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Abstract
Background Inconsistent nomenclature and anatomical descriptions of regional anesthetic techniques hinder scientific communication and engender confusion; this in turn has implications for research, education and clinical implementation of regional anesthesia. Having produced standardized nomenclature for abdominal wall, paraspinal and chest wall regional anesthetic techniques, we aimed to similarly do so for upper and lower limb peripheral nerve blocks.
Methods We performed a three-round Delphi international consensus study to generate standardized names and anatomical descriptions of upper and lower limb regional anesthetic techniques. A long list of names and anatomical description of blocks of upper and lower extremities was produced by the members of the steering committee. Subsequently, two rounds of anonymized voting and commenting were followed by a third virtual round table to secure consensus for items that remained outstanding after the first and second rounds. As with previous methodology, strong consensus was defined as ≥75% agreement and weak consensus as 50%–74% agreement.
Results A total of 94, 91 and 65 collaborators participated in the first, second and third rounds, respectively. We achieved strong consensus for 38 names and 33 anatomical descriptions, and weak consensus for five anatomical descriptions. We agreed on a template for naming peripheral nerve blocks based on the name of the nerve and the anatomical location of the blockade and identified several areas for future research.
Conclusions We achieved consensus on nomenclature and anatomical descriptions of regional anesthetic techniques for upper and lower limb nerve blocks, and recommend using this framework in clinical and academic practice. This should improve research, teaching and learning of regional anesthesia to eventually improve patient care.
- analgesia
- Anesthesia, Local
- REGIONAL ANESTHESIA
- Brachial Plexus
- Lower Extremity
Data availability statement
Data are available in a public, open access repository. Not applicable.
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WHAT IS ALREADY KNOWN ON THIS TOPIC
Names and anatomical descriptions for regional anesthetic techniques are sometimes inconsistent. This inconsistency can be an impediment to understanding of the literature, collaboration in research, and applying research into clinical practice and education.
WHAT THIS STUDY ADDS
Having produced standardized nomenclature for abdominal wall, paraspinal and chest wall regional anesthetic techniques, we aimed to similarly do so for upper and lower limb peripheral nerve blocks.
HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY
The results of this study are a huge step closer to standardizing names and anatomical description of regional anesthesia techniques, which will have an impact on research, education, and clinical practice.
Background
Upper and lower limb peripheral nerve blocks have been widely used to provide anesthesia and analgesia for a range of surgical procedures. The advent of ultrasound-guidance with improved sonoanatomical understanding has enabled clinicians and researchers to refine regional anesthetic approaches and develop novel ones. While this has likely led to improvements in patient care, the natural tendency to apply a different label to each new variation, to distinguish it from previous iterations, has led to an unwieldy expansion of the nomenclature in regional anesthesia techniques. This contributes to inconsistent communication in clinical and academic settings, which not only undermines teaching and training in regional anesthesia and related disciplines, but may also hamper interpretation and synthesis of clinical research. As a consequence, this may have implications for safe adoption of these techniques and patient access to regional anesthesia.1
Thus, there is a need to standardize nomenclature of regional anesthetic techniques for the benefit of trainees, researchers, clinicians, and patients. This has been successfully performed for abdominal, paraspinal, and chest wall blocks,2 with evidence that the results may have been adopted and increasingly implemented.3–6 However, there remains no consensus on nomenclature for upper and lower limb regional anesthetic techniques.
Therefore, we conducted an international Delphi study aiming to achieve consensus on nomenclature for upper and lower limb nerve blocks. These recommendations regarding names and definitions are intended to have broad applications in regional anesthesia clinical practice, education, and scholarly work in the future.
Methods
Six representatives from the American Society of Regional Anesthesia and Pain Medicine and European Society of Regional Anesthesia and Pain Therapy formed the Executive Committee for the study (KE-B, NME, EA, ERM, MW, and SK). The steering committee included a member of the executive committee in addition to three other members selected based on their track record of academic output content expertize in upper and lower limb nerve blocks (JG, APerlas, and AT). A panel of international experts were invited as collaborators, based on previously published criteria,2 to participate.
