A cadaver study of four approaches of ultrasound-guided infraclavicular brachial plexus block.

BACKGROUND AND AIMS: The ultrasound-guided infraclavicular brachial plexus block (USG ICBPB) is a popular technique for forearm surgeries distal to the elbow. Our study details the ultrasound (US) characteristics of this block and the structures encountered by the needle in four approaches to the infraclavicular area - lateral infraclavicular (LICF), costoclavicular medial to lateral (CML) and lateral to medial (CLM) and retroclavicular (R) by anatomical dissection.

METHODS: USG ICBPB was performed in 10 cadavers-5 on the right side and 5 on the left side by each of four approaches and with an 18 gauge Tuohy needle kept in situ , and US characteristics were noted. Anatomical dissection was done and important structures were described in detail.

RESULTS: Needle tip and shaft visibility were least with LICF approach and best in R approach. Needle angle correlated with chest and neck circumference in LICF and CML groups. During dissection, in all approaches, neurovascular structures have been observed in the near vicinity of the needle, especially the thoracoacromial artery (TAA) or its branches. In the R approach, the 'blind spot' behind the clavicle is an area where neurovascular structures were present.

CONCLUSION: The R approach gives better visibility of needle shaft beyond the clavicle, but the clavicle acts as a 'blind-spot' for the US beam obliterating important neurovascular structures. The various neurovascular structures the needle traverses or in its immediate vicinity, do not necessarily make the CML, CLM or R approach any better than the LICF approach.