A data processing device is provided for an anesthesia device for feeding an intravenously administered hypnotic, a volatile hypnotic, and an opioid such that the volume flow can be adjusted. The device determines and standardizes the effective concentrations of the anesthetics. A pharmacokinetic model adds up the standardized concentrations of the hypnotics to a total hypnotic concentration. An isobole is calculated based on a coordinate plane with a total hypnotic concentration axis and an opioid concentration axis, as a function of the currently determined concentrations. The system displays a two-dimensional action diagram with the y-axis as an indicator of the total hypnotic concentration and the x-axis as an indicator of the standardized opioid concentration. The calculated standardized total hypnotic concentration and opioid concentration and the isoboles determined are displayed. The display is adapted to changes occurring in the isoboles determined in the course of time.