We replicated a methodology used in a previous study, which is reported in detail elsewhere,2 and reported in detail in online supplemental appendix 1. In brief, a modified three-round Delphi approach was used, with two rounds of electronic questionnaires and a third round-table discussion round.
Supplemental material
Scope
We aimed to achieve consensus on two characteristics of common upper and lower limb peripheral nerve blocks: names by which they are referred to, and anatomical descriptions for the position of the needle-tip during injection for each of these regional anesthetic techniques. Names were defined as the word or set of words by which each technique is known, addressed, or referred to. Anatomical descriptions were defined by the anatomical location of the needle-tip. This meant that non-ultrasound-guided methods of needle-tip localization were not considered (eg, landmark-based techniques). The type of needle used, needle trajectory, patient position, the position of the ultrasound transducer, use of catheters, or any other technical elements related to the performance of regional anesthetic techniques were not considered unless there was a fundamental requirement for doing so (eg, two techniques with identical needle-tip position but significantly different needle trajectories). Similarly, efficacy, safety, feasibility, surgical anesthesia, or any other clinical element of each regional anesthetic technique were not considered. For the purposes of this study, we defined upper limb nerve blocks as any regional anesthetic technique aiming to provide anesthesia or analgesia to any area of the neck, clavicle, shoulder, arm, wrist, hand and fingers. We defined lower limb nerve blocks as any regional anesthetic technique aiming to provide anesthesia or analgesia to any area of the hip, thigh, knee, leg, ankle and foot. Techniques that have already been addressed in a previous study were not included here.2
Long-list formulation
Following a qualitative literature review, the steering committee produced a long list of regional anesthetic techniques of the upper and lower limb. This included variations in names or anatomical descriptions of different approaches. All regional anesthetic techniques were collated in a Microsoft Excel (Microsoft, Redmond, Washington, USA) spreadsheet that was then reviewed by all members of the Steering Committee to refine, clarify and reference. Techniques were excluded if they were unclear, duplicates, or outside the scope of the current project. Given potential areas of uncertainty, clarifying questions (eg, “Should blocks of a plexus have the word “plexus” in the name?”) were asked to facilitate decision-making by the steering committee in each round.
First round
As per previously described methodology,2 the long-list of all names, anatomical descriptions and clarifying questions was electronically distributed to all collaborators, who were invited to “agree”, “disagree” or be “unsure” for each. Each name could be voted on independent of the anatomical description and vice versa, and uncertainty was accepted. Collaborators were also invited to anonymously make free text written comments on each term and clarifying question. These anonymized responses were analyzed and revised by the steering committee aiming to increase the potential for consensus in the second round (figure 1).
(A) Flow chart demonstrating Steering Committee decision-making for names between Delphi rounds to achieve consensus. (B) Flow chart demonstrating steering committee decision-making for anatomical descriptions between Delphi rounds to achieve consensus.
Steering committee members used all the information gathered from voting and answers for clarifying questions to generate a revised list of names and/or descriptions with justification for the changes implemented.
Second round
Anonymized results and proposed changes were shared with all collaborators who participated in the first round. Methodology mirrored the first round, both for collaborator voting and result handling (figure 1), with further clarifying questions asked. In this round, a proposal was made to produce a template for naming and describing individual peripheral nerve blocks that are uncommonly performed, associated with multiple approaches, or did not achieve consensus in naming or describing. In this round, it also became clear that needle approaches (insertion site and trajectory) may have a role in distinguishing different techniques in specific block approaches (eg, retroclavicular vs infraclavicular brachial plexus block), and thus a decision was made by the executive committee to consider including needle approaches within the scope of this nomenclature project. While this was a deviation from our previous methodology, it was warranted given the nature of some peripheral nerve blocks.
Third round
Collaborators who completed the first two rounds were invited to participate in a virtual round table discussion aiming to achieve consensus for names, anatomical descriptions, and clarifying questions, using videoconferencing software (Zoom Video Communications, San Jose, California, USA) that allowed live polling. The session was chaired by one member of the executive committee (KE-B).
