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A New Paradigm for the Closed-Loop Intraoperative Administration of Analgesics in Humans


A. Gentilini, Ch. Schaniel, M. Morari, C. Bieniok, R. Wymann, T. Schnider

vol. AUT01-01

A new paradigm for the closed-loop administration of analgesics during general anesthesia is presented. The manipulated variable in the control system is the infusion rate of the opiate alfentanil, administered intravenously through a Computer Controlled Infusion Pump (CCIP). The outputs to be controlled are the patient's Mean Arterial Pressure (MAP) and the drug concentration in the plasma. Maintaining MAP within appropriate ranges improves the operating conditions for surgical intervention and provides optimal treatment of the patient's reactions to surgical stimuli. Maintaining plasma drug concentrations within ranges specified by the operator enables anesthesiologists to titrate analgesic administration to qualitative clinical end-points of insufficient analgesia. MAP is acquired both invasively and non-invasively through a catheter cannula and a blood pressure cuff, respectively. Since plasma drug concentrations cannot be measured on-line, they are estimated via a Pharmacokinetic (PK) model on the basis of the infusion profile. An explicit Model Predictive Controller (MPC) was designed to achieve the above mentioned objectives. An upper constraint on predicted drug concentrations was imposed to avoid overdosing, whereas constraints on the MAP were introduced to trigger a prompt controller reaction during hypertensive and hypotensive periods. Artifacts in the MAP measurements are rejected to prevent harmful misbehavior of the controller. Finally the results of the clinical validation of the controller on humans are presented and discussed.

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(04)Technical Report

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% Autogenerated BibTeX entry
@TechReport { GenEtal:2001:IFA_13,
    author={A. Gentilini and Ch. Schaniel and M. Morari and C. Bieniok and R.
	  Wymann and T. Schnider},
    title={{A New Paradigm for the Closed-Loop Intraoperative
	  Administration of Analgesics in Humans}},
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