Quantifying additive uncertainty in an identified multivariable model for closed loop control of depth of anesthesia*

General anaesthesia is characterized by unconsciousness through the action of hypnotics, and by loss of the ability to perceive pain through the action of analgesics. Because most hypnotic drugs (i.e. Propofol) have no pain relieving properties, they are used together with analgesic drugs (i.e. Remifentanil). In this paper, we perform a robustness analysis against interval uncertainty in the model parameters for closed-loop anesthesia control. These uncertainties are taken from the model parameters of 9 patients in response to Propofol and Remifentanil drug infusions. Based on this data, we develop a method to determine the effect of the additive uncertainties on the stability and robustness of the closed-loop. The response of the Bispectral index has been then tested in simulation on 24 mimicked patient models, showing good performance.