研究单位：[1]Department of Anaesthesiology,Tongji Hospital of Tongji Medical College,Huazhong University of Science and Technology,Wuhan,Hubei 430030,P.R.China
研究目的：
This study aims to determine the minimum effective dose of bupivacaine 0.5% in 90% of patients undergoing lower limb surgery with ultrasound-guided spinal anesthesia using Taylor's approach. A biased coin design up-and-down sequential method is applied. The initial dose is 15 mg of bupivacaine 0.5%. After 45 successful spinal anesthesia, the ED90 of bupivacaine 0.5% will be calculated.
