Annals of Biomedical Engineering

, Volume 15, Issue 1, pp 19–34 | Cite as

Automatic control of anesthesia using two feedback variables

  • George F. Schils
  • Frank J. Sasse
  • Vincent C. Rideout
Article

Abstract

A new controller of anON/OFF type was implemented for halothane anesthesia. A proportional-plus-integral controller with time-delay compensation proved not to be robust enough for the known clinical situation, as shown both in computer simulations and in animal trials. TheON/OFF controller proved to be less sensitive to parameter mismatches, and repeated animal trials showed a short response time and acceptable steady-state tracking. A method for switching the controlled effect of the drug was also developed, since anesthetic agents have multiple effects. Mean arterial blood pressure and a measure ofEEG frequency were chosen as controlled variables, both being depressed by halothane. A coordinator forces the system state as near the desired values of these variables as possible, given that only one drug is used.

Keywords

Servo-anesthesia Halothane Multivariable control ON/OFF control Drug controllers Drug delivery systems 

Nomenclature

A/D

analog-to-digital

CO2

carbon dioxide

CSA

electroencephalographic compressed spectral array display

D/A

digital-to-analog

ECG

electrocardiogram

EEG

electroencephalogram

MAC

minimal alveolar concentration

MAP

mean arterial blood pressure

PI

proportional-plus-integral controller

SEF

electroencephalographic spectral edge frequency

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Copyright information

© Pergamon Journals Ltd. 1987

Authors and Affiliations

  • George F. Schils
    • 1
  • Frank J. Sasse
    • 2
  • Vincent C. Rideout
    • 3
  1. 1.Sandia National LaboratoriesLivermore
  2. 2.Department of AnesthesiologyUniversity of WisconsinMadisonWisconsin
  3. 3.Department of Electrical and Computer EngineeringUniversity of WisconsinWisconsin

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