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

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 ≥48h and anticipated to remain in ICU≥5days 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.