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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., Competing Interests: 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., (© American Society of Regional Anesthesia & Pain Medicine 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Objectives: This dose-finding study aimed to determine the minimum effective volume in 90% of patients (MEV90) of lidocaine 1.5% with epinephrine 5 μg/mL for ultrasound-guided costoclavicular block., Methods: Using an in-plane technique and a lateral-to-medial direction, the block needle was positioned in the middle of the 3 cords of the brachial plexus in the costoclavicular space. The entire volume of lidocaine was deposited in this location. Dose assignment was carried out using a biased-coin-design up-and-down sequential method, where the total volume of local anesthetic administered to each patient depended on the response of the previous one. In case of failure, the next subject received a higher volume (defined as the previous volume with an increment of 2.5 mL). If the previous patient had a successful block, the next subject was randomized to a lower volume (defined as the previous volume with a decrement of 2.5 mL), with a probability of b = 0.11, or the same volume, with a probability of 1 - b = 0.89. Success was defined, at 30 minutes, as a minimal score of 14 of 16 points using a sensorimotor composite scale. Patients undergoing surgery of the elbow, forearm, wrist, or hand were prospectively enrolled until 45 successful blocks were obtained. This clinical trial was registered with ClinicalTrials.gov (ID NCT02932670)., Results: Fifty-seven patients were included in the study. Using isotonic regression and bootstrap confidence interval, the MEV90 for ultrasound-guided costoclavicular block was estimated to be 34.0 mL (95% confidence interval, 33.4-34.4 mL). All patients with a minimal composite score of 14 points at 30 minutes achieved surgical anesthesia intraoperatively., Conclusions: For ultrasound-guided costoclavicular block, the MEV90 of lidocaine 1.5% with epinephrine 5 μg/mL is 34 mL. Further dose-finding studies are required for other concentrations of lidocaine, other local anesthetic agents, and multiple-injection techniques.

Background and Objectives: This multicenter, randomized trial compared intravenous (IV) and perineural (PN) dexamethasone for ultrasound (US)-guided infraclavicular brachial plexus block. Our research hypothesis was both modalities would result in similar durations of motor block., Methods: One hundred fifty patients undergoing upper limb surgery with US-guided infraclavicular block were randomly allocated to receive IV or PN dexamethasone (5 mg). The local anesthetic agent (35 mL of lidocaine 1%-bupivacaine 0.25% with epinephrine 5 μg/mL) was identical in all subjects. Patients and operators were blinded to the nature of IV and PN injectates. During the performance of the block, the performance time, number of needle passes, procedural pain, and complications (vascular puncture, paresthesia) were recorded.Subsequently, a blinded observer assessed the success rate (defined as a minimal sensorimotor composite score of 14 of 16 points at 30 minutes), onset time as well as the incidence of surgical anesthesia (defined as the ability to complete surgery without local infiltration, supplemental blocks, IV opioids, or general anesthesia). Postoperatively (at 24 hours), the blinded observer contacted patients with successful blocks to enquire about the duration of motor block, sensory block, and postoperative analgesia. The main outcome variable was the duration of motor block., Results: No intergroup differences were observed in terms of technical execution (performance time/number of needle passes/procedural pain/complications), onset time, success rate, and surgical anesthesia. However, compared to its IV counterpart, PN dexamethasone provided 19% to 22% longer durations for motor block (15.7 ± 6.2 vs 12.9 ± 5.5 hours; P = 0.009), sensory block (16.8 ± 4.4 vs 13.9 ± 5.4 hours; P = 0.002), and postoperative analgesia (22.1 ± 8.5 vs 18.6 ± 6.7 hours; P = 0.014)., Conclusions: Compared with its IV counterpart, PN dexamethasone (5 mg) provides a longer duration of motor block, sensory block, and postoperative analgesia for US-guided infraclavicular block. Future dose-finding studies are required to elucidate the optimal dose of dexamethasone.

