Journal of Applied Physiology, Vol 66, Issue 1 492-497, Copyright © 1989 by American Physiological Society
A prototype gas exchange monitor for exercise stress testing aboard NASA Space Station
J. A. Orr, D. R. Westenskow and A. Bauer
Department of Anesthesiology, University of Utah, Salt Lake City 84132.
A monitor was developed to track weightlessness deconditioning aboard the
National Aeronautics and Space Administration (NASA) Space Station by
measuring the O2 uptake (VO2) and CO2 production (VCO2) and calculating
maximum VO2 and anaerobic threshold during an exercise stress test. The
system uses two flowmeters in series to achieve a completely automatic flow
calibration, and it uses breath-by-breath compensation for sample line
transport delay. The accuracy of the system was measured over the range of
VO2 and VCO2 from 100 to 800 ml/min by means of simulation. Accuracy was
0.54% for VO2 and 2.9% for VCO2. The system was further evaluated using two
laboratory methods, the first method being comparison with a
breath-by-breath system. As volunteers performed a maximum effort on a
cycle ergometer, the mean difference in readings between the two systems
was 17 ml/min for VO2 and 8.0 ml/min for VCO2. The correlation coefficient
squared was greater than 0.96 for both. The second laboratory test was to
use the system for 2 mo in a Human Performance Laboratory. Readings of
maximum VO2 (VO2max) and anaerobic threshold were repeatable and consistent
with the individual's activity level. The accuracy and convenience of
operation will make this a valuable instrument aboard the Space Station.
