Determination of the Median Effective Concentration of Ropivacaine for Sensory-Motor Separation in Ultrasound-Guided Superior Trunk Brachial Plexus Block
REN Li
LI Dongqing
XU Bo
WANG Liping
CHEN Yongjun
Abstract：Objective This study aimed to determine the median effective concentration(EC50)of ropivacaine for sensory-motor separation in ultrasound-guided brachial plexus block at the superior trunk level.Methods This study included 41 patients scheduled to undergo elective shoulder arthroscopy at Zhuhai People's Hospital from March to May 2025.All patients received an ultrasound-guided superior trunk brachial plexus block using 10 mL of ropivacaine at a starting concentration of 0.3%.The drug concentration was adjusted using the up-down sequential method with a step size of 0.05%.Sensory and motor functions were assessed 30 minutes after block administration:combined sensory and motor blockade was considered a negative response(21 cases),whereas sensory blockade without motor blockade was defined as a positive response(20 cases).The EC50 of ropivacaine for sensory-motor separation and its 95%confidence interval(CI)were calculated using a Probit regression model.Results Among the 41 patients undergoing shoulder arthroscopy,20 showed a positive response and 21 showed a negative response.The EC50 of ropivacaine for sensory-motor separation in ultrasound-guided brachial plexus block at the superior trunk was 0.232%(95%CI:0.212%-0.252%),and the EC90 was 0.286%(95%CI:0.262%-0.358%).Conclusion The EC50 of 10 mL ropivacaine for sensory-motor separation in ultrasound-guided brachial plexus block at the superior trunk is 0.232%.It is recommended to use 1.3 to 1.5 times the EC50 for superior trunk brachial plexus block in clinical anesthesia.
Keywords：ropivacainemedian effective concentrationsuperior trunk brachial plexus block
Publication Date：2025-10-20
Online Publishing Date：2025-10-28(First online date of this platform, not the publication date of the document)
Pages：6( 156-161 )