Development of expiratory CO2-concentration control system for regulation of autonomic nervous tone by the adaptive control method.

众所周知，CO^2对多种生理功能有深远的影响。为了在人工通风条件下调节动物呼气气体浓度，研制了一种新的控制系统。该系统由呼吸气体监测仪(Respina 1H26，NEC-San-Ei)、A/D转换器(Analog-Pro DMA，Canopus)、并行输入输出模块(PIO 16/16T(987)、COTEC)、阀门控制器(Tyokai-rika)、个人计算机(PC-9801MM2，NEC)和呼吸器组成。控制程序用BASIC语言编写，控制变量(O_2和CO_2浓度)、操作变量(阀门开启周期)和参考模型的输出在CRT上显示。通过引入数值协处理器(8087)，缩短了计算时间，从而使通风量达到60次/分钟。即使在跟踪改变的设定值期间吸入气体和呼出气体浓度颠倒的情况下，也可以通过以先前呼吸周期确定的固定间隔从瞬时气体浓度中采样来正确地控制变量。在麻醉、麻痹和人工开胸的猫上，该系统可将呼气CO_2浓度稳定地控制在+0.1%左右，并提供对新设定值的快速平稳跟踪。该系统将为研究自主神经功能提供一个有用的工具，通过控制许多“背景活动”之一，呼吸气体浓度。

Is is well known that CO^2 has a profound influences on many physiological func- tions. To regulate expiratory gas concentrations of animals under artificial ventilation, a new control system was developed. The regulation was performed by changing the opening periods of magnetic valves through which gases (CO_2 and O_2 were added to the inspired air using the discrete-time adaptive control method< Ther system was composed of a respiratory gas monitor (Respina 1H26, NEC- San-ei) a A/D converter (Analog-pro DMA, Canopus), a parallel input-output module (PIO 16/16T(987), Cotec), a valve controller (Tyokai-rika), a personal computer (PC-9801MM2, NEC) and a respirator. The control program is written in Basic, and controlled variables (O_2 and CO_2 concentrations)and manipulated variables (opening period of the valve) and output of the reference model were displayd on a CRT. By introducing a numerical co-processor (8087) computation time was shortened so that the ventilation rate up to 60/min could be employed. Even in circumstances that the inspired and expired gas concentrations were reversed during tracking a changed set point, correct controlled varbiables were dupplirf yo yhr vonytollrt by sampling from instantaneous gas concentrations at a fixed interval determined by previous respiratory cycles. In the anes- thetized, paralyzed and artificially ventrilated cats, this system could control expiratory CO_2 concentration within + 0.1% around a desired level in a steady state and provided fast and smooth tracking of a new set point. This system will provide a useful tool for studying autonomic functions by controlling one of many "background activities", the respiratory gas concentration.