Fig. 4. (A ) Median Cortical Input (CI) versus target remifentanil (CeREMI) and propofol (CePROP) concentrations. Mesh represents the linearly interpolated surface through data (filled circles ). Interquartile (25th–75th percentile) ranges of target propofol concentration for a given Observer's Assessment of Alertness/Sedation (OAA/S) level and remifentanil level are shown as shaded (OAA/S 5 =light gray , OAA/S 0 =dark gray ) patches on the interpolated surface. Median values correspond to the respective solid white line . This surface together with the shaded interquartile ranges indicates that for a fixed OAA/S level and target propofol concentration, CI decreases with increasing CeREMI. (B ) Median root mean square (RMS) electroencephalogram amplitude versus CeREMIand CePROP. All other details as for A .