Statistical analysis
We used a convenience sample of 94 collaborators, which is greater than most Delphi studies2 7 and adds to the strength of our results. Data were reported descriptively. When percentages are reported, they refer to the proportion of collaborators that agreed with the inclusion of a proposed name or anatomical description, unless otherwise stated (ie, stating “50%” means “50% agreement for inclusion without further modification”). All denominators for percentages reported were based on responses, rather than the number of collaborators.
Results
A total of 105 experts were invited to be collaborators; 94 (90%) agreed to participate. Of those who agreed, the number of collaborators participated in the first, second, and third rounds were 94, 91, and 65 respectively (online supplemental appendix 2). Details on all proposed names, anatomical descriptions, clarifying questions and changes made in each round are shown in online supplemental appendix 2.
Supplemental material
First round
In the first round, 104 blocks (44 upper limb blocks; 60 lower limb blocks) and 4 clarifying questions were proposed. For upper limb blocks, 12 names and 1 anatomical description achieved strong consensus and proceeded to the second round unchanged. There was no consensus on 17 names and 18 anatomical descriptions. Several approaches to the infraclavicular brachial plexus had low consensus, with a suggestion to harmonize and simplify the terminology of these blocks based on anatomical location.
For lower limb blocks, there was strong consensus for 25 names and 25 anatomical descriptions, and no consensus on 17 names and 15 anatomical descriptions. There was strong consensus for the name and anatomical description of the adductor canal block (85% and 80%, respectively).
For the clarifying questions, there was agreement that blocks targeting a nerve plexus should have the word “plexus” in the name (88%), and that blocks targeting an individual nerve should have the word “nerve” in the name (81%). Collaborators were asked whether the nomenclature for blocks of a peripheral nerve should include the anatomical location of the injection point: (a) after the name of the nerve in brackets (42%); (b) after the name of the nerve in full (17%); (c) before the name of the nerve (36%); (d) did not need to be included 4%); (e) or some other unspecified option (1%). Finally, given concerns that it may be required for this particular project, Collaborators were asked whether blocks with different needle trajectories should be named separately, and 51% said yes.
Second round
A total of 24 upper limb and 24 lower limb nerve blocks were considered, and two clarifying questions. For upper limb nerve blocks, 13 names and 6 anatomical descriptions had strong consensus. There was a proposal to provide a template for naming peripheral nerve blocks, as three approaches in this round (mid-humeral block, forearm block, and wrist block) were deemed insufficiently precise. The remainder proceeded for discussion in the third round.
Sixteen lower limb names and 11 anatomical descriptions had strong consensus and were included in the final list of agreed on nomenclature, with 1 name (posterior tibial nerve block, 26%) and 1 anatomical description excluded (description for the fascial iliaca block (suprainguinal approach), 33%). The remainder proceeded for discussion in the third round.
One of the clarifying questions proposed a template for names of each individual peripheral nerve block: <NAME OF NERVE>block at the<LOCATION>, which had weak consensus (64%). The second clarifying question asked whether this Delphi study should aim to achieve consensus for names and anatomical descriptions of every individual peripheral nerve block, which had no consensus (42%). However, taking both clarifying questions, comments suggested proposing a naming template was a more practical solution than naming every individual nerve block. This template could be applied to individual peripheral nerve blocks that are uncommonly performed, associated with multiple approaches, or did not achieve consensus in naming or describing. Therefore, individual peripheral nerve blocks that were considered at any stage in this study and met one of these criteria were agreed to follow this template (online supplemental appendix 3).
Supplemental material
Third round
Three upper limb names and seven anatomical descriptions were discussed. Strong consensus was achieved for all three names and five anatomical descriptions, and weak consensus for two anatomical descriptions. Notably, there was strong agreement to harmonize names of infraclavicular brachial plexus blocks based on the anatomical location of injection, with the term ‘infraclavicular brachial plexus block’ representing a group of three approaches. Weak consensus was achieved for the anatomical descriptions of the infraclavicular brachial plexus block (retroclavicular approach) (72%) and the axillary brachial plexus block (66%).