Background and Objectives: The optimal site for local anesthetic injection during an ultrasound-guided supraclavicular brachial plexus block (BPB) is not known. We tested the hypothesis that local anesthetic injected deep to the "brachial plexus sheath" during supraclavicular BPB would produce faster onset of surgical anesthesia than an injection superficial to the sheath., Methods: After research ethics approval and informed consent, 32 patients undergoing upper-extremity surgery under an ultrasound-guided supraclavicular BPB were randomly assigned to receive 25 mL of a 1:1 mixture of 2% lidocaine with 1:200,000 epinephrine and 0.5% bupivacaine, deep to (subfascial, Gp SF) or superficial to (extrafascial, Gp EF) the brachial plexus sheath. Sensory-motor blockade of the ipsilateral musculocutaneous, median, radial, and ulnar nerves and time to "readiness for surgery" (defined as a sensory and motor block scale of 1 in all the 4 nerves tested) were assessed by a blinded observer, using a 3-point qualitative scale (2 to 0), every 5 minutes for 40 minutes and at 2, 4, 6, 8, 10, 12, and 24 hours after surgery., Results: The time to "readiness for surgery" was significantly shorter (Gp SF: 7 ± 3 minutes vs Gp EF: 20 ± 10 minutes; P < 0.001), and the duration of postoperative analgesia was longer (Gp SF: 9.3 ± 1.4 hours vs Gp EF: 6.1 ± 1.4 hours; P < 0.001) in the subfascial group than in the extrafascial group. There were no complications directly related to the technique or the local anesthetic injection., Conclusions: Injection of local anesthetic deep to the brachial plexus sheath at the supraclavicular fossa, under ultrasound-guidance, results in faster onset of surgical anesthesia and prolonged duration of postoperative analgesia than an injection superficial to the sheath.

Background: This prospective, randomized, observer-blinded study compared double-, triple-, and quadruple-injection ultrasound (US)-guided axillary brachial plexus block (AXB) for upper-extremity surgery., Methods: One hundred twenty patients were randomly allocated to receive a double- (n = 40), triple- (n = 40), or quadruple-injection (n = 40) US-guided AXB. The local anesthetic agent (lidocaine 1.5% with epinephrine 5 μg/mL) and total volume (35 mL) were identical in all subjects. For all 3 groups, the musculocutaneous nerve was identified and anesthetized first. Subsequently, a perivascular technique was performed. Lidocaine was deposited at the 6-o'clock position of the axillary artery for the 2-injection group. For the 3- and 4-injection groups, injections were carried out at the 12-/6-o'clock and 2-/10-/6-o'clock positions, respectively. During the performance of the block, the performance time, number of needle passes, and complications (vascular puncture, paresthesia) were recorded. Subsequently, a blinded observer assessed the onset time, block-related pain scores, and success rate (surgical anesthesia). The main outcome variable was the total anesthesia-related time (sum of performance and onset times)., Results: No differences were observed among the 3 groups in terms of total anesthesia-related time (29.2-31.4 mins), success rate (90.0%-97.5%), block-related pain scores, vascular puncture, and paresthesia. Compared with its 3- and 4-injection counterparts, the double-injection technique required fewer needle passes (4.0 ± 1.6 vs 5.2-6.0 ± 1.7-2.8; both P ≤ 0.001)., Conclusions: Double-, triple-, and quadruple-injection US-guided perivascular AXB result in comparable success rates and total anesthesia-related times. Because it requires fewer needle passes, the double-injection technique provides a simple alternative for US-guided AXB.

