Abstract
This study compared gas exchange measurements obtained by using a mask, mouthpiece, and ventilated canopy in 30 normal, healthy volunteers. The ventilated canopy and its gas analyzers had an accuracy for oxygen consumption of 98.0 ± 0.8% and for carbon dioxide production of 100.1 ± 1.1%. The study indicates that the apparatus used for gas exchange measurement will significantly affect the measurements. The magnitude of the effect is a significant 7.9% increase for oxygen consumption with a mouthpiece and a significant 7.1% increase with a face mask. Carbon dioxide production was significantly increased 10.2% with a mouthpiece and 4.1% with a face mask. There were no differences in the respiratory quotient. The specific purpose for collecting gas exchange measurements will determine whether these differences are of practical significance. (Journal of Parenteral and Enteral Nutrition 17:388-391, 1993)
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