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

众所周知，CO^2对许多生理功能有着深远的影响。为调节人工通气条件下动物呼出气体浓度，研制了一种新型控制系统。该调节是通过改变电磁阀的开启周期来实现的，（使用离散时间自适应控制方法将CO_2和O_2添加到吸入的空气中。该系统由呼吸气体监测器（Respina 1H 26，NEC-San-ei）和A/D转换器（ADC）组成。（Analog-pro DMA，Canopus）、并行输入-输出模块（PIO 16/16 T（987），Cotec）、阀控制器（Tyokai-rika）、个人计算机（PC-9801 MM 2，NEC）和呼吸器。控制程序用Basic语言编写，控制变量（O_2和CO_2浓度）、操纵变量（阀门开启时间）和参考模型的输出均显示在CRT上。通过引入一个数字协处理器（8087），计算时间缩短，使通风量可达60/min。即使在吸入和呼出气体浓度在跟踪改变的设定点期间被反转的情况下，通过以由先前呼吸周期确定的固定间隔从瞬时气体浓度采样，正确的受控变量被复制。在麻醉、麻痹和人工通气的猫中，该系统可将呼气CO_2浓度控制在所需水平的± 0.1%以内，并能快速、平稳地跟踪新的设定值。该系统将通过控制许多“背景活动”之一，呼吸气体浓度，为研究自主神经功能提供有用的工具。

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.