For lower limb nerve blocks, 2 names and 10 anatomical descriptions were discussed. There was strong consensus for both names and seven anatomical descriptions, but weak consensus for three anatomical descriptions. The pericapsular nerve group block had 63% agreement with the anatomical description, while the inferior medial (67%) and inferior lateral (69%) genicular nerve blocks also had weak consensus. Final results can be seen in tables 1 and 2.
Consensus achieved for upper limb block names and anatomical descriptions
Consensus achieved for lower limb block names and anatomical descriptions
Discussion
Upper and lower limb peripheral nerve blocks have been adopted as ultrasound-guided techniques since the introduction of ultrasound into regional anesthesia practice. Many of these blocks are considered traditional approaches with established names and anatomical descriptions. However, both traditional and contemporary regional anesthetic techniques have historically had little consensus on the names and/or anatomical descriptions. In this modified Delphi study, 69 collaborators achieved strong consensus on 38 names and 33 anatomical descriptions for upper and lower limb regional anesthetic techniques and weak consensus for 5 anatomical descriptions. The consensus we achieved should clarify nomenclature for approaches that we anticipated to be controversial (eg, adductor canal block and femoral triangle block), required multiple rounds of revision and revised methods (eg, infraclavicular brachial plexus block approaches, fascia iliaca block, sciatic nerve block), and those that required further anatomical interpretation (eg, genicular nerves blocks). Finally, we also defined and obtained consensus on a recommended template for naming peripheral nerve blocks.
Proximal lower limb blocks were most frequently found to have inconsistency in nomenclature. The adductor canal block has been widely adopted over the past 15 years as an alternative for femoral nerve block to provide postoperative analgesia to the anteromedial aspect of the knee while avoiding significant quadriceps weakness.8 9 Similarly to what happens with other fascial plane blocks, there has been some controversy on the nomenclature and exact location of the adductor canal.10 Early descriptions were based on surface landmarks and advocated an approach in the ‘mid-thigh’.11 However, ultrasound imaging has provided some clarity to the nomenclature as it is possible to consistently identify the upper and lower limits of the adductor canal in the thigh (figure 2).12 The upper limit of the adductor canal is the apex of the femoral triangle, the point where the medial border of the sartorius muscle crosses the medial border of the adductor longus muscle. The inferior border of the adductor canal is the adductor hiatus, an opening in the aponeurotic distal attachment of the adductor magnus muscle on the femur through which the superficial femoral vessels cross toward the popliteal fossa, and can be identified on ultrasound as the area where the superficial femoral vessels ‘dive’ deep toward the popliteal fossa, moving away from the sartorius muscle.12 In the current study, we achieved consensus by defining adductor canal blocks as an injection at the compartment that contains the femoral vessels distal to the apex of the femoral triangle and proximal to the adductor hiatus. An injection performed in the aponeurotic compartment proximal to the apex of the femoral triangle is, by definition, a femoral triangle block. Although the anatomical definition of the adductor canal block was expected to be controversial, it achieved strong consensus on the name (85%) and anatomical description (80%) in the first round, and the femoral triangle block name (76%) and anatomical description (76%) in the second. However, there was no consensus on further defining proximal and distal femoral triangle blocks.
Lower limb ultrasound anatomy at three levels: mid-femoral triangle (location of femoral triangle block), apex of the femoral triangle, and through the adductor canal (location of adductor canal block). ASRA, American Society of Regional Anesthesia.
Another area that this study successfully addressed was the nomenclature of different approaches to similar neural structures. There was consensus that the approach should be added after the block name and listed in parentheses. For example, we adopted this methodology in naming various infraclavicular brachial plexus block approaches. Moreover, the difference between approaches should be rooted in anatomical concepts: a retroclavicular approach is where the needle is inserted cephalad to the clavicle; a costoclavicular approach is where the final position of the needle tip is located adjacent to the cords of the brachial plexus around the first part of the axillary artery; and the coracoid approach is where the final position of the needle tip is located adjacent to the cords around the second part of the axillary artery (figure 3). Describing the needle trajectory explicitly, or its position relative to the subclavian artery is intuitive and relevant as different approaches to the block may land the needle adjacent to the cords in different parts of the infraclavicular fossa and be associated with non-identical risks based on each trajectory.
