Objective To explore median effective dose(ED50)of 0.375％ropivacaine based on the cross sectional area(CSA)of supraclavicular brachial plexus block(SCBPB)with L-shaped baffle intervention.Methods Patients scheduled for upper limb surgery from September 2023 to May 2024 at Ningbo NO.6 Hospital were enrolled.Patients were randomly divided into two groups:L-shaped baffle compression group(group L)and non-compression group(group C).CSA of supraclavicular brachial plexus was measured by ultrasound,and 0.375％ropivacaine was administered based on the CSA.The ED50 was determined by using the Dixon up-and-down sequential method,with an initial dose of 0.4 ml/mm2 and an incremental difference of 0.04ml/mm2.If the block was effective within 30 minutes,the next patient received a lower dose;If ineffective,a higher dose was administered.The process continued until seven cross-over points(ineffective to effective)were observed.ED50 and its 95％CI were calculated by using the Probit method.Adverse reactions,such as phrenic nerve paralysis,nerve injury,dyspnea were recorded.Results The ED50 of 0.375％ropivacaine for SCBPB in group C was 0.254 ml/mm2(95％CI:0.228-0.278),while in group L,it was 0.239 ml/mm2(95％CI:0.215-0.262),with no statistically significant difference between two groups(P＞0.05).The incidence of phrenic nerve paralysis in group L was significantly lower than that in group C(14.29％vs.41.67％,P＜0.05).No significant nerve injuries,dyspnea,or local anesthetic toxicity were observed in either group.Conclusion The ED50 of 0.375％ropivacaine for SCBPB with L-shaped baffle compression,based on the CSA of the brachial plexus,was 0.239 ml/mm2(95％CI:0.215-0.262).L-shaped baffle compression significantly reduced the incidence of phrenic nerve paralysis without notable side effects.

Objective To explore median effective dose(ED50)of 0.375％ropivacaine based on the cross sectional area(CSA)of supraclavicular brachial plexus block(SCBPB)with L-shaped baffle intervention.Methods Patients scheduled for upper limb surgery from September 2023 to May 2024 at Ningbo NO.6 Hospital were enrolled.Patients were randomly divided into two groups:L-shaped baffle compression group(group L)and non-compression group(group C).CSA of supraclavicular brachial plexus was measured by ultrasound,and 0.375％ropivacaine was administered based on the CSA.The ED50 was determined by using the Dixon up-and-down sequential method,with an initial dose of 0.4 ml/mm2 and an incremental difference of 0.04ml/mm2.If the block was effective within 30 minutes,the next patient received a lower dose;If ineffective,a higher dose was administered.The process continued until seven cross-over points(ineffective to effective)were observed.ED50 and its 95％CI were calculated by using the Probit method.Adverse reactions,such as phrenic nerve paralysis,nerve injury,dyspnea were recorded.Results The ED50 of 0.375％ropivacaine for SCBPB in group C was 0.254 ml/mm2(95％CI:0.228-0.278),while in group L,it was 0.239 ml/mm2(95％CI:0.215-0.262),with no statistically significant difference between two groups(P＞0.05).The incidence of phrenic nerve paralysis in group L was significantly lower than that in group C(14.29％vs.41.67％,P＜0.05).No significant nerve injuries,dyspnea,or local anesthetic toxicity were observed in either group.Conclusion The ED50 of 0.375％ropivacaine for SCBPB with L-shaped baffle compression,based on the CSA of the brachial plexus,was 0.239 ml/mm2(95％CI:0.215-0.262).L-shaped baffle compression significantly reduced the incidence of phrenic nerve paralysis without notable side effects.