Ultrasound-guided suprafascial plane block for forearm AVF angioplasty: a motor-sparing, image-standardizable alternative to brachial plexus block in a single-center retrospective comparison

Ultrasound-guided suprafascial plane block for forearm AVF angioplasty: a motor-sparing, image-standardizable alternative to brachial plexus block in a single-center retrospective comparison | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Ultrasound-guided suprafascial plane block for forearm AVF angioplasty: a motor-sparing, image-standardizable alternative to brachial plexus block in a single-center retrospective comparison Wenshen Pu, Limei Dong, Zhican He, Zhihu Chen, Bingjie Wang, Zhangjian Xu, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8490214/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 12 You are reading this latest preprint version Abstract Background Balloon angioplasty for forearm arteriovenous fistula (AVF) often provokes substantial pain during inflation. Objective To compare an ultrasound-guided suprafascial plane block (SFPB) with brachial plexus block (BPB) during forearm AVF percutaneous transluminal angioplasty (PTA), focusing on analgesic effectiveness and safety. Methods Single-center, retrospective comparative study (January 1–December 31, 2025) of consecutive adults with forearm radiocephalic AVFs. SFPB targeted the superficial fascia–deep adipose tissue (SF–DAT) interface after sheath placement and guidewire traversal; BPB was completed before venipuncture. The primary endpoint was peak-inflation pain on the numeric rating scale (NRS, 0–10). Secondary outcomes included rescue analgesia, procedure time, block-related complications, and short-term patency. Results We analyzed SFPB (n=32) and BPB (n=35). The primary endpoint favored BPB (mean peak-inflation NRS 1.54 ± 0.74 vs 2.66 ± 0.85; mean difference −1.12, 95% CI −1.51 to −0.73; p =0.0038). Importantly, SFPB still met the prespecified adequacy threshold in most cases (NRS ≤3 in 87.5%, 28/32) without rescue or conversion and with no transient motor block, whereas BPB produced universal transient motor block and hoarseness in 2 patients. Procedure time did not differ significantly (70.77 ± 37.51 vs 87.49 ± 36.21 min; p =0.0613). One- and three-month primary patency was 100% in both groups. Conclusions SFPB provided clinically adequate, motor-sparing analgesia that is compatible with outpatient workflow, while BPB achieved lower NRS at the expense of motor involvement. These findings support SFPB as a pragmatic, image-standardizable alternative; prospective trials are warranted. arteriovenous fistula angioplasty suprafascial plane block brachial plexus block ultrasound guidance motor-sparing analgesia Figures Figure 1 Figure 2 Figure 3 Introduction Arteriovenous fistula (AVF) is the preferred vascular access for maintenance hemodialysis because of superior long-term patency and lower infection risk compared with grafts and catheters[ 1 ]. Percutaneous transluminal angioplasty (PTA) is the guideline-endorsed first-line therapy for AVF dysfunction/stenosis in routine practice[ 1 , 2 ]. During AVF-PTA, high-pressure balloon inflation frequently provokes substantial pain that jeopardizes cooperation and disrupts outpatient workflow, underscoring the need for motor-sparing, layer-specific analgesia[ 3 ]. Traditional local infiltration anesthesia (LA) often provides incomplete longitudinal coverage of nociception arising from the dilated venous segment[ 3 , 4 ]. Ultrasound-guided selective nerve blocks (UGNB)—including brachial plexus block (BPB) and targeted superficial cutaneous blocks such as the superficial radial nerve (SRN) and lateral antebrachial cutaneous nerve (LABCN)—can yield superior intraprocedural analgesia versus LA during AVF interventions, but at the cost of greater technical complexity, additional setup time, and a non-trivial risk of transient motor impairment and other block-related adverse events[ 3 – 7 ]. Building on the concept of fascial-plane blocks (FPBs)—which deposit local anesthetic in interfascial planes where bulk flow and diffusion generate sheet-like spread with small volumes—we focused on a suprafascial approach tailored to AVF-PTA[ 8 , 9 ]. Specifically, we targeted the deep surface of the superficial fascia (the SF–DAT interface; SF, superficial fascia; DAT, deep