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Selective trunk block (SeTB): a simple alternative to hybrid brachial plexus block techniques for proximal humeral fracture surgery during the COVID-19 pandemic
  1. Ranjith Kumar Sivakumar,
  2. Pornpatra Areeruk and
  3. Manoj Kumar Karmakar
  1. Department of Anaesthesia and Intensive Care, Chinese University of Hong Kong, Faculty of Medicine, Shatin, New Territories, Hong Kong
  1. Correspondence to Professor Manoj Kumar Karmakar, Department of Anesthesia and Intensive Care, The Chinese University of Hong Kong, Shatin, Hong Kong; karmakar{at}

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To the Editor

We read with interest the letter titled “Proximal humeral fracture surgery in the COVID-19 pandemic: advocacy for regional anesthesia” by Tognù and colleagues in the May issue of RAPM.1 We commend Tognù and colleagues for their efforts and congratulate them for sharing with us their experience of using regional anesthesia for proximal humeral fracture (PHF) surgery during the current pandemic. We are in agreement with Tognù and colleagues for using a combined (hybrid) interscalene and supraclavicular brachial plexus block (BPB) for PHF surgery but would like to share with your readers our preliminary experience of using an alternative BPB technique for PHF surgery. We refer to this technique as “selective trunk block (SeTB)” and is based on the principle that majority of the innervation to the upper extremity, including the shoulder, arise from the three trunks (superior, middle and inferior) of the brachial plexus. Targeted injection of the individual trunks, using small volumes of local anesthetic, produces anesthesia of the entire upper extremity (C5-T1) except for the area innervated by the intercostobrachial nerve (T2). SeTB is made possible from being able to accurately identify the individual trunks of the brachial plexus using ultrasound (figure 1C,F).2 The SeTB is performed as a “two-injection” peri-plexus technique with the first injection targeting the superior (figure 1D) and middle (figure 1E) trunk at the interscalene groove, and the second injection targeting the inferior trunk at the corner pocket of the supraclavicular fossa (figure 1F). We use up to a maximum of 25 mL of a 1:1 mixture of lidocaine 2% with 1:200 000 epinephrine and levobupivacaine 0.5% for the block. Complete sensorimotor blockade of the entire upper extremity, except for the medial aspect of the upper arm (T2), usually develops within 15–20 min of the injection. We have successfully used SeTB, in conjunction with intravenous sedation (dexmedetomidine 0.1–0.4 mcg/kg/hour), for several patients requiring PHF surgery recently.

Figure 1

A sequence of transverse oblique sonograms acquired during the selective trunk block. The anterior (*) and posterior (+) tubercles of the transverse processes are highlighted in the sonograms and the block needle is represented using white arrow heads. (A) The C7 VR is seen lying anterior to the C7 TP and lateral to the VA, (B) the C6 VR is seen emerging between the two tubercles of the C6 TP, (C) the C5 and C6 ventral rami are seen fusing to form the ST. Note the ST, MT and C8 VR are stacked up together with the C8 VR lying on top of the T1 TP-first rib complex in this sonogram, (D) LA injection with the needle tip positioned next to the ST, (E) LA injection with the needle tip positioned next to the MT, (F) needle tip at the corner pocket with LA injection next to the IT. CA, carotid artery; IT, inferior trunk; LA, local anesthetic; MT, middle trunk; OMH, omohyoid muscle; SA, scalenus anterior; ScA, subclavian artery; SCM, sternocleidomastoid; SM, scalenus medius; SSN, suprascapular nerve; ST, superior trunk; STa, anterior division of ST; STp, posterior division of ST; VA, vertebral artery; VR, ventral ramus.

SeTB may offer advantages over the hybrid BPB techniques. First, it is accomplished using relatively smaller volumes of local anesthetic (25 mL) than that typically used for a hybrid BPB (30–50 mL).1 3–5 We are confident further reduction in local anesthetic volume can be achieved with SeTB and future dose finding studies are warranted. Second, while ipsilateral phrenic nerve palsy is a well-known side effect of interscalene BPB, SeTB may be phrenic nerve sparing like a superior trunk block6 because the injection is performed at a distance (more caudal) from the phrenic nerve. Third, since SeTB anesthetizes the entire upper extremity, we have also found it useful as the sole anesthetic for managing patients presenting for intramedullary nailing of pathological fracture of the humerus and internal fixation of combined fractures of the proximal humerus and elbow or hand. While these are encouraging results, future research to establish the safety and efficacy of the SeTB technique is warranted. We believe SeTB has the potential to become the “one size fits all” or “all-purpose” technique for upper extremity surgery. We thank Tognù and colleagues for their contribution and hope this communication will draw attention to SeTB as a simple alternative to the many hybrid BPB techniques currently described for proximal humeral surgery.



  • Twitter @Ranjith_SRK

  • Contributors RKS was involved with preparation of manuscript and editing the figure. PA was involved with editing the figure and reviewing the manuscript. MKK was involved with editing manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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