Knowledge of pharmacodynamic interaction of opioids, volatile and intravenous anesthetics is a prerequisite for rational drug dosing in general anesthesia. Whereas dosing of volatile anesthetics according to MAC (ETAG rules) provides a similar safety to prevent awareness an recall as using EEG monitoring, a similar concept is not available for propofol anesthesia. We are working on interaction models using laryngoscopy and verbal/tactile stimulation instead of skin incision to extend the MAC concept by integrating opioids and propofol. Recently developed interaction models are used to visualize the potency of a given drug combination in anesthesia display systems and may help the practitioner to optimize the combination of hypnotics and opioids in general anesthesia. We currently validate interaction models and investigate clinical utility of Smart Pilot View ™(Dräger Medical, Lübeck, Germany). Our research is performed in cooperation with the Department of Anesthesia at Groningen University Medical Center, Netherlands, Prof. MMRF Struys.