![]() ![]() Expired ventilation (V˙ e) values were calculated using the Haldane transformation of the Fick equation ( 5, 6, 13). In the 1960s, with the development of the Parkinson-Cowan dry gas meter, the measurement of inspired minute ventilation (V˙ i) became common. The Douglas bag method has served as the “gold standard” for gas exchange measurements for over a century. This involved the collection of exhaled air in large, impermeable canvas bags and subsequent measurement of gas fractions and expired volumes ( 4). Historically, gas exchange was measured by the Douglas bag method. The measurement of O 2 consumption (V˙ o 2) by open-circuit spirometry is one of the fundamental measures in the field of exercise physiology. ![]() Thus a computerized system, using inspiratory or expiratory configurations, permits extremely precise measurements to be made in a less time-consuming manner than the DB technique. Though differences were found between the DB and computerized systems for F e O 2 (both inspired and expired systems), F e CO 2 (expired system only), andV˙ o 2 (inspired system only), the differences were extremely small (F e O 2 = 0.0004, F e CO 2 = −0.0003,V˙ o 2 = −0.018 l/min). Both systems accurately measured metabolic variables over a wide range of intensities. Simultaneously, the criterion (Douglas bag, or DB) method assessed V˙ e and fractions of O 2and CO 2 in expired gas (F e O 2and F e CO 2) for subsequent calculation of O 2 uptake (V˙ o 2), CO 2 production (V˙ co 2), and respiratory exchange ratio. The devices were connected to two systems sampling expired O 2 and CO 2 from a single mixing chamber. Pneumotachometers were placed on the inspired and expired side to measure inspired (V˙ i) and expired ventilation (V˙ e). Gas exchange was measured at rest and during five stages on a cycle ergometer. The accuracy of a computerized metabolic system, using inspiratory and expiratory methods of measuring ventilation, was assessed in eight male subjects. ![]()
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