Comparison between perivascular and perineural ultrasound-guided axillary brachial plexus block using...

Ultrasound (US)-guided regional blocks are becoming increasingly popular as its use increases success rate, shortens block onset time and reduces complications. Currently, there exist two methods to perform US-guided axillary brachial plexus block (US-ABPB), the perivascular (PV) and the perineural (PN) techniques. We compared the two techniques to study the block characteristics and other variables using levobupivacaine.

In this prospective, randomised trial, 60 patients were randomly allocated to receive a PV (n = 30) or PN (n = 30) US-ABPB. The local anaesthetic agent, 0.5% levobupivacaine and total volume of 36 ml of solution were identical in all the subjects. For both the groups, the musculocutaneous nerve was first located and then anaesthetised with 6 ml. Subsequently in the PV group, 30 ml was deposited dorsal to the axillary artery (6 o'clock position). In PN group, the median, ulnar and radial nerves were individually anaesthetised with volumes of 10 ml each. The onset and duration of sensory block, the onset and duration of motor block, number of failed blocks and complications were noted.

No difference was observed between the two groups in terms of success rate (PV - 93.33%, PN - 96.66%), sensory onset (PN: 8.07 (standard deviation [SD] ± 0.651) min and PV: 8.14 [SD ± 1.079] min; P = 0.754), motor onset (PN: 14.62 [SD ± 2.077] min and PV: 14.93 [SD ± 1.844] min; P = 0.557) and total duration of anaesthesia. No complications were observed in both groups.

The PV technique provides a simple alternative for PN US-ABPB. In the light of emerging needling positions for PV and PN techniques, this study calls for large scale trials and much research in this area before one defines best or safe approach. PV technique may be considered as an alternative method for US-ABPB in patients with anatomical variation or difficulties in identifying the individual nerves.