I read with great interest the recently published case series conducted by Chan et al. [1] in which the serratus anterior plane (SAP) block was administered for sensory coverage of the intercostobrachial nerve (ICBN) and would like to provide my reflections.

Chan et al. [1] state that they are introducing the “axillary serratus anterior plane (A-SAP) block” and claim it is “novel.” However, this raises several questions. First, administering an SAP block at a higher level (second or third rib) to extend the spread of the injectate to the axilla has already been reported in a cadaveric study conducted by Biswas et al. [2]. In that study, a high-level SAP block was performed at the third rib at the anterior axillary line, while the conventional SAP block is performed at the fifth rib at the midaxillary line. Chan et al. [1] also performed the SAP block at the anterior axillary line at the same level. Second, the needle direction for performing the block was medial-lateral. Although Chan et al. [1] state that their technique is “similar” to that described by Seidel et al., I would argue that it is identical. Importantly, a case report applying this combination of blocks to the same procedure was published in 2020, wherein the SAP block was performed at the second rib at the midaxillary line followed by the supraclavicular brachial plexus block [3]. Therefore, the concept, the plane, the site of the block, the needle direction, and the combination of blocks are identical as those previously described. Thus, Chan et al.’s claims that their block is “superior” and “novel” are unfounded. Applying a new term to a block performed in the same plane, whether in a clinical or cadaveric study, is also inappropriate. Notably, Biswas et al. [2] did not introduce any new terms in their report even though they performed the block at a different site (higher level). Furthermore, applying minor differences to the site but using the same plane or changing the probe position or needle direction is not sufficient to label a technique “novel.” Therefore, introducing the term “A-SAP” block is cumbersome for clinicians, as we already have many confusing nomenclatures for various similar or even identical techniques.

Additionally, administering an infraclavicular brachial plexus rather than a supraclavicular block would be preferable for this type of surgery, as the latter consumes a similar volume of local anesthetic without reliably blocking the ICBN. The infraclavicular block is performed in close proximity to the axilla and thus principally blocks the ICBN, unlike the supraclavicular block. Bigeleisen and Wilson [4] observed that the infraclavicular block covered the ICBN in 77% of those in the medial technique group and 87% of those in the lateral technique group. Notably, the extrathoracic course of the ICBN has considerable anatomical variations [5], which could explain sensory coverage sparing even after an infraclavicular block. In such rare cases, it can be blocked at the axilla itself with a minimal volume of local anesthetic.

Chan et al. [1] also make contradictory statements regarding direct blockage of the ICBN in the axilla. Initially, they state that “The ultrasound-guided ICBN block described by Magazzeni et al. in 2018 showed effective coverage of the upper arm for tourniquet pain” [1]. However, they subsequently state that “Direct identification of the ICBN may be limited by the anatomical variability of the ICBN” [1]. Anatomical variations only play a role in the early stage of the extrathoracic course and have no influence on the direct blockage of the nerve in the axilla. Hence, the former statement is correct, whereas the latter is incorrect and thus contradictory.

To conclude, SAP block performed at a higher level for better axillary coverage has been in clinical practice for a long time. Applying an infraclavicular block can be considered the first choice for creating an arterio-venous fistula in the upper arm. In rare circumstances, the inadequate coverage of ICBN after an infraclavicular block can be managed by directly blocking the ICBN in the axilla. The high-level SAP block can be reserved for cases where the direct blocking of ICBN is not feasible.