Adaptive bilinear controller for closed circuit anesthesia

Administration of gaseous anesthesia using a closed circuit is cheaper and ecologically safer than the traditional semi-closed circuit. However, gas concentrations are more difficult to control. This paper proposes an adaptive bilinear controller for the automatic control of a closed circuit anesthesia system. Alveolar anesthetic gas concentration, alveolar oxygen concentration and circuit volume are controlled using a liquid anesthetic (Halothane), oxygen and nitrous oxide. Oxygen consumption, nitrous oxide uptake and Halothane uptake are estimated by a least-squares parameter estimator. Derivation of the model used, results from simulations and results from preliminary tests on dogs are presented.