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160 - GAS ANALYSIS MODULE RESPONSE TIME
A major factor affecting breath-by-breath respiratory gas measurements is the response time of the O2100C and CO2100C modules. Although the CO2100C module has somewhat faster response times than the O2100C module, both can seemingly create obstacles when performing relatively high-speed breath-by-breath ventilation measurements.
Typically, the O2100C and CO2100C modules are used in conjunction with a mixing chamber and non-rebreathing "T" valve to measure varying gas concentration levels as a function of time. The mixing chamber and "T" valve effectively construct a smoothing filter for expired gases. Because the gas concentrations can change only gradually in this configuration, it is simple to monitor the changing oxygen and carbon dioxide levels present in the mixing chamber.
An alternate, and more difficult, measurement scenario is where oxygen or carbon dioxide concentrations need to be measured exactly, at particular points during a single respiration. In this case, it is very important that the module be able to keep up with the expected rate of change of gas concentration.
This application note will concentrate on methods to improve the response time of the O2100C module. When necessary, the same principles will apply to enhance the speed of the CO2100C module.
