Validity of inspiratory and expiratory methods of measuring gas exchange with a computerized system.
The accuracy of a computerized metabolic system, using inspiratory and expiratory methods of measuring ventilation, was assessed in eight male subjects. Gas exchange was measured at rest and during five stages on a cycle ergometer. Pneumotachometers were placed on the inspired and expired side to measure inspired (VI) and expired ventilation (VE). The devices were connected to two systems sampling expired O(2) and CO(2) from a single mixing chamber. Simultaneously, the criterion (Douglas bag, or DB) method assessed VE and fractions of O(2) and CO(2) in expired gas (FE(O(2)) and FE(CO(2))) for subsequent calculation of O(2) uptake (VO(2)), CO(2) production (VCO(2)), and respiratory exchange ratio. Both systems accurately measured metabolic variables over a wide range of intensities. Though differences were found between the DB and computerized systems for FE(O(2)) (both inspired and expired systems), FE(CO(2)) (expired system only), and VO(2) (inspired system only), the differences were extremely small (FE(O(2)) = 0.0004, FE(CO(2)) = -0.0003, VO(2) = -0.018 l/min). 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.
Bassett
D R
DR
Department of Exercise Science and Sport Management, University of Tennessee, Knoxville, Tennessee 37996-2700, USA. DBassett@utk.edu
Howley
E T
ET
Thompson
D L
DL
King
G A
GA
Strath
S J
SJ
McLaughlin
J E
JE
Parr
B B
BB
D000328:Adult; D002245:Carbon Dioxide / Q000378:metabolism; D001330:Electronic Data Processing; D005080:Exercise Test; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D011659:Pulmonary Gas Exchange; D012143:Respiratory Physiological Phenomena; D013147:Spirometry / Q000379:methods*
D002245:Carbon Dioxide