adipose tissue), which is ultrasonographically distinguishable from the deep fascia (DF) and permits image-verifiable execution (plane separation; thin-sheet continuity and extent)[ 9 – 11 ]. Anatomically, the cephalic vein runs within the superficial fascial/subcutaneous system of the distal forearm and antecubital fossa, aligning with a suprafascial target[ 12 ]. In the same region, the SRN and LABCN course near the cephalic vein, supporting a superficial, plane-guided strategy that prioritizes sensory coverage while minimizing deep passes and motor involvement[ 12 , 13 ]. On this basis, we developed an ultrasound-guided suprafascial plane block (SFPB) for AVF-PTA. The block is performed after sheath insertion and guidewire traversal, using segmental micro-aliquots along the intended angioplasty segment to create a continuous suprafascial separation on the deep surface of the SF. We prespecified process metrics (image-confirmed plane hit and continuous-sheet coverage), analgesic outcomes (peak-inflation numeric rating scale, NRS, 0–10; need for rescue analgesia), and safety endpoints, hypothesizing that SFPB would achieve acceptable pain control without compromising venous compressibility or flow, and that standardized ultrasound metrics would enhance reproducibility and training in routine outpatient PTA. Methods Study design, setting, and period Single-center, retrospective comparative study of consecutive adults who underwent forearm AVF-PTA between January 1 and November 31, 2025. Cases receiving SFPB constituted the intervention cohort; those receiving BPB served as the comparison cohort. Ultrasound (US; and digital subtraction angiography [DSA] when appropriate) was used for guidance and documentation. This study focused on venous targets of forearm AVF; cases planned for angioplasty involving the anastomosis or radial/ulnar arteries were excluded by design. Eligibility Inclusion: Adults (≥18 years) with forearm radiocephalic AVF undergoing balloon angioplasty for dysfunction/stenosis. Exclusion: Upper-arm AVF; active infection at the intended injection site; coagulopathy precluding block; combined arterial targets planned for angioplasty (i.e., anastomosis or radial/ulnar artery segments); or missing primary pain outcome. Forearm lesion taxonomy for analysis We used a three-tier, mutually exclusive taxonomy: (1) Juxta-anastomotic outflow (≤5 cm): the venous segment within 5 cm distal to the anastomosis; (2) Cannulation segment (mid-forearm): the routinely needled forearm cephalic-vein zone outside the juxta-anastomotic area, extending toward the antecubital fossa; (3) Combined: lesions involving both segments. This scheme was applied consistently in baseline summaries and between-group comparisons. Peri-procedural workflow SFPB cohort: After venous access, sheath placement and guidewire traversal across the lesion were completed first to avoid luminal compression by local anesthetic spread; SFPB was then performed, followed by balloon angioplasty. BPB cohort: BPB was completed before venipuncture and sheath insertion, and angioplasty proceeded under the established block. Local anesthetic formulation (identical for SFPB and BPB) Lidocaine 0.1 g/5 mL (20 mg/mL) + ropivacaine 100 mg/10 mL (10 mg/mL) + 5 mL normal saline, yielding a final volume of 20 mL with both lidocaine and ropivacaine at 5 mg/mL; no epinephrine. SFPB technique (suprafascial target) After sheath placement and guidewire traversal, a 10–18 MHz linear probe is aligned longitudinally to the CV. An in-plane needle advances to the SF–DAT interface, staying ≥3–5 mm lateral to the vein. Hydrolocation with 0.2–0.5 mL confirms a plane hit by creating a thin, continuous anechoic separation. Segmental micro-aliquots of 1–2 mL every 1–2 cm then form a continuous suprafascial sheet along the intended balloon segment (±1–2 cm extension if needed). The typical administered volume was 8–12 mL. Safety maneuvers include intermittent aspiration, avoidance of intravascular injection, correction of off-plane spread (subcutaneous or subfascial), and readiness for LAST management. BPB technique (comparator) Supraclavicular or infraclavicular BPB was performed under US guidance using the same mixture. Negative aspiration, fractionated injection, and real-time visualization were employed; the actual volume was