Evaluation of ambulatory oxygen uptake monitor / 体力科学

ABSTRACT

A portable device for long-term monitoring of oxygen uptake without discomfort has been developed based on a flow-through principle. The oxygen content of the exhaust gas was kept constant by a servo-controlled blower, so that the flow rate was essentially proportional to the oxygen uptake. This system was evaluated by both a bench test and in exercising human subjects. The limiting current-type oxygen sensor used this portable device produced results which were in good agreement those obtained using a zirconia oxygen sensor (r= 0.999), and stable values were obtained for at least 15 h. The response time for a stepped oxygen change was 4 s. The air flow rate produced by the blower was proportional to the supplied voltage. The results using a time-of-flight flowmeter were highly correlated with those for a hot-wire anemometer (r=0, 999) . The oxygen uptake of exercising human subjects measured with this portable device showed good agreement with that obtained by a conventional oxygen monitor (r=0.973 for cycle ergometer, r=0, 932 for treadmill) . This portable device was able to measure oxygen uptake in subjects during daily activities, and also while driving a car, without disturbance.