A Smart System for the Contactless Measurement of Energy Expenditure.

Energy Expenditure (EE) (kcal/day), a key element to guide obesity treatment, is measured from CO production, VCO (mL/min), and/or O consumption, VO (mL/min). Current technologies are limited due to the requirement of wearable facial accessories. A novel system, the Smart Pad, which measures EE via VCO from a room's ambient CO concentration transients was evaluated. Resting EE (REE) and exercise VCO measurements were recorded using Smart Pad and a reference instrument to study measurement duration's influence on accuracy. The Smart Pad displayed 90% accuracy (±1 SD) for 14-19 min of REE measurement and for 4.8-7.0 min of exercise, using known room's air exchange rate. Additionally, the Smart Pad was validated measuring subjects with a wide range of body mass indexes (BMI = 18.8 to 31.4 kg/m), successfully validating the system accuracy across REE's measures of ~1200 to ~3000 kcal/day. Furthermore, high correlation between subjects' VCO and λ for CO accumulation was observed ( < 0.00001, R = 0.785) in a 14.0 m sized room. This finding led to development of a new model for REE measurement from ambient CO without λ calibration using a reference instrument. The model correlated in nearly 100% agreement with reference instrument measures ( = 1.06, R = 0.937) using an independent dataset (N = 56).