Physiological Modelling and Fuzzy Control of Anaesthesia via Vaporisation of Isoflurane by Liquid Infusion

Abstract: The paper reports on the development and simulation of a physiological model relating to Depth of Anaesthesia via Mean Arterial Pressure (MAP) measurements using the anaesthetic drug isoflurane. Isoflurane is an anaesthetic gas normally administered through a vaporiser-based system which was widely reported to be unreliable and unsuitable for precision driving. Hence, in this study we propose a new technique which allows such anaesthetic to be administered first as a liquid solution which is later vaporised as it is passed through a heating chamber; such effect being included in the overall model structure. Moreover, the development and application of a fuzzy constrained Single Input Single Output (SISO) version of the popular Generalised Predictive Control (GPC) algorithm, which uses the Quadratic programming (QP) approach, is presented; Mean Arterial pressure (MAP) is used as an inferential variable to indicate the level of unconsciousness. Simulation experiments showed that excellent regulation of blood pressure around set-point targets is achieved.