promising non-invasive measure of energy expenditure and further investigation is warranted.