Human friendly control system of alveolar CO2-concentration based on adaptive control theory

The purpose of the present study is to construct a basic experimental system for automatic control of alveolar CO₂-concentration during controlled and assisted respiration. This system consists of a newly developed computer-controlled respirator and its controlling devices. In the present study, ventilation rate and alveolar CO₂-concentration are regarded as the input and output of the controlled object, respectively. The automatic control system of alveolar CO₂-concentration is designed using an adaptive pole-placement method. The proposed system is applied to clinically basic control experiments of alveolar CO₂-concentration both in controlled and assisted respiration. Furthermore, physiological experiments are made on healthy subjects during light exercise in order to ascertain the robustness of the system. Thus, the proposed system is confirmed to be useful for the control of alveolar CO₂-concentration taking into account characteristic differences of the respiratory regulation system due to chronic change and individuality