The Optimal Dosage of Ropivacaine for Arthroscopic Knee Surgery

According to previous clinical experience, 0.5% ropivacaine was given in the subarachnoid cavity, and the initial dose was set at 2.5 mL (12.5mg). Dixon's up-and down method was adopted to adjust or down-adjust the dose of ropivacaine in the next patient according to the experimental results of the previous patient, and the adjusted dose was 0.1 mL (0.5mg).