Three approaches to the infraclavicular brachial plexus block relative to the first, second and third parts (proximal, deep to, and distal to the pectoralis minor muscle, respectively) of the axillary artery. ASRA, American Society of Regional Anesthesia.
The only other nerve block approaches in which the needle trajectory or its position was applied were the fascia iliaca and sciatic nerve. The different approaches to the sciatic nerve block included: transgluteal, infragluteal, and anterior approaches. In the second round of voting, the name subgluteal nerve block was harmonized with the transgluteal approach. The rationale behind choosing the transgluteal approach was to avoid confusing the subgluteal and infragluteal descriptors. Transgluteal infers the needle going through the gluteal muscle, while the infragluteal infers needle insertion with a trajectory toward to the sciatic nerve target inferior to the lower border of the gluteal muscles.
For the genicular nerves blocks, there was a strong consensus on the names of the different blocks based on their anatomical locations: superior medial (81%), superior lateral (80%), inferior medial (78%), and inferior lateral (81%). However, the anatomical description of the inferior medial and inferior lateral genicular nerves blocks achieved only weak consensus (67% and 69%, respectively). Some authors consider the inferior genicular nerve as a group of nerves rather than one nerve with multiple vessels that may represent the genicular vessels. Whether single or multiple, it was agreed that the anatomical description should include the proximity to the genicular artery.
One of the key agreements achieved was to name peripheral nerve blocks based on a template that includes the name of the nerve and the anatomical location at which it is blocked (figure 4). Blocks in which no consensus was achieved followed the proposed template of naming the block using the name of the nerve and the anatomical area where the block was performed (figure 4). Moving forward, this template can therefore be used for any individual peripheral nerve block.
Template for naming peripheral nerve blocks.
The other clarifying question that was included in the first round of voting was whether to include the word ‘plexus’ in the block name. This promotes clarity, which is obvious when we discuss axillary nerve blocks versus axillary brachial plexus blocks or the supraclavicular nerve block versus the supraclavicular brachial plexus block (figure 5).
Schematic representation of the various brachial plexus block approaches along its anatomical course. ASRA, American Society of Regional Anesthesia.
There are limitations to this study, many of which are related to Delphi methodology.13 First, this method of generating consensus does not handle large differences in opinion well, and whatever differences there are might not be sufficiently investigated. Second, there remains a risk that the views of the steering committee may influence the analysis and not all collaborators participated in the third round of voting. However, the steering committee was divided into different workgroups and reviewed all the comments submitted during each round to ensure all Collaborators' opinions were considered. Third, although there is reporting guidance,13 14 there are no clear methodological guidelines for the use of the Delphi method in the harmonization of nomenclature, nor evidence of reliability. However, we adhered to the same methodology adopted in the first part of the project, which has evidence of successful implementation.2 Delphi methodology has been used to achieve consensus and generate guidelines in other settings.15–17
In conclusion, we achieved consensus for nomenclature in upper and lower limb regional anesthetic techniques and established principles for standardization of terminology moving forward. Clinicians, educators, and researchers are encouraged to adhere to this universal standard of names and anatomical descriptions when researching, teaching or performing regional anesthesia of the upper and lower limbs.
Data availability statement
Data are available in a public, open access repository. Not applicable.
Ethics statements
Patient consent for publication
Ethics approval
This study received IRB exemption from Stanford University (ID 58535).
Acknowledgments
This project was supported and approved by both ASRA Pain Medicine and ESRA boards. Administrative support for the project was provided by ASRA Pain Medicine. The authors would like to thank Ms Jennifer Gantry for her artistic work included in this manuscript.