tailored to sensory coverage with minimal motor involvement and recorded. Rescue and monitoring mirrored SFPB. Outcomes Primary outcome: Peak-inflation NRS (0–10) during ballooning; analgesic adequacy prespecified as NRS ≤3. Secondary outcomes: Rescue analgesia or conversion, procedure time, block-related complications (intravascular injection/LAST, hematoma/ecchymosis, venous perforation/occlusion, vasospasm requiring therapy, puncture-site infection ≤7 days, transient motor block), and primary patency at 1 and 3 months. Data collection and definitions Demographics, dialysis vintage, AVF vintage, lesion characteristics (taxonomy, count/length, minimal luminal diameter), intraprocedural events, and outcomes were abstracted by two investigators using a predefined template. Transient motor block was defined as new motor weakness in the fistula arm within the procedural period that resolved within 24 h without intervention. Statistical analysis Continuous variables are mean ± SD or median [IQR]; categorical variables n (%). Welch’s t-test or Mann–Whitney U test was used for continuous variables, χ² or Fisher’s exact test for categorical variables (two-sided, p <0.05). Analyses used IBM SPSS Statistics 23.0 (IBM, Armonk, NY, USA). Ethics The study protocol was reviewed and approved by the Baoshan People’s Hospital Ethics Committee (approval No. 202512-LLP-004-01). Given the retrospective design and use of de-identified data, the requirement for written informed consent was waived. The study complied with the Declaration of Helsinki and relevant institutional regulations. Clinical trial number: not applicable. Results Baseline characteristics and the three-tier lesion taxonomy were broadly comparable between groups (Table 1). The primary endpoint favored BPB (mean peak-inflation NRS 1.54 ± 0.74 vs 2.66 ± 0.85; mean difference −1.12, 95% CI −1.51 to −0.73; p =0.0038). Importantly, SFPB still met the prespecified adequacy threshold in most cases (NRS ≤3 in 87.5%, 28/32) with no rescue or conversion and no transient motor block. Procedure time did not differ significantly (70.77 ± 37.51 vs 87.49 ± 36.21 min; p =0.0613). Primary patency at 1 and 3 months was 100% in both cohorts. The technical workflow is shown in Figures 2–3. Safety events were rare. Transient motor block occurred in 0/32 with SFPB versus 35/35 with BPB ( p <0.001), and hoarseness occurred in 0/32 versus 2/35 ( p =0.4934). All other prespecified complications were 0/32 vs 0/35 ( p not estimable, “—” in Table 1). Table 1. Baseline characteristics and target taxonomy by anesthesia group. Variable SFPB (n=32) BPB (n=35) p value Baseline characteristics Age, years 60.53 ± 11.29 53.63 ± 15.03 0.0337 Dialysis vintage, years 2.36 ± 2.75 1.67 ± 1.53 0.4724 AVF vintage, years 2.35 ± 2.77 1.40 ± 1.08 0.3275 Sex (M/F) 21/11 22/13 1.000 Hemoglobin, g/L 117.38 ± 19.71 113.40 ± 19.93 0.4153 Platelet count, × 10^9/L 154.34 ± 48.43 159.57 ± 68.32 0.7213 Serum albumin, g/L 39.98 ± 5.30 40.94 ± 4.99 0.3368 Serum creatinine, μmol/L 841.67 ± 315.52 966.29 ± 382.50 0.2748 Lesion characteristics Lesions per patient, n 1.47 ± 0.57 1.50 ± 0.67 0.859 Minimal lumen diameter at stenosis, mm 1.31 ± 0.30 1.41 ± 0.37 0.4191 Lesion length, mm 27.11 ± 20.64 32.21 ± 14.37 0.0622 Procedural and analgesic outcomes Peak-inflation NRS (0–10) 2.66 ± 0.85 1.54 ± 0.74 0.0038 Procedure time, min 70.77 ± 37.51 87.49 ± 36.21 0.0613 Rescue sedation or conversion to UGNB 0 (0%) 0 (0%) — Target segments ballooned, n (%) 0.614 Outflow only 11 (34.4%) 16 (45.7%) Forearm cephalic only 12 (37.5%) 10 (28.6%) Outflow + forearm cephalic 9 (28.1%) 9 (25.7%) Complications, n (% of patients) Intravascular injection / LAST 0 (0%) 0 (0%) — Transient motor block 0 (0%) 35 (100%) <0.001 Hematoma/ecchymosis 0 (0%) 0 (0%) — Venous perforation/occlusion 0 (0%) 0 (0%) — Vasospasm requiring therapy 0 (0%) 0 (0%) — Puncture-site infection (≤7 d) 0 (0%) 0 (0%) — Hoarseness 0 (0.0%) 2 (5.7%) 0.4934 Patency outcomes Primary patency at 1 month, % 32 (100%) 35 (100%) — Primary patency at 3 months, % 32 (100%) 35 (100%) — Data are mean ± SD, median [IQR], or n (%), as appropriate. P values from Welch’s t-test or Mann–Whitney U test for continuous variables, and χ² test or Fisher’s exact test for categorical variables (two-sided; significance threshold p<0.05). “—” indicates not estimable (both groups 0). Abbreviations: SFPB, suprafascial plane block; BPB, brachial plexus block; AVF, arteriovenous fistula; NRS, numeric rating scale; LAST, local anesthetic systemic toxicity; CV, cephalic vein; SF, superficial fascia; DAT, deep adipose tissue; DF, deep fascia; US, ultrasound. Discussion Pain during AVF-PTA typically peaks at balloon inflation and is clinically relevant in outpatient workflows, underscoring the need for motor-sparing, layer-specific analgesia[4,14]. We operationalized SFPB for forearm AVF-PTA: after sheath and wire, segmental micro-aliquots create a thin, continuous sheet on the SF–DAT interface, shifting emphasis from nerve-seeking to plane-hitting plus sheet-formation. In this retrospective comparative series, we predefined image-verifiable criteria (plane hit and coverage) and evaluated analgesic effectiveness (peak-inflation NRS, no rescue) and block-related safety (intravascular injection, transient motor block, hematoma, puncture-site infection, LAST). Figures 1–3 illustrate the target plane, the stepwise workflow, and the consolidated process metrics. Even with statistically lower NRS under BPB, SFPB delivered clinically adequate analgesia without motor involvement, aligning with outpatient priorities. Mechanistically, FPBs place local anesthetic into interfascial spaces where bulk flow and diffusion generate sheet-like spread with small volumes[8,9]. SF–DAT was selected because it is reliably distinguishable from DF on ultrasound, enabling reproducible plane confirmation and continuous-sheet coverage[9–11]; the cephalic vein resides in the superficial fascial/subcutaneous system in the distal forearm/antecubital region, aligning the block with perivenous nociceptive inputs[15]; and SRN/LABCN course near the vein, favoring sensory coverage with minimal motor involvement[12,13]. We avoided SAT–SF (risk of under-analgesia from superficial spread) and subfascial DAT–DF (risk of myofascial tracking, reduced venous compressibility, transient motor involvement). Head-to-head plane comparisons in AVF-PTA are lacking; prospective trials contrasting SAT–SF vs SF–DAT vs subfascial spread on analgesia and hemodynamics are warranted. Against LA—which is focal and often fails to provide longitudinal coverage along the dilated venous segment—SFPB uses segmental, surface-matched deposition to improve coverage[3,4,7]. Compared with UGNB (e.g., BPB or targeted SRN/LABCN), SFPB aims to preserve motor function and reduce technical/setup burden; in our cohort, no rescue or conversion occurred under SFPB, whereas BPB predictably produced universal transient motor block and occasional hoarseness, reflecting known trade-offs in upper-extremity regional anesthesia[3–7]. Clinically, SFPB fits routine outpatient AVF-PTA because it provides analgesia sufficient for treatment while preserving motor function, is executed after sheath and wire without disrupting workflow, and is image-standardizable for training and audit. When targets involve the anastomosis/artery and nociception is deeper, our predefined escalation (same-plane top-up → selective UGNB or light sedation) remains appropriate[3,4,7]. Standardization hinged on timing (after sheath and wire), explicit plane targeting (≥3–5 mm lateral to the CV), hydrolocation-confirmed plane hit, and continuous-sheet coverage via micro-aliquots—steps that are image-verifiable and directly trainable[16–18]. Emphasizing sheet-formation rather than bulk volume along SF–DAT aims to maintain venous compressibility while ensuring coverage. Limitations include retrospective, non-randomized design, modest sample size, unblinded peak NRS, and unquantified inter-rater reliability for ultrasound process metrics. Future work should include randomized comparisons of SFPB vs UGNB, plane-level comparisons (SAT–SF vs SF–DAT vs subfascial), upper-arm validation, and pharmacokinetic/safety profiling, with standardized ultrasound endpoints for cross-center training/audit. The SFPB cohort was older on average; although analyses were unadjusted, this difference is unlikely to invalidate the primary analgesic findings. Conclusion SFPB delivered clinically sufficient, motor-sparing analgesia for forearm AVF-PTA without rescue or conversion and with excellent short-term patency. While BPB achieved lower mean NRS, it did so at the cost of