Purpose: This study aimed to find a quick and timely way to investigate the individual variation of efficacy of opioid analgesic in Chinese patients undergoing elective surgeries. Methods: 120 female patients receiving elective surgery under general anesthesia were recruited into this study. At the time of routine intravenous anesthetic induction we observe the efficacy of opioid analgesic including analgesic effect, effects on Narco-trend index, sedative effect, effects on respiratory system, and aslo effects on cardiovascular system.

Patients with the following diseases were excluded: known history of chronic pain, psychiatric diseases or communication disorders, diabetes mellitus, severe cardiovascular diseases, kidney or liver diseases with poor hepatic function, alcohol or drug abuse, heavy smoker, pregnancy or at the lactation period.

Inclusion Criteria:

• Aged 20-65 years
• Anesthesiologists (ASA) physical status I or II;
• Within ±20% of ideal body weight;
• Agreed to participate the research

Exclusion Criteria:

• History of chronic pain;
• Psychiatric diseases;
• Diabetes mellitus;
• Severe cardiovascular diseases;
• Kidney or liver diseases;
• Alcohol or drug abuse (according to the criteria of DSM-IV);
• Pregnancy or at lactation period;
• Disagree to participate to the research

120 Chinese female patients receiving elective surgery under general anesthesia

Because 3 patients couldn't maintain the SPO2 at 90% and 1 patient was at deep sedation, 4 subject patients were not analysed in the final results. These patients were performed as a routine intravenous anesthetic induction.