Comparison of ultrasound and nerve stimulation techniques for brachial plexus block for regional hemodynamic changes of upper extremity

OBJECTIVE: To compare ultrasound guidance versus nerve stimulator guidance supraclavicular brachial plexus block for regional hemodynamic changes of upper extremity. METHODS: Sixty ASA I-II patients scheduled for upper extremity operation were randomly assigned to receive a supraclavicular brachial plexus block guided by either ultrasound (U group, n = 30) or nerve stimulation (N group, n = 30).20 ml mixture of equal volumes of 2% lidocaine and 0.75% ropivacaine was injected in both groups. Regional hemodynamic parameters were measured in the ipsilateral ulnar artery and radial artery, using pulsed-wave Doppler ultrasound, before and 30 minutes after the block. Regional hemodynamic parameters included peak systolic velocity (PSV), end-diastolic velocity (EDV), time averaged maximum velocity (TAMAX), resistance index (RI), pulsatility index (PI), cross-sectional area (Area) and Blood flow (Q). The intensity of sensory block was measured at 30 minutes after the block. RESULTS: There was no significant difference in the hemodynamic parameters of ulnar artery and radial artery before the block between two groups. Compared with N group, EDV, TAMAX and Q of ulnar artery were higher in U group (1.88-fold, 1.71-fold and 1.84-fold)(P < 0.01 or P < 0.05), PI and RI of ulnar artery were lower in U group (P < 0.01) at 30 minutes after the block, EDV of radial artery was higher in U group (1.47-fold) (P < 0.01), PI and RI of radial artery were lower in U group (P < 0.05) at 30 minutes after the block. Comparing the hemodynamic parameters of ulnar artery and radial artery with complete block between two groups at 30 minutes after the block, EDV, TAMAX and Q of ulnar artery in U group were higher than that in N group (1.68-fold, 1.55-fold and 1.62-fold) (P < 0.01 or P < 0.05), PI of ulnar artery in U group was lower than that in N group (P < 0.01), EDV and TAMAX of radial artery in U group was higher than that in N group (1.54-fold and 1.26-fold) (P < 0.01 or P < 0.05), PI and RI of radial artery in U group was lower than that in N group (P < 0.05). The rate of complete block in U group was higher than that in N group (28/30 vs 22/30, P < 0.05). CONCLUSION: Ultrasound-guided supraclavicular brachial plexus block enhance the degree of sympathetic block of upper extremity, especially of ulnar artery and increase the blood flow of ulnar artery compared with nerve stimulator.