A validation study of the Q-Plex I cardiopulmonary exercise system
Abstract
A total of 27 Ss from the University of Wisconsin-La Crosse, ages 19-34
yrs, volunteered to participate in the validation study of the Q-Plex I
Cardiopulmonary Exercise System developed by the Quinton Instrument
Company. Each S performed a constant speed, grade incremented treadmill
test to volitional exhaustion. Simultaneous measurements of expired air
ware performed with the Q-Plex and a meteorological balloon gas
collection system to determine the validity of the Q-lex. Respiratory
and metabolic assessments were made during at least 3 different levels
of exercise; low steady state, medium steady state, and at maximal
exertion. A total of 93 gas samples were collected and analyzed by the
2 methods. The means for FeO2 and FeCO2 were significantly (p0.85)
different. However, the absolute mean differences were only 0.5% for FeO2
and 0.3% for FeCO2 which are within the accuracy of the reported error for
the analyzers. These results indicated that the Q-Plex gas analyzers
are as accurate as the micro-Scholander technique. Correlation
coefficients between the 2 systems were .9735 for FeO2 and .9729 for
FeCO2. After all the validation data were collected a final comparison
was mule between a series of volumes obtained with the Parkinson-Cowan
meter and the Tissot spirometer. These results indicated there was a
much larger discrepancy in volumes obtained between these methods than
those initially reported. These differences were of sufficient
manitude to question the accuracy of using this meter to validate the
volumes obtained with the Q-Plex. Since it was impossible to determine
the cause of this error, or at what point in the study it occurred, the
VE volumes of the Q-Plex could not be legitimately validated using the
Parkinson-Cowan meter. Unfortunately, since the accuracy of measuring
VO2 and VCO2 is dependent upon VE volumes, neither of these volumes
could be compared. Within the limitations of the present study, it was
concluded that the gas analyzers in the Q-Plex demonstrate accuracy
comparable to that of the micro-Scholander technique.
Subject
Pulmonary function tests - Validity
Treadmill exercise tests - Validity
Pulmonary gas exchange
Q-Plex I Cardiopulmonary Exercise System