Abstract: AIM : To study the minimal effective dose of sufentanil spinal anesthesia in cesarean section.METHODS: Forty patients undergoing cesarean section were enrolled in this study and L3/4 was chosen for lumbar puncture.The solution used for spinal anesthesia was sufentanil and bupivacaine, in which the dose of bupivacaine was fixed 7.5 mg. While the initial dose of sufentanil was 1.2 μg, according to 1.2 times increase or decrease the administration. If the level of spinal anesthesia reached to T6 and up to 1 hour, the dose decreased 1 grade for next patient. On the contrary, the dose increased 1 grade in the next one. The ED₅₀ of sufentanil was calculated by Dixon-Massey sequential method.RESULTS:Twenty-one patients had the good effect of spinal anesthesia. The ED₅₀ of sufentanil for cesarean section was 0.84 μg, and its 95% confidence interval was 0.78-0.90 μg.CONCLUSION: The minimal effective dose of sufentanil combined with bupivacaine 7.5 mg for spinal anesthesia in cesarean section was 0.84 μg.

Key words: sufentail, bupivacaine, anesthesia, spinal, dose-response relationship, sequential