Estimating the time-delay for predictive control in general anesthesia

Monitoring and controlling the depth of general anesthesia is very important since over-dosing and under-dosing can be dangerous for the well-being of the patient. One of the devices used to monitor the depth of anesthesia is the BIS (Bispectral Index) monitor. The relation between the BIS signal, measured by the BIS monitor, and the effect of the administered drugs is given by a function called Hill curve. The aim of this contribution is to implement a procedure for i) the estimation of the time-delay introduced by the computational effort employed by the BIS monitor and ii) the estimation of the parameters of a linear Hill curve. The estimation algorithm is implemented based on the cross-correlation analysis (CCA) between a real BIS signal and a simulated BIS signal. Initially, the algorithm was validated using only simulated signals, followed by a clinical study. The estimated time-delay will be used further in the prediction model of the Extended Prediction Self-Adaptive Control (EPSAC) algorithm.