Comparison of indirect calorimetric measurements of resting energy expenditure with a ventilated hood, face mask, and mouthpiece.

This study compared three techniques for indirect calorimetric measurement of resting energy expenditure: ventilated canopy, face mask, mouthpiece plus noseclips. A total of 18 healthy men and women underwent all three measurement techniques in three consecutive 20-min measurement periods in a Latin square design. No significant effects were found for either period or method with respect to oxygen consumption, respiratory exchange ratio, and caloric expenditure. Oxygen consumption was (mean +/- SD) 250 +/- 45, 251 +/- 47, and 254 +/- 49 mL/min for hood, mask, and mouthpiece, respectively (ns). The respiratory exchange ratio was lower for the hood (0.809 +/- 0.051) than mask (0.837 +/- 0.043) and mouthpiece (0.847 +/- 0.045) but this difference was not statistically significant (p = 0.07). Calculated caloric expenditure was 1.20 +/- 0.22, 1.21 +/- 0.22, and 1.23 +/- 0.23 kcal/min for hood, mask, and mouthpiece, respectively (ns). Thus, in healthy individuals similar results are obtained by the three methods and the face mask and mouthpiece are acceptable alternatives to the ventilated hood for estimation of resting energy expenditure.