Unconstrained and constrained generalised predictive control of depth of anaesthesia during surgery

Abstract

The unconstrained and constrained versions of generalised predictive control (GPC) are evaluated for on-line administration of anaesthetic drugs during surgery. First, a patient simulator was developed using a physiological model of the patient and the necessary control software was validated via a series of extensive simulation studies. The validated system was then transferred into the operating theatre for a series of clinical evaluation trials. The trials were performed with little involvement of the design engineers and good regulation of the blood pressure has been achieved using fixed-parameter as well the adaptive versions of the algorithm. Following such trials, the design engineer's assessment was that better regulation and control were obtained with the constrained algorithm and the anaesthetist's assessment was that good anaesthesia was achieved, with all patients recovering well after the operations. Furthermore, the constrained algorithm displayed good robustness properties against disturbances such as high stimulus levels and allowed for safe and economically effective administration of the drug isoflurane.