Background and Objectives: One of the advantages of ultrasound-guided peripheral nerve block is that visualization of local anesthetic spread allows for a reduction in dose. However, little is known about the effect of dose reduction on sensory and motor block duration. The purpose of the present study was to compare the duration of sensory and motor axillary brachial plexus block (ABPB) with 15 or 40 mL mepivacaine 1.5%., Methods: Thirty patients were randomly allocated to receive ultrasound-guided ABPB with either 15 (group 15 mL, n = 15) or 40 mL (group 40 mL, n = 15) mepivacaine 1.5%. Onset, efficacy, and duration of sensory and motor block were compared., Results: Two patients in group 15 mL needed an additional rescue block before surgery and were excluded from subsequent analysis. The overall median duration of sensory and motor block was significantly shorter in group 15 mL (225 [148-265] mins vs 271 [210-401] mins and 217 [144-250] mins vs 269 [210-401] mins, respectively; P < 0.01). Duration of sensory and motor block of individual nerves was significantly shorter in group 15 mL (20%-40% reduction for sensory and 18%-37% for motor block). Time to first request of postoperative analgesia was also significantly reduced in group 15 mL (163 [SD, 39] vs 235 [SD, 59] mins, respectively, P < 0.05). There were no differences in the other block characteristics., Conclusions: In ABPB with mepivacaine 1.5%, reducing the dose from 40 mL to 15 mL (62.5%) shortens the overall duration of sensory and motor block by approximately 17% to 19%, reduces sensory and motor block duration of individual nerves by 18% to 40%, and decreases the time to first request of postoperative analgesia by approximately 30%.

Background and Objectives: Practitioners mix faster-onset, intermediate-duration local anesthetics (LAs) with slower-onset, long-duration LAs to get fast peripheral nerve block (PNB) onset and long duration. We hypothesized that 1.5% mepivacaine (with epinephrine) (mepivacaine) or 1.5% mepivacaine (with epinephrine) mixed with 0.5% bupivacaine (mixed) would reduce PNB sensory onset by 20% or more versus 0.5% bupivacaine alone (bupivacaine)., Methods: Patients (n = 93) having arm surgery were randomized to 1 of the 3 LA groups. Infraclavicular PNB was administered using 1 of 3 LAs; afterward, PNB sensory (motor) onset, duration, and other outcomes were assessed. Subjects, physicians, and the biostatistician were blinded until study completion., Results: Median (interquartile range) PNB sensory onset (in minutes) was as follows: mepivacaine, 3 (3-6); mixed, 6 (3-6); and bupivacaine, 6 (3-12) (P = 0.0085). Mepivacaine PNB sensory onset was not faster than mixed (P = 0.57), but mixed was faster than bupivacaine (P = 0.0035). More mixed group patients achieved PNB sensory onset (0.81) versus the bupivacaine group (0.54) at 6 mins. Median (interquartile range) PNB motor onset (in minutes) was as follows: mepivacaine, 15 (12-18); mixed, 17 (12-21); and bupivacaine, 21 (12-24) (P < 0.0001). Median sensory and motor PNB duration (in minutes) was as follows: mepivacaine, 281 and 320; mixed, 439 and 556; and bupivacaine, 850 and 1109. Sensory (motor) PNB duration was shorter with mepivacaine versus mixed (P < 0.0001, P = 0.034), and mixed was shorter versus bupivacaine (P = 0.0243, P = 0.034)., Conclusions: Mixing 1.5% mepivacaine (with epinephrine) with 0.5% bupivacaine speeds up PNB sensory (motor) onset compared with 0.5% bupivacaine alone.

Background: Despite good success rates reported with ultrasound-guided supraclavicular block using 1 or multiple injections, no consensus exists on the best technique to use. We designed this study to test the hypothesis that a double-injection technique would hasten the onset of sensory block., Methods: Adult patients undergoing hand, wrist, or elbow surgery were enrolled in this prospective double-blind randomized study. Blocks were performed under ultrasound guidance. In group S (single injection), 30 mL of mepivacaine 1.5% was injected at the junction of the subclavian artery and the first rib. In group D (double injection), 15 mL of the same solution was injected at the site described above, then 15 mL was injected in the most superficial portion of the lateral aspect of the cluster formed by the brachial plexus trunks and divisions. The primary end point was the rate of complete sensory block at 15 mins. Secondary end points were the rates of sensory, motor, and surgical blocks and procedure time., Results: Fifty-one patients were randomized to each group. The rate of complete sensory block was similar at 15 mins (group S: 49% [95% confidence interval, 36%-62%], group D: 53% [95% confidence interval, 40%-66%]; P = 0.80) and at each time interval. The rates of complete motor block and surgical block success were similar between groups. The procedure time was shorter in group S (179 ± 104 vs 275 ± 137 secs; P < 0.01)., Conclusions: The double-injection technique offers no benefit over a single injection for the performance of an ultrasound-guided supraclavicular block.

