The potencies for motor block after intrathecal ropivacaine and bupivacaine

VernacularTitle:蛛网膜下腔注射罗哌卡因与布比卡因运动神经阻滞效力的比较
Author: Tao ZHANG ; Jianwei CHEN ; Kangqing XU ; Wenqi HUANG ; Xiaodan WU
Publication Type:Journal Article
Keywords: Anesthesia,spinal; Anesthetics,local; Motor block
From: Chinese Journal of Anesthesiology 2011;31(2):214-216
CountryChina
Language:Chinese
Abstract: Objective To determine the median effective doae (ED50) for motor block after intrathecal ropivacaine and bupivacaine. Methods Sixty ASA Ⅰ or Ⅱ patients, aged 18-64, weighing 46-75 kg, undergoing elective urological surgery under combined spinal-epidural anesthesia, were randomized into 2 groups ( n = 30each) receiving intrathecal 0.5% ropivacaine and 0.5% bupivacaine respectively. The ED50 was determined by up-down sequential allocation. The initial dose was 4 mg. Each time the dose increased/decreased by 1 mg. Efficacy was determined by the occurrence of any motor block in either lower extremity (modified Bromage scale > 0)within 5 or 10 min after the spinal injection. Results The intrathecal ED50 for motor block was 6.68 mg for ropivacaine (95% confidence interval 6.27-7.13 mg) and 4.07 mg for bupivacaine (95% confidence interval 3.56-4.47mg) . The relative motor blocking potency ratio was ropivacaine/bupivacaine 0.61. Conclusion The potency of intrathecal ropivacaine is lower than that of bupivacaine for motor block.