Indirect calorimetry using a ventilated hood may be easier than using a facemask to achieve steady state when measuring resting energy expenditure.

Previous studies have demonstrated differences in subjective comfort between different gas collecting methods during resting energy expenditure (REE) measurement. We hypothesized that gas collecting methods may have an influence on the time to achieve steady state and the optimum abbreviated period to estimate REE. Gas exchange variables were obtained using IIM-IC-100 (ventilated hood) and VO2000 (facemask) alternately among 32 healthy adults. A 10-minute test period was divided into 5-minute sliding time windows to obtain a subtle profile process of the coefficient of variation (CV) and REE. Friedman's test was used to compare the CVs during the test process. To compare the REE between abbreviated measurements and the reference, paired t test, linear regression, and Bland-Altman test were used. There were no significant differences between the CVs in each adjacent group of 5-minute intervals for IIM-IC-100 (P = .896). CV1 and CV2 were significantly higher than CV3-CV6 for VO2000 (P = .001). The proportion of subjects achieving steady state was lower with VO2000 (59.4-81.3%) than with IIM-IC-100 (84.4-91.8%). REE of the 2nd and 3rd 5-minute intervals did not differ from the reference, and they explained 94.7% (P < .001) and 94.9% (P < .001) of the last 5-minute REE variance, with the 95% limits of agreement ranging from -100.0 to 139.2 kcal/d and -139.5 to 182.5 kcal/d for IIM-IC-100 and VO2000, respectively. In conclusion, using a ventilated hood may be easier than using a facemask to achieve steady state and reduce the time required to estimate REE.