A PID-based Structure for MISO Approach to Anaesthesia Control Problem

This work introduces a control architecture based on Proportional-Integral-Derivative (PID) controller addressing drugs co-administration in the total intravenous anaesthesia process. The control problem focuses on a multiple-input -single-output nonlinear process, where the infusion rates of propofol and remifentanil are the control variables and the Bispectral Index Scale (BIS) is the controlled variable. The analyzed structure exploits an external predictor of the patient state that converts the control problem to the linear case. The interaction between the used drugs is handled by a reference converter element through continuous re-computation of the setpoint. The proposed control system is evaluated by exploiting a set of virtual patients that are representative of a wide population. The scenario considers induction and maintenance phases, as both of them are important from a practical point of view. The obtained results show that the PID controller in combination with the external predictor is able to meet all the clinical requirements, which is confirmed through the analysis of process specific performance indexes.