Fig. 3. The Bispectral Index (BIS) versus  time in case 3. Time 0–5 min displays the last 5 min (i.e. , the time after blood-effect site equilibration) of the 15-min period, when only propofol was given by a target-controlled infusion with a target concentration of 1 μg/ml. At time 5 min, midazolam was added at 0.035 mg/kg in 1 min followed by a continuous infusion of midazolam of 0.035 mg · kg⁻¹· h⁻¹for 59 min. At time 65 min, the midazolam infusion was terminated, but the target-controlled infusion of propofol was still continued. The area considered to be associated with adequate hypnosis for surgery (BIS, 40–60) is shown within the grid lines. The volunteer was responsive to verbal command and/or mild prodding at all times.