Comparison of the Motor and Sensory Block by Ropivacaine and Bupivacaine in Combination with Lidocaine in Interscalene Block

Introduction: The effects of ropivacaine and bupivacaine in interscalene block havebeen studied, but we usually combine lidocaine with ropivacaine or bupivacaineto fasten the onset. However, the effects of these combinations are not studied.Purpose: To compare the effects of two different concentrations of the combinationof ropivacaine or bupivacaine with lidocaine. Materials and Methods: Onehundred adult patients scheduled for repair of fracture of the upper extremity underinterscalene block were randomly allocated into one of the groups receiving thecombination of 15 mL of ropivacaine 0.375% (Ropivacaine 0.375 group), ropivacaine0.75 % (Ropivacaine 0.75 group), bupivacaine 0.25 % (Bupivacaine 0.25 group), orbupivacaine 0.5 % (Bupivacaine 0.5 group) with lidocaine 1.0 % 15 mL. The onsetand duration of motor and sensory blocks were compared among the 4 groups byKruskal Wallis test followed by Mann-Whitney U test. Results: Three patients in theRopivacaine 0.375 group did not show any motor blocks. Ropivacaine groups hadsignificantly slower onset of motor block and longer duration of motor and sensoryblocks than Bupivacaine groups. Bupivacaine 0.5 group had significantly longer durationof both blocks than Bupivacaine 0.25 group, while Ropivacaine 0.375 and 0.75groups had the similar duration of both blocks. Conclusions: In interscalene blockcombined with lidocaine, ropivacaine had slower onset of motor block and longerduration of both blocks than bupivacaine. Only bupivacaine showed the differentduration of the blocks between two concentrations.