A study on endpoint of motor response in interscalene brachial plexus block in adults

Objective To study the feasibility of pectoralis major,deltoid motor response as the endpoint in interscalene brachial plexus block(ISBPB)guided by peripheral nerve stimulator(PNS)in adults.Methods Two hundred and forty adult patients scheduled for upper limbs surgery under ISBPB guided by PNS were randomly divided into 4 groups of endpoint of pectoralis major motor response(A),of deltoid motor response(B),of biceps motor response(C)and of pectoralis major,deltoid or biceps motor response(D)with 25 cases each.Threshold current of stimulation,time to acquirement of endpoint,time to onset of motor block,time to onset of sensory block of nerve branches,effect of motor block,effect of sensory block of nerve branches and comprehensive effect of nerve block were compared among the four groups.Results The time to acquirement of endpoint of group D was less than that of group A,B and C(P0.05),threshold current of stimulation,time to onset of motor block,time to onset of sensory block of nerve branches,effect of motor block,effect of sensory block of nerve branches and comprehensive effect of nerve block had no statistical difference among the four groups.The excellent and good rate of nerve block was 90.8%.Conclusion Endpoint of pectoralis major,deltoid motor response were satisfactory and safe indication for an accurate needle placement during interscalene brachial plexus block guided by PNS in adults.