DEVELOPMENT OF PORTABLE DEVICE FOR MONITORING OXYGEN UPTAKE

Abstract

A system for making prolonged measurements of oxygen uptake without the use of mask or mouthpiece is described. A subject wears a hood through which air is drawn by a exhaust pump located on the end of hoses. The flow rate of main stream is measured by a pulsed wire flowmeter located between flexible hose and rigid hose. The flow rate is essentially constant during a run. One sample pump bypasses small amount of mixed air from the main stream. The other pump draws the room air. Two sample pumps operate alternatively at 2 min interval. The sample gas is dried by passing through molecular sieve desiccant and is delivered to in-line oxygen analyzer. Both signals of flow rate and oxygen concentrations of room air and mixed air are converted to digital quantities and then stores in memory devices at 5 min interval. All measuring devices were assembled to small package which the subject carries on his back. The weight was about 7 kg. The memory chip is removed from the device after experiment and oxygen uptake is estimated by connecting the memory chip to a microcomputer. This measurement compared favorably with measurement with Douglas bag collection and gas analysis.