Fig. 6. Dose–response curves of the isoflurane effect site concentration  versus all Bispectral Index® (BIS®;  A ) or all Narcotrend® index data (  B ). The isoflurane effects site concentrations were calculated with a k^e0value of 0.16 for BIS® data and of 0.18 for Narcotrend® data. The concentration-  versus -response relation was calculated from the mean values of the pharmacokinetic–pharmacodynamic parameters of all patients.