A hypnosis and analgesia control system using a model predictive controller in total intravenous anesthesia during day-case surgery

In this paper, a hypnosis and analgesia control system using a model predictive controller during total intravenous anesthesia for day-case surgery is developed. A new analgesia index for analgesia control is constructed from pulse rate and Entropy Difference (ED) obtained by spectral analysis of electroencephalogram (EEG). As the anesthetics propofol and remifentanil are used, and the Bispectral Index (BIS) and the proposed analgesia index are used as hypnosis and analgesia indices, respectively. The model of hypnosis and analgesia responses to propofol and remifentanil consists of pharmacokinetic models, pharmacodynamic models considering interaction of drugs, and dead times. The control system has an identification function of individual parameters of pharmacodynamic models and dead times, and adjusts infusion rates of propofol and remifentanil simultaneously using model predictive control after the identification. Simulation results show that it has a good performance, but the identification method of individual parameters has to be improved.