Block performance indices of perivascular and perineural techniques of ultrasound-guided axillary block in upper limb surgeries: A comparative study

Background: Nerve block anesthesia is a common regional anesthesia used for upper limb surgeries because of its ability to target the operative site and provision of impressive postanesthetic pain relief. This randomized, single-blinded study compared the quality of block of the perineural (PN) and perivascular (PV) techniques of axillary brachial plexus block under ultrasound guidance. Methods: Sixty-six participants were recruited into either PV or PN groups. The local anesthetic (LA) comprised 14 ml of 0.5% bupivacaine, 14 ml of 1% lidocaine, and 2 ml of dexmedetomidine (50 mu g/ml). Under ultrasound guidance, 6 ml of LA was deposited around the musculocutaneous nerve for both groups. For the PV group, 24 ml was deposited dorsal to the axillary artery while 8 ml each was deposited around median, radial, and ulnar nerves for the PN group. Results: The mean total procedure time in PN group was significantly longer than in the PV group (7.82 +/- 0.95 min vs. 4.79 +/- 1.11 min; P = 0.001). Participants in the PN group required more needle passes (66.7% required 4 passes while 81.8% required only 2 passes in the PV group). The success rate was 100% in PN group and 93.9% in PV group (P = 0.49). Conclusion: The PV and PN techniques were comparable in terms of their success rates and total anesthesia-related times. The PN technique had higher success rate and faster block onset, but the PV provided a quicker performance time and fewer needle passes. Hence, PV technique may be preferable to PN for high-volume surgical units.