Supra-axillary Block: A Novel Ultrasound-Guided Supplement to Brachial Plexus Block for Surgery Around Elbow.

Sir,

Subclavian perivascular approach of brachial plexus block is a widely practised regional nerve block for the upper extremity by the anesthesiologists. Despite the successful placement of drug in the supraclavicular region, areas supplied by the intercostobrachial nerve (ICBN, T2) and medial cutaneous nerve of arm (MCNA, C8-T1, T3) get spared, and the patient complains of pain in areas supplied by these nerves. In axilla, ICBN and MCNA are linked together in a plexiform manner. Sometimes, the ICBN is large and gets a twig from the lateral cutaneous branch of the third intercostal nerve (T3). It replaces the MCNA and receives a connection representing the latter from the brachial plexus which is occasionally absent.[1] Studies on cadaver reports 90% incidence of communication between the MCNA and ICBN.[2] This is especially important in surgeries around elbow where the incision site and tourniquet application are usually in these areas which get spared.[3] This necessitates the use of opioids, local infiltration, or conversion to general anesthesia (GA).

Subcutaneous infiltration of local anesthetic (LA) is the current way of managing the mentioned spared areas. But being a blind technique, the infiltration may not give a satisfactory result always. To overcome this, we chose a novel ultrasound-guided nerve block technique, called the “Supraaxillary Block.” The term “supraaxillary” was coined by one of the authors Dr. C. Sekar, who described this block in 2015. This technique will allow a direct visualization of a group of four nerves by ultrasound– ulnar nerve, MCNA, ICBN, and nerve to latissimus dorsi (NLD). A single injection of LA in this area provides an excellent sensory blockade for surgeries around elbow.

Ultrasound-guided supraaxillary block is performed at a higher level in the axillary region where these four nerves ulnar nerve, MCNA, ICBN, and NLD are visualized as a bunch of grapes inferior to the axillary artery (AA). The patient will be lying supine with arm abducted to 110° and elevated above the level of head. The AA is traced towards the apex of axilla by moving the probe medially. As we cross the shoulder joint and enter into the axilla, we will see a bunch of grapes lying inferior to the artery which represents the nerves [Figures 1 and 2]. Since the axilla contains loose areolar tissue, a volume of 12–15 ml of LA is injected in a healthy adult.

Figure 1

Position of ultrasound probe for supra-axillary block

Figure 2

Position of the nerves in relation to axillary artery. S = Superior or cranial, I = Inferior or caudal

After obtaining clearance from Institutional Ethical Committee and review board, a prospective analytical study was conducted on fifty patients (of either sex, age group 18-60 years, American society of anaesthesiologists physical Status I and II) undergoing upper limb surgeries around the elbow. Written informed consent was taken from each patient for participation in the study. All patients received ultrasound-guided supraaxillary block along with subclavian perivascular block. The average time of onset for Supra-axillary block was 8.4 ± 2.8 minutes. Only four patients(8%) required an additional local infiltration due to failure of the block. This could be due to the presence of septae in the area and possible anatomical variations. None of them required GA following the failure of block.

We advocate that, along with subclavian perivascular brachial plexus block, ultrasound-guided single injection of LA in the supraaxillary area will enable the blockade of ICBN and MCNA adequately and will help to achieve excellent surgical conditions for procedures around elbow.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.