Median effective dose of 0.5% ropivacaine for ultrasound-guided femoral nerve block: dose per unit femoral nerve cross-sectional area
10.3760/cma.j.cn131073.20210228.00622
- VernacularTitle:超声引导0.5%罗哌卡因股神经阻滞的半数有效剂量：单位股神经横截面积剂量
- Author:
Hao GUO
1
;
Shuzhen YU
;
Ueda KENICHI
;
Wenhui GAO
;
Weiwei ZHANG
;
Jing LI
;
Yongzhuang HAO
;
Guifei WANG
;
Jianfeng WEI
;
Jinfeng ZHANG
;
Tiane LUO
Author Information
1. 山西省人民医院麻醉科，太原 030012
- Keywords:
Amides;
Femoral nerve;
Nerve block;
Dose-response relationship, drug;
Ultrasonography
- From:
Chinese Journal of Anesthesiology
2021;41(6):731-734
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To determine the median effective dose (ED 50) of 0.5% ropivacaine based on femoral nerve cross-sectional area for ultrasound-guided femoral nerve block. Methods:Patients of both sexes, aged 18-64 yr, of American Society of Anesthesiologists physical status I or Ⅱ, with body mass index of 20-30 kg/m 2, scheduled for elective open reduction and internal fixation for patella fracture or removal of patella fracture by internal fixation, were enrolled in this study.Ultrasonic localization of femoral nerve was performed for measurement of the femoral nerve cross-sectional area, and 0.5% ropivacaine was injected based on the area.ED 50 was determined by Dixon′s up-and-down sequential method.The initial dose was 0.22 ml/mm 2, and the difference between the two successive doses was 0.02 ml/mm 2.The effective block was defined as complete loss of pain sensation in the areas of anterior skin of knee joint, skin on the inner side of the calf and dorsal medial skin of the foot and the degree of motor block was in stages 1-3 assessed using Brunnstrom motor function within 30 min after nerve block.Nerve block was considered ineffective if pain occurred in any nerve distribution area mentioned above.The study was terminated if 7 effective and ineffective alternating waves occurred.ED 50 and 95% confidence interval (CI) were calculated using Probit analysis. Results:Twenty-seven patients were enrolled in the study with the femoral nerve cross-sectional area (75±5) mm 2.ED 50 (95%CI) of 0.5% ropivacaine for ultrasound-guided femoral nerve block was 0.106 (0.069-0.125) ml/mm 2. Conclusion:ED 50 of 0.5% ropivacaine based on femoral nerve cross-sectional area for ultrasound-guided femoral nerve block is 0.106 ml/mm 2.
