Evaluation of a non-invasive method for the measurement of metabolic rate in humans

Measurements of oxygen consumption (VO2) and carbon dioxide production (VCO2) can be used to calculate energy expenditure. Such data are useful in the nutritional management of a variety of pathological conditions. This study is an evaluation in vitro and in vivo of the mating of a canopy and a Beckman metabolic measurement cart 1 (MMC). The canopy allows for the collection of expired gases without facial attachments. Studies in vitro demonstrated the necessity of calibrating the CO2 analyser at the concentrations used in such a system (0.50-0.80% CO2). Measurements of VO2 were within + 12% to -8% of predicted values, and when calibrated at 0.50% and 0.75% CO2, measurements of VCO2 were within + 2% and -7% of predicted values. The studies in vivo revealed that VO2 and VCO2 were within +/- 11% of the values obtained by using a canopy-spirometer-computer system. The MMC plus canopy may provide an alternative method for the clinical measurement of VO2 and VCO2, especially in subjects unable to tolerate a tight-fitting mask for prolonged periods.