Dexamethasone or Dexmedetomidine as Local Anesthetic Adjuvants for Ultrasound-guided Axillary Brachial Plexus Blocks with Nerve Stimulation

BACKGROUND The purpose of this study was to evaluate the effect of dexamethasone or dexmedetomidine added to ropivacaine on the onset and duration of ultrasound-guided axillary brachial plexus blocks (BPB). METHODS Fifty-one ASA physical status I-II patients with elective forearm and hand surgery under axillary brachial plexus blocks were randomly allocated to receive 20 ml of 0.5% ropivacaine with 2 ml of isotonic saline (C group, n = 17), 20 ml of 0.5% ropivacaine with 2 ml (10 mg) of dexamethasone (D group, n = 17) or 20 ml of 0.5% ropivacaine with 2 ml (100 µg) of dexmedetomidine (DM group, n = 17). A nerve stimulation technique with ultrasound was used in all patients. The onset time and duration of sensory blocks were assessed. RESULTS The duration of the sensory block was extended in group D and group DX compared with group C (P < 0.05), but there was no significant difference between group D and group DX. However, there were no significant differences in onset time in all three groups. CONCLUSIONS Dexamethasone 10 mg and dexmedetomidine 100 µg were equally effective in extending the duration of ropivacaine in ultrasound-guided axillary BPB with nerve stimulation. However, neither drug has significantly effects the onset time.