This system is designed for the measurement of human respiratory response. This system has two kinds of functions. One is to control concentration of agent gas which is supplied to the subject and the other is to measure the respiratory response of the subject due to the change of inhaled gas contents.
The main apparatus is divided into two systems, the mechanical system and the electronic system. The mechanical system mixes air and agent gas to be supplied to the subject. The electronic system based on microcomputer controls gas contents and gathers data on the subject.
Air and agent gases are reserved in tanks at high pressure 100 kg/cm
2-150 kg/cm
2. Either CO
2 or N
2O may be selected for purposes of experiment and mixed by means of the gas mixer. In the decompression area, the pressure of those gases are set to 8 kg/cm
2-10 kg/cm
2 and they are sent to the mixing box through the control valve. Mixed gas which is supplied from gas mixing box flows into decompression area of the second stage. This stage supplies the gas of about 1 atm or a little higher pressure to the subject. The concentration of the agent gas during inspiration is checked every 0.1 second and compared with the program of gas concentration.
Signals from microcomputer are sent to the pulse motor which controls the valve. The measuring circuit checks the concentration of agent gas according to the program and samples a few kinds of data, such as inspired gas concentration, expired gas concentration, flow volume of expired gas, heart rate, etc. One of the experiments on 5% CO
2 inhalation showed, the process of wash-in and wash-out of carbon dioxide of the subject.
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