Ambulatory oxygen uptake measurement system.
An apparatus for monitoring prolonged measurement of oxygen uptake without discomfort has been developed. The system is based on the open flow-through principle. The subject wears a hood through which air is drawn by an exhaust blower. Oxygen concentration is kept constant by a servo-controlled blower, so that flow rate is essentially proportional to oxygen uptake. The flow rate of the main stream is measured by a time-of-flight flowmeter located in the exhaust hose. Oxygen concentration is measured by a limiting-current oxygen sensor. The signals representing flow rate and oxygen concentration are digitized and stored in a memory. All of the equipment is assembled in a small package (wt = 3 kg) which the subject carries on his back. The memory chip is removed from the portable device after each experiment. Data are transferred from the memory to a microcomputer and then an oxygen uptake trend is estimated. Response of the system to a step input is about 30 s. Compared with a commercially available oxygen monitoring system (Magna 88, P. K. Morgan Ltd., Rainham, UK), the maximum difference was 0.15 L/min within an oxygen uptake range of 0.25-2.3 L/min. Thus, the measurements made with our portable device agree with the results obtained using the conventional method.
Tamura
T
T
Department of Electrical and Electronic Engineering, Yamaguchi University, Japan.
Sato
K
K
Togawa
T
T
D000328:Adult; D002138:Calibration; D001330:Electronic Data Processing / Q000295:instrumentation; D004867:Equipment Design; D005069:Evaluation Studies as Topic; D006801:Humans; D008297:Male; D008433:Mathematics; D008838:Microcomputers; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D010100:Oxygen / Q000032:analysis; D010101:Oxygen Consumption; D012212:Rheology / Q000295:instrumentation
D010100:Oxygen