Development of Ambulatory Oxygen Uptake Measurement System

研制了一种长时间监测摄氧量而不感到不适的装置。该系统所依据的原理是开放的流通系统。受试者戴着一个引擎盖，空气通过一个排气鼓风机吸入。氧气浓度由伺服控制的鼓风机保持恒定，因此流量基本上与氧气吸收率成正比。主气流的流量由安装在排气软管中的飞行时间流量计测量。用极限电流氧传感器测量氧浓度。表示流速和氧浓度的信号被数字化并存储在存储器中。所有的设备都组装在一个小包装（重量= 3公斤）中，受试者背在背上。每次实验结束后，从便携设备上取下存储芯片。将数据从存储器传输到微机，然后估计摄氧量趋势。系统对阶跃输入的响应约为30秒。与市售的氧气监测系统（Magna 88， P. K. Morgan, England）相比，在0.25至2.1 /min的摄氧量范围内，最大误差为满量程的7.2%。用该系统测得的运动人体摄氧量与常规氧监测仪测得的结果吻合较好（r=0.973, r=0.932）。这种便携式设备能够在不受干扰的情况下测量受试者在日常活动和开车时的摄氧量。

An apparatus for monitoring prolonged measurement of oxygen uptake without discomfort has been developed. The principle on which the system is based is the open flow-through system. The subject wears a hood through which air is drawn by an exhaust blower. Oxygen concentration is maintained constant by a servo-controlled blower, so that flow rate is essentially proportional to oxygen uptake. The flow rate of the main stream was measured by a time-of-flight flow-meter located in the exhaust hose. Oxygen concentration was measured by a limiting current oxygen sensor. The signals representing flow rate and oxygen concentration were digitized and stored in a memory. All of the equipment was assembled in a small package (wt= 3 kg) which the subject carries on his back. The memory chip was removed from the portable device after each experiment. Data were transferred from the memory to a microcomputer and then an oxygen uptake trend was estimated. Response of the system to a step input was about 30 s. Compared with a commercially available oxygen monitoring system (Magna 88, P. K. Morgan, England), the maximum error was 7.2% of full scale within the range of 0.25 to 2.1 1/min of oxygen uptake. The oxygen uptake of exercising human subjects measured with this system 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.