Study on automatic control of hypnosis using inhalational anesthetics

在这项研究中，开发了一个控制系统，调整吸入麻醉剂七氟烷的吸入浓度，基于双频指数，一个众所周知的催眠指数，以实现患者所需的麻醉。迄今为止，在通过吸入麻醉剂进行麻醉期间，通常基于呼出气体浓度来施用药物的量。但是，为了实现所需的麻醉，即使同时使用静脉和吸入麻醉药，也必须根据患者的催眠状态调整吸入浓度。为此，我们研究（1）一个模型的麻醉剂的影响，代表他们的相互作用，（2）催眠控制方法和识别方法的个人参数，和（3）致动器用于调整吸入麻醉剂的吸入浓度。所得结果如下。(1)一种可代表丙泊酚（静脉麻醉剂）和七氟烷相互作用的新型药效学模型。这架飞机已经 关于我们 只有8个参数，4个丙泊酚药效学模型参数和4个七氟烷药效学模型参数。模拟结果证实，当参数设置适当时，该模型描述了丙泊酚和七氟醚的作用和相互作用。(2)考虑到药物效应的延迟时间和七氟醚吸入浓度的上下限，建立了一种使用丙泊酚和七氟醚维持催眠在期望水平的模型预测控制方法。建立了基于麻醉诱导期实测数据的个体药效学参数和延迟时间的辨识方法。催眠控制在识别之后开始。仿真结果表明，所开发的控制系统可以保持在一个适当的范围内的催眠。(3)研制了一种用于调节七氟醚吸入浓度的安装式致动器样机。当安装致动器时，医生可以以通常的方式调节浓度。少

In this study, a control system is developed that adjusts inspired concentration of sevoflurane, an inhalational anesthetic, based on Bispectral Index, a well-known hypnosis index, to realize a desired anesthesia for patients. Up to now, during anesthesia by an inhalational anesthetic the amount of the drug is usually administered based on exhaled breath concentration. But to realize a desired anesthesia the inspired concentration has to be adjusted based on patient's hypnosis even when both intravenous and inhalational anesthetics are used. For this purpose we study (1) a model of the effects of anesthetics that represents their interaction, (2) a hypnosis control method and an identification method of individual parameters, and (3) an actuator for adjusting inspired concentration of the inhalational anesthetic. The obtained results are as follows.(1) A novel pharmacodynamic model that can represent the interaction of propofol, an intravenous anesthetic, and sevoflurane. The model has … More only eight parameters, four parameters of the propofol pharmacodynamic model and four parameters of the sevoflurane pharmacodynamic model. Simulation results confirm that the model describes the effect and the interaction of propofol and sevoflurane when the parameters are set appropriately.(2) A model predictive control method for maintaining hypnosis at a desired level using both propofol and sevoflurane is constructed considering delay times of drug effects and upper and lower bounds of inspired concentration of sevoflurane. An identification method of individual pharmacodynamic parameters and delay time based on measured data during anesthesia induction is also developed. The hypnosis control is started after the identification. Simulation results confirm that the developed control system can keep hypnosis within a proper range.(3) A prototype of a mounting actuator for adjusting inspired concentration of sevoflurane is developed. Medical doctors can adjust the concentration in the usual way when the actuator is mounted. Less