Adaptive Control of Depth of Anesthesia using a Fractional Order Gradient Based Adaptation Mechanism

In this paper, a model reference adaptive controller (MRAC) with an RST control structure is employed to control the depth of the anesthesia. The polynomial coefficients of the RST controller are adjusted according to a fractional order normalized gradient based adaptation mechanism. The propofol infusion rate and the Bispectral Index (BIS) are considered as the system input and output, respectively. The propofol distribution in the patient model is described with a Pharmacokinetic-Pharmacodynamic (PK-PD) model. The PK-PD model parameters depend on physical specifications of the patient including age, weight, and gender. The proposed MRAC is employed to reach the desired BIS in the presence of disturbance and the measurement noise for different patients. Simulation results have demonstrated the effectiveness of the proposed method.