Fig. 1. Timing of data collection. (Top ) Patients investigated without surgical stimulation. Anesthesia was induced with 2 mg/kg propofol. Thereafter, a 45-min waiting period was allowed for the effects of propofol to dissipate and for transition to pure desflurane anesthesia. The concentration–response curves were obtained before skin incision. (Bottom ) Patients investigated during surgical stimulation. Again, after induction of anesthesia, a 45-min waiting period was allowed for the effects of propofol to dissipate and for transition to pure desflurane anesthesia. The concentration–response curves were obtained during gynecologic laparotomies between opening and closure of the peritoneum.