Supplementary materials
Supplementary Data
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Footnotes
X @elboghdadly, @DrEAlbrecht, @EMARIANOMD, @PerlasAnahi, @SerkanTulgarMD, @sanjibadhikary, @baakaltparmak1, @nigeb444, @bowness_james, @CarvalB, @kijinnchin, @AlwinChuan, @Steve_Coppens, @kaohesham, @MonicaHarbellMD, @rosie_hogg, @HoltzMaggie, @rljohnsonmd, @MKwesiKwofie, @claralexlobo, @ajrmacfarlane, @colinjmccartney, @gamcleod2, @sgmemtsoudis, @PeterMerjavy, @LouiseMoran75, @AhtshamNiazi, @amit_pawa, @DrPhilipPeng, @BridgetPulos, @ESchwenkMD, @mariapsebastian, @ESoffin, @DrRayTang, @LloydTurbitt, @Ropivacaine, @KVermeylen, @nelkassabany
Contributors Study conception and design: KE-B, EA, NME, SK, ERM and MW. Study conduct: KE-B, EA, JG, NME, SK, ERM, AT, AS and APerlas. Data analysis: KE-B, NME and AS. Manuscript preparation: KE-B, NME. Manuscript revision: KE-B, EA, JG, NME, SK, ERM, AT, AS and APawa. Manuscript approval: all authors. Guarantors: NE, KE, EA, AP, ERM, SK, AT, JG.
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 EA: grants from Swiss Academy for Anesthesia Research, Bbraun, Swiss National Science Foundation. Honoraria from Bbraun and Sintetica. JG: consulting fees from Pacira Biosciences and Pajunk Medical. AP: honoraria from FuijiFilm Sonosite. MW: advisory Board for Sintetica, Honoraria from Wisonic and Medovate. SA: Advisory Panel for DATAR innovations. JA: moderator of the Working Group Regional Anaesthesia Switzerland, Honoraria from Medtronic and Sintetica. AMRA: honoraria form AllerganSébastien Bloc—Consulting fees from BBraun—GE Medical Systems—Pajunk—Pfizer SAS. JB: Consulting fees from Intelligent Ultrasound. BC: jonoraria from Bbraun and Rivanna, Consulting from Stryker and Flat Medical, Research funding from Pacira, Share Options from Flat Medical. AC: speaking honoraria from GE Healthcare, royalties from textbook Oxford University Press. SC: consulting fees from MSD, Bbraun Medical, Wisonic, research grants from BARA (Belgian association of Regional anesthesia), ESRA and BeSARP (Belgian anesthesia society) HE-Consulting/Advisory Board Neuronoff, SPR, GateScience, NeuronoffBenjamin Fox—Speaking fees from Medovate and Sintetica. SG: consulting and speaking fees from MSD Switzerland. PH: royalties from Bestek Products. NH: Honoraria from Butterfly Network. RMGH- Honoraria from GE Healthcare. MH: consulting fees from Pacira Biosciences, Honoraria from Parcira Biosciences and Pajunk Medical. BMI: research funding to institution from SPR Therapeutics, Infutronix, Epimed International. AM: Consultant fees from Intelligent Ultrasound. CM: consultant fees from Masimo Corporation. SGM: Owner SGM Consulting, Partner Parvizi Surgical Innovations, Patent for Multicatheter infusion system. AN: Research support from SPR Therapeutics. SLO: Royalties from book Wolters-Kluwer. APawa: Honoraria from GE Healthcare, Consulting fees from Pacira Biosciences. PP: equipment support from Sonosiite Fujifilm Canada. MPS: Medovate speaking but no honoraria paid. SKS- Cofounder of Gate Science (developing a catheter for performing nerve blocks) JS: consulting fees from Sintetica. RT: Consulting fees from Clarius Mobile Health. VU: Associate Editor of the Canadian Journal of Anesthesia and Regional Anesthesia & Pain Medicine journals. TV: honoraria from CSL Behring, Pajunk.
Provenance and peer review Not commissioned; externally peer reviewed.
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