Effects Of Two Ways Of Injecting Dexmedetomidine On Intermuscular Brachial Plexus Block Under BIS Monitoring

Objective We aimed to compare the effects of peripheral nerve injection and intravenous injection dexmedetomidine on interscalene brachial plexus block and BIS,and evaluate its effectiveness and safety.Methods 90 patients scheduled for shoulder surgery were randomly divided into 3 groups,interscalene brachial plexus block was performed under ultrasound guidance.Group DP(n=30)was performed with dexmedetomidine(0.5?g /kg)+ 0.375% ropivacaine mixture 20 ml.Group DIV(n=30)and group R(n=30)were performed with 0.375% ropivacaine 20 ml.After block,group DIV was administered intrabenously with 20 ml dexmedetomidine(0.5 ?g/kg).Group DP and group R were administered intrabenously with 20 ml isotonic sodium chloride.Onset time of sensory and motor block,duration of block,analgesic time were recorded.HR,MAP,SpO2,BIS were recorded every 10 min from before the brachial plexus block(T0)to 60 min after block(T1~T6)and complications were also recorded.Results No significant difference was found in the onset time of motor and sensory block in 3 groups(P>0.05).The duration of block and analgesia time in group DP were longer than in group DIV and group R(P<0.05),the analgesia time in group DIV was longer in group R(P<0.05).BIS,HR,MAP in group DP were less than group R at T2~T6(P<0.05).BIS,HR,MAP in group DIV were less than group R at T1~T6(P<0.05).BIS,HR,MAP in group DIV were less than group DP at T1~T3(P<0.05).Compared with previous time point,BIS,HR,MAP were less in group DP at T2~T4(P<0.05),and less in group DIV at T1,T2(P<0.05).2 patients(6.7%)in group DP occurred bradycardia,less than group DIV(16.7%)but higher than group R(0%).Conclusions Peripheral nerve injection and intravenous injection of dexmedetomidine 0.5?g/kg can prolong the analgesia time of brachial plexus block,stable hemodynamics,decrease BIS,provide good sedation,but may lead to bradycardia.Compared with intravenous injection,peripheral nerve injection of dexmedetomidine has longer analgesic time,slower sedative effect,lower incidence of bradycardia,and does not cause nerve damage,which can be safely applied to brachial plexus nerve block.