Development and evaluation of the ambulatory relative metabolic rate (RMR) realtime monitoring system

Abstract

Development of an ambulatory RMR monitoring system for evaluating the physical work-load is presented. This system can be used under special conditions where it is difficult to use the traditional "Douglas" method. The main features of this system are: Using an improved turbin-spirometer to measure expiratory gas volume, data-processing procedure is simplified by converting a 0.1 iota expiratory gas volume to an electric pulse signal. Utilizing a Galvanic-cell type sensor, a kind of porlarograph electrode, to measure oxygen concentration in expiratory gas, the temperature of the electrode is maintained constantly at 40 degrees C in order to stabilize the output of the sensor against change in environmental and expiratory gas temperature. To improve the accuracy measurement of oxygen concentration and to prevent the teflon membrane at the top of the electrode from chilling and vibrating by direct expiratory gas flow, the bypass stream line is led to the electrode and a small portion of expiratory gas is introduced to measure oxygen concentration. It is possible to measure the time-sequential RMR value for several hours by minimizing and lightening the measuring instruments. It is possible to measure the time-sequential changing characteristics of the physical work-load (RMR), heart rate, breathing rate, and skin temperature under the actual work environment by a telemetring or portable recording method.