Median effective dose of ropivacaine for spinal anesthesia when combined with sufentanil in patients undergoing caesarean section / 中华麻醉学杂志

ABSTRACT

Objective To determine the median effective dose (ED50 ) of ropivacaine for spinal anesthesia when combined with sufentanil in patients undergoing caesarean section. Methods Twenty-eight ASA Ⅰ or Ⅱ parturients, aged 18-40 yr, weighing 50-110 kg, undergoing cesarean section under combined spinal-epidural anesthesia, were enrolled in this study. Combined spinal-epidural anesthesia was performed at L2,3 interspace. The mixture of ropivacaine and 5 fig sufentanil was injected into the subarachnoid space over 30 s. The initial dose of ropivacaine was 11 mg. The dose was increased/decreased by 1 mg in the next patient. The ED50 and 95% confidence interval were calculated by up-and-down method. Results The ED50 of ropivacaine was 7.780 mg (95% confidence interval 6.850-8.836 mg). Conclusion When combined with sufentanil 5 μg, the ED50 of ropivacaine for spinal anesthesia is 7.780 mg in patients undergoing caesarean section.