Background: Although the efficacy of single-injection supraclavicular nerve blocks is well established, no controlled study of continuous supraclavicular blocks is available, and their relative risks and benefits remain unknown. In contrast, the analgesia provided by continuous infraclavicular nerve blocks has been validated in randomized controlled trials. We therefore compared supraclavicular with infraclavicular perineural local anesthetic infusion following distal upper-extremity surgery., Methods: Preoperatively, subjects were randomly assigned to receive a brachial plexus perineural catheter in either the infraclavicular or supraclavicular location using an ultrasound-guided nonstimulating catheter technique. Postoperatively, subjects were discharged home with a portable pump (400-mL reservoir) infusing 0.2% ropivacaine (basal rate of 8 mL/hr; 4-mL bolus dose; 30-min lockout interval). Subjects were followed up by telephone on an outpatient basis. The primary outcome was the average pain score on the day after surgery., Results: Sixty subjects were enrolled, with 31 and 29 randomized to receive an infraclavicular and supraclavicular catheter, respectively. All perineural catheters were successfully placed per protocol. Because of protocol violations and missing data, an intention-to-treat analysis was not used; rather, only subjects with catheters in situ and whom we were able to contact were included in the analyses. The day after surgery, subjects in the infraclavicular group reported average pain as median of 2.0 (10th-90th percentiles, 0.5-6.0) compared with 4.0 (10th-90th percentiles, 0.6-7.7) in the supraclavicular group (P = 0.025). Similarly, least pain scores (numeric rating scale) on postoperative day 1 were lower in the infraclavicular group compared with the supraclavicular group (0.5 [10th-90th percentiles, 0.0-3.5] vs 2.0 [10th-90th percentiles, 0.0-4.7], respectively; P = 0.040). Subjects in the infraclavicular group required less rescue oral analgesic (oxycodone, in milligrams) for breakthrough pain in the 18 to 24 hrs after surgery compared with the supraclavicular group (0.0 [10th-90th percentiles, 0.0-5.0] vs 5.0 [10th-90th percentiles, 0.0-15.0], respectively; P = 0.048). There were no statistically significant differences in other secondary outcomes., Conclusions: A local anesthetic infusion via an infraclavicular perineural catheter provides superior analgesia compared with a supraclavicular perineural catheter.

Objectives: The American Society of Regional Anesthesia and Pain Medicine charged an expert panel to examine the evidence basis for ultrasound guidance as a nerve localization tool in the clinical practices of regional anesthesia and interventional pain medicine., Methods: The panel searched, examined, and assessed the literature of ultrasound-guided regional anesthesia (UGRA) from the past 20 years. The qualities of studies were graded using the Jadad score. Strength of evidence and recommendations were graded using an accepted rating tool., Results: The panel made specific literature-based assessments concerning the relative advantages and limitations of UGRA relative to traditional nerve localization methods as they pertained to block characteristics and complications. Assessments and recommendations were made for upper and lower extremity, neuraxial, and truncal blocks and include pediatrics and interventional pain medicine., Conclusions: Ultrasound guidance improves block characteristics (particularly performance time and surrogate measures of success) that are often block specific and that may impart an efficiency advantage depending on individual practitioner circumstances. Evidence for UGRA impacting patient safety is currently limited to the demonstration of improvements in the frequency of surrogate events for serious complications.

