Automatic control of respiration to deal with difference of individual characteristics

Abstract

A clinical technology generally consistent with a difference of individuals is discussed on the basis of adaptive control theory taking into account the automatic control of alveolar CO2-concentration in both controlled- and assisted-respiration. An experimental system for this purpose is proposed which consists of a newly developed respirator and controlling and measuring devices. Its control system requires safe and accurate operation in the different experimental environments in controlled- and assisted-respiration, which are characterized by pattems of ventilatory rhythms. In order to satisfy both requirements, a control system is designed on the basis of an adaptive pole assignment method, which is capable of compensating characteristic and environmental changes of a controlled object. It yields, thus, a stable control of alveolar CO2-concentration dealing with some disorder of the equipment, mainly with the different characteristics of a respiratory regulation system inclusive of its individual difference such as nonlinearity and chronic change. From clinical experiments on healthy subjects, the performance of the control system is confirmed to follow-up a given desired alveolar CO2-concentration with assurance of its clinical safety. This kind of adaptive control is confirmed to lead to the useful concept and method for the control of an organic function relied upon its less exact recognition because of its time-varying and ambiguous characteristics.