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Modeling and Closed Loop Control of Hypnosis by means of Bispectral Index (BIS) with Isoflurane


A. Gentilini, M. Rossoni, M. Gerosa, C. Frei, R. Wymann, M. Morari, A.M. Zbinden, T. Schnider

vol. AUT00-16

A model based closed loop control system was designed to regulate hypnosis with the volatile anaesthetic Isoflurane. Hypnosis is assessed by means of the Bispectral Index (BIS), a processed parameter derived from the Electroencephalogram (EEG). Isoflurane is administered through a closed-circuit respiratory system. The model for control was identified on a population of 20 healthy volunteers. It consists of three parts: a model for the respiratory system, a pharmacokinetic (PK) and a pharmacodynamic (PD) model to predict BIS at the effect compartment. A cascaded Internal Model Controller (IMC) is employed. The master controller compares the actual BIS and the reference value set by the anaesthetist and provides expired concentration references to the slave controller. The slave controller maneuvers the fresh gas anaesthetic concentration entering the respiratory system. The controller is designed to adapt to different respiratory conditions. Anti-windup measures protect against performance degradation in the event of saturation of the input signal. Fault detection schemes in the controller cope with BIS and expired concentration measurement artifacts. The results of the first pilot study on humans are presented.


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(04)Technical Report

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% Autogenerated BibTeX entry
@TechReport { GenEtal:2000:IFA_104,
    author={A. Gentilini and M. Rossoni and M. Gerosa and C. Frei and R. Wymann and M.
	  Morari and A.M. Zbinden and T. Schnider},
    title={{Modeling and Closed Loop Control of Hypnosis by means of
	  Bispectral Index (BIS) with Isoflurane}},
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