The Minimum Local Anesthetic Concentration Of Ropivacaine In Patient Receiving Infraclavicular Brachial Plexus Block

Objective:This study was aimed to study the minimum local anesthetic concentration of ropivacaine in patient receiving infraclavicular brachial plexus block,under which concentration the anaesthesiologist can provide effective anaesthesia with minimal motor block without local anesthetic systemic toxicity and neurotoxicity to the maximun extent.It is better for surgeon to find nerve injury during the operation and to evaluate the effect after the operation.Methods:40 patients scheduled for surgical procedures below elbow were enrolled in this trial. All patients, ASA physical status classⅠ～Ⅱ, aged between 18 and 65 yr received an infraclavicular brachial plexus block by nerve stimulator. The total volume was 60ml,the concentration started at 0.25% and increased or decreased at intervals of 0.01%, depending on the response of the previous patient, using the technique of up-down sequential allocation. Minimum local anesthetic concentration and 95% confidence interval was obtained by probit analysis. Results:The EC50 and 95% CI for ropivacaine was 0.176% and (0.116%-0.212%)Conclusions:The minimum local anesthetic concentration of ropivacaine in patient receiving infraclavicular brachial plexus block was 0.176%.The effective concentration of ropivacaine can provide effective anaesthesia with minimal motor block.