Robust internal model control for depth of anaesthesia

This paper investigates the depth of anaesthesia control problem during a surgery, where paralytic, analgesic and hypnotic are regulated by means of monitored administration of specific drugs. A robust internal model controller (RIMC) based on the Bispectral Index (BIS) is proposed. The controller compares the measured BIS with its input reference to provide the expected propofol concentration, and then the controller manipulates the anaesthetic propofol concentration entering the anaesthetic system to achieve the desired BIS value. This study develops patient dose-response models and provides an adequate drug administration regimen to avoid under or over dosing of patients. Numerical simulations illustrate that the RIMC performed better than the traditional PID controller. The robust performance of the two controllers is evaluated for a wide range of patient models by varying in patient parameters. The other relative performance is also compared for different BIS step settings.