The Impact of Anxiety or Depression on the Sedative Concentration of Propofol

120 consecutive female patients, 18-65 years old, American Society of Anesthesiologists (ASA) physical status I to II, scheduled for hysteroscopic surgery under propofol-based intravenous anesthesia will be recruited in this cohort study. The day before surgery, participants will be assessed the state of preoperative anxiety and depression. On the day of surgery, propofol will be administered by target controlled infusion (TCI) pump. During induction of anesthesia, the level of sedation will be evaluated. The induction dose of propofol, target effect-site concentration(Cet), plasma concentration(Cp) and effect-site concentration (Ce) of propofol will be recorded.