Abstract: AIM: To evaluate the effects of continuous infusion sufentanil during a nitrous oxide-sevoflurane balanced anesthesia in patients undergoing thyroid surgery, and to seek a suitable way to ensure hemodynamic stability and fast recovery for a moderately painful operation.METHODS: 45 patients, ASA physical status I or II with age ranging from 18 to 60 years, scheduled for thyroid surgery with general anesthesia were divided into three groups randomly.Patients were induced with a loading dose of sufentanil 0.15, 0.30, and 0.45 μg/kg, respectively, and continuously infused with sufentanil (0.15, 0.30, 0.45 μg·kg^-1·h^-1) throughout surgery.The sevoflurane concentration was adjusted according to conventional clinical variables, and to keep MAC 1.0-1.3.The sevoflurane vaporizer was weighed before and after anesthesia, and consumption was calculated.MAP and heart rate were recorded at different times (before and after intubation, any intervention, and the time of recovery).Recovery time, postoperative analgesia by VAS, and intraopereative awareness were evaluated.RESULTS: Adequate anesthesia was obtained in all groups.Hypertension was more frequent with the small dose sufentanil, and hypotension requiring treatment was more frequent with the large dose sufentanil. Sevoflurane concentration during surgery decreased significantly with increasing sufentanil as well as the sevoflurane consumption.The 0.45 μg·kg^-1 ·h^-1 sufentanil significantly delayed the return of spontaneous breathing.CONCLUSION: Continuous infusing sufentanil 0.30 μg·kg^-1·h^-1 is optimal to ensure hemodynamic stability, and fast recovery, combined with sevoflurane is suitable for thyroid surgery.

Key words: sufentanil, sevoflurane, thyroid surgery