SmartPad, a Novel Device for Contactless Energy Expenditure Measurement

• Published in: Obesity (Silver Spring, Md.) Vol. 29; p. 163
• Main Authors: Sprowls, Mark, Mora, Jimena, Osorio-Perez, Oscar, Shaun, Victor, Pyznar, Gabriel, Destaillats, Hugo, Wheatley-Guy, Courtney, Johnson, Bruce, Kulick, Doina, zani, Erica
• Format: Journal Article
• Language: English
• Published: Silver Spring Blackwell Publishing Ltd 01-12-2021
• Subjects: Accuracy; Body mass index; Foreign exchange rates
• ISSN: 1930-7381; 1930-739X

Background: Energy Expenditure, a key diagnostic measurement for treatment of obesity, is measured via breath biomarkers of CO2 production (VCO2) and/or O2 consumption rates (VO2). Current technologies are limited due to prevailing designs requiring accessories that present usability concerns particularly in pandemic times. Methods: A novel system, named SmartPad, is evaluated in this work. The SmartPad is capable of performing contactless EE measurement via assessment of VCO2 measured from ambient CO2 concentration within a room. One hundred thirteen (N = 113) Resting EE (REE) and forty-six (N = 46) exercise energy expenditure measurements were performed with SmartPad and a reference instrument, the MGC Ultima CCMTM to study the influence of the EE measurement resolution on the accuracy of the EE measurement. Results: The SmartPad displayed an accuracy of 90 % (68% Confidence Interval (CI)) for 14-19 minutes of REE measurement, and an accuracy of 90% (68% CI) for 4.8-7.0 minutes of exercise EE when VCO2 measurement were extracted from the SmartPad after calibrating the room air exchange rate (X [h-1]) using the reference instrument. In addition, the SmartPad system was used to assess the REE of N = 5 subjects with a wide range of body mass indexes (BMI) for a minimum of 5 measurements each. These experiments demonstrated that the accuracy of SmartPad for determination of EE was kept regardless the subject's BMI or subject's REE (which varied from 1100 to 3300 kcal/day). Further, a high correlation between the subjects' VCO2 measurements (N = 26) and room air exchange rate X [h-1] measured during CO2 accumulation periods was found (P < .00001, R = 0.785) when a medium sized room was used. This observation led to development of a new model for REE measurement from ambient CO2, without the need of accounting for X extracted from reference instruments for that particular room. Conclusions: The new model rendered EE metrics from SmartPad that correlated in a nearly 100% with EE metrics from the reference instrument (y = 1.02x, R = 0.937) when an independent dataset (N = 56) was applied, indicating the passive and accurate EE assessment is possible with SmartPad system.