RESUMO
BACKGROUND & AIMS: Metabolic carts used in laboratory settings for the measurement of resting metabolism are cumbersome limiting their use in the field. The validity of a newly developed portable calorimeter (Medical Graphics VO2000) under resting conditions was assessed in comparison to a well-established reference system, the DELTATRAC. METHODS: Gas exchange and energy expenditure were measured for 25 min consecutively using the two devices. Values of the last 20 min were averaged and used in the analysis. The order of device for the first subject was randomly chosen and the calorimeters were alternated thereafter. RESULTS: Among 33 subjects, acceptable measures of resting metabolism were obtained in 25 (11 men) aged 20-78 years because eight subjects (three men) either hyperventilated or did not adapt well enough to the facemask. VO(2), VCO(2), and RQ were not significantly different between devices. Small (2.8%) non-clinically relevant mean differences (-0.145+/-0.341 MJ day(-1)) were found. Results of the two devices were highly correlated (r=0.95) yielding a more accurate estimate than predictive equations. CONCLUSIONS: The VO2000 calorimeter is a valid system to measure resting metabolism but the facemask may not be suitable for some people.