This article qualitatively assesses and summarizes randomized, controlled studies regarding benefits of ultrasound (US) for brachial plexus block and also examines those studies that have compared different brachial plexus block techniques using US.Studies were identified by a search of PUBMED and EMBASE databases using the MeSH terms anesthetic techniques, brachial plexus, and ultrasound. Included studies were limited to randomized trials that compared a US technique with another accepted method of performing brachial plexus block or those studies that compared 2 different US-guided techniques. Studies were further classified according to methodological quality using accepted methods. Quality scores were compared using Mann-Whitney U test, and significance assumed at P < 0.05.Twenty-five studies met inclusion criteria, with 19 studies comparing US techniques with other nerve location methods and 6 studies comparing different US techniques. Of the former, there was convincing evidence to support the use of US, with 15 of 19 studies demonstrating improved outcomes compared with existing techniques.Ultrasound provides significant advantages when performing brachial plexus block including faster sensory block onset and greater block success.

Background and Objectives: Peripheral nerve stimulation (PNS) may provide analgesia for neuropathic pain syndromes in that nerve distribution. PNS electrode placement using ultrasound (US) guidance for upper extremity pain syndromes has not been reported. Existing anchoring technology may allow permanent implantation without significant migration., Methods: Three cadaver midhumeral fresh frozen upper extremity specimens were studied. US scanning was performed, targeting electrode placement at the radial, ulnar, and median nerves. Leads were anchored in the superficial fascia. The targeted nerves were exposed by careful dissection. Visual inspection for gross nerve damage, and electrode proximity to the nerve was performed. After confirmation of adequate lead placement, 2 extremities were sutured and placed in a continuous passive motion (CPM) machine for 21 hours to simulate activity. Each electrode was assessed for migration., Results: Acceptable locations for US-guided electrode placement were: radial nerve approximately 10-14 cm superior to the lateral epicondyle; median nerve approximately 6 cm below the antecubital fossa; and ulnar nerve approximately 9 to 13 cm above the medial epicondyle. One electrode was placed at each site without difficulty. After careful exposure, visual inspection showed no gross nerve damage. Each electrode had at least 2 electrical contacts within 2 mm of the nerve sheath. At CPM termination, only the median nerve electrode on 1 cadaver extremity had migrated significantly., Conclusions: This new minimally invasive approach to lead placement requires further study to determine implantation criteria, optimal locations, anchoring techniques, and electrode design to define best clinical practice.

Background and Objectives: Nerve blocks frequently produce unusual altered perceptions in the extremities. We examined perceptual changes experienced after peripheral blocks., Methods: Fifty consecutive patients having an upper or lower extremity block for surgery participated in this prospective study. Patients were divided into 2 groups: upper extremity (n = 20) and lower extremity (n = 30). Each group was asked a list of questions about perceptions of limb sensation, length, weight, and location and given a detailed 2-point discrimination test over the V(1)-V(3) divisions of the trigeminal nerve prior to block and sedation. While the extremity was still blocked, the exam was repeated before postanesthesia care unit discharge., Results: In both groups, 98% of patients described altered limb perception. The perceptions in the upper extremity were: heaviness, 60%; numbness, 50%; warmth, 40%; pain, 30%; full or fat, 20%; floating, 5%; shorter, 0%; or thinner, 10%. The perceptions in the lower extremity were: numbness, 75%; heaviness, 46%; warmth, 33%; pain, 32%; full or fat, 36%; floating, 25%; shorter, 18%, or thinner, 7%. Upper extremity block patients were more likely to describe the limb as lighter (P <.0001); the lower extremity group was more likely to describe the limb as numb (P =.01) or floating (P =.0002). There was no difference in the ability to correctly identify the location of the limb between the groups. There was no difference in 2-point discrimination between each assessment for either group., Conclusion: The results of this study confirm and quantify the perceptions experienced by patients undergoing upper and lower extremity blocks. These perceptions are prevalent. This knowledge is helpful in providing patients with accurate preoperative preparation. Further investigation is warranted to determine the neurologic etiology of these observations.