Pre-injection technique to identify neural elements in the costoclavicular space for brachial plexus block: Where and what to inject?

Abstract

Sir, We read with interest the captioned letter “Use of a pre-injection technique to identify neural elements in the costoclavicular space for brachial plexus block for upper limb orthopaedic surgery”.[1] We appreciate the authors’ idea of a pre-injection technique to identify the neural elements in the costoclavicular space (CCS), but have few suggestions. The authors have chosen the supraclavicular fossa as their pre-injection site and administered 3 ml of local anaesthetic (LA) with the assumption that it would reach the CCS. However, one should keep in mind that even a small LA volume of 5 ml at the supraclavicular fossa may be associated with hemidiaphragmatic paralysis (HDP).[2] Therefore, we rather recommend a hydro-dissection technique using 0.9% saline at the CCS. In this method, as the needle passes the subclavius muscle and approaches the brachial plexus sheath (paraneural sheath),[3] small aliquots of 1-2 ml of 0.9% saline will be injected [Figure 1a] to appreciate if the injection is intramuscular or just outside the epimysium of the subclavius muscle/paraneural sheath. Once confirmed, the block needle is gently advanced into the paraneural sheath between the lateral and posterior cords [Figure 1b] and a second injection of saline will now separate the tightly clustered cords. This helps to delineate the neural components.Figure 1: (a) Schematic diagram demonstrating hydro-dissection technique with needle tip just outside the subclavius muscle and the brachial plexus sheath at the costoclavicular space (CCS); (b) Schematic diagram demonstrating block needle inside the brachial plexus sheath at the gap/fissure between the lateral and posterior cord of the brachial plexus sheath at the CCS. AA: Axillary artery (1st part); AV: Axillary vein; LC: Lateral cord; MC: Medial cord; PC: Posterior cord; Blue coloured arrows demonstrating the brachial plexus or paraneural sheath around the cords of the brachial plexus at the CCS. Black star (*) demonstrating the gap/fissure between the lateral and posterior cord of the brachial plexus after the saline hydro-dissection techniqueThis hydro-dissection technique is simple, effective, carries no additional risks for HDP and does not require two separate injections. Hence, we recommend it over the pre-injection technique described by the authors at the supraclavicular fossa for identifying the neural elements in the CCS. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.