universal transient motor block and occasional hoarseness, alongside greater setup and technical demands. Standardized, image-verifiable steps make SFPB reproducible and training-friendly. Prospective randomized studies should confirm these findings, compare plane-level strategies, and evaluate longer-term access outcomes. Declarations Funding This work was supported by the Baoshan Science and Technology Plan—2023 Joint Medical Research Special Project (Grant No. 2023bskjylqn005). The funder had no role in the design of the study; collection, analysis, or interpretation of data; writing of the report; or the decision to submit the article for publication. Data availability De-identified data and analysis code are available from the corresponding author upon reasonable request and with institutional approvals after publication. Ethics approval Approved by the Baoshan People’s Hospital Ethics Committee (No. 202512-LLP-004-01); consent requirement waived. Competing interests The authors declare no competing interests related to this work. References KDOQI clinical practice guideline for vascular access 2019 update. Am J Kidney Dis 2020;75:S1–164. https://doi.org/10.1053/j.ajkd.2019.12.001. Schmidli J, Widmer MK, Basile C, De Donato G, Gallieni M, Gibbons CP, et al. Editor’s choice – vascular access: 2018 clinical practice guidelines of the european society for vascular surgery (ESVS). Eur J Vasc Endovasc Surg 2018;55:757–818. https://doi.org/10.1016/j.ejvs.2018.02.001. Wen J, Zhan S, Wang Y, Zhang L, Li H. The efficacy of ultrasound-guided selective nerve block in the endovascular treatment of arteriovenous fistulas. 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16:15:23","extension":"xml","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":70471,"visible":true,"origin":"","legend":"","description":"","filename":"46835f7c6a2645cdba92ff832032600f1structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8490214/v1/6599baa278e5c4c2df9cfd79.xml"},{"id":100069676,"identity":"c35c38e0-c5da-4ae2-ab9e-c55e9562d3aa","added_by":"auto","created_at":"2026-01-12 16:15:09","extension":"html","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":80794,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8490214/v1/94ee08cbb8827a5e140182e5.html"},{"id":100069911,"identity":"7346a19c-fa1f-4ccf-8870-b2de5073370c","added_by":"auto","created_at":"2026-01-12 16:15:24","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":116084,"visible":true,"origin":"","legend":"\u003cp\u003eSFPB for forearm AVF-PTA: target plane and anatomical layers. Schematic of distal forearm micro-anatomy (skin → superficial adipose tissue [SAT] → superficial fascia [SF] → deep adipose tissue [DAT] → deep fascia [DF] → muscle). The needle advances in-plane to the SF–DAT interface, depositing local anesthetic to cleanly separate SF from adjacent adipose tissue and form a continuous anechoic sheet along the intended balloon segment.\u003cbr\u003e\n Abbreviations: CV, cephalic vein; SAT, superficial adipose tissue; SF, superficial fascia; DAT, deep adipose tissue; DF, deep fascia; SFPB, suprafascial plane block; AVF, arteriovenous fistula; PTA, percutaneous transluminal angioplasty.\u003c/p\u003e","description":"","filename":"floatimage1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8490214/v1/2d1522d02d5f46261c08d702.jpg"},{"id":100069917,"identity":"90fbabe3-f23d-4fee-8d37-676b55335fe1","added_by":"auto","created_at":"2026-01-12 16:15:25","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1876077,"visible":true,"origin":"","legend":"\u003cp\u003eSFPB stepwise technique during forearm AVF-PTA (Panels A–D): A, setup after access and wire traversal; B, in-plane approach and hydrolocation with a 0.7 × 80 mm thin-walled long-bevel (TWLB) needle; C, ultrasound confirmation of plane hit; D, segmental micro-aliquots to form a continuous anechoic sheet.\u003cbr\u003e\n Abbreviations: SFPB, suprafascial plane block; AVF, arteriovenous fistula; PTA, percutaneous transluminal angioplasty; CV, cephalic vein; SF, superficial fascia; DAT, deep adipose tissue; DF, deep fascia; US, ultrasound; TWLB, thin-walled long-bevel; 0.7 × 80 mm indicates needle outer diameter × length.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8490214/v1/fc7efb8add44aff1b84ddc54.png"},{"id":100069964,"identity":"596a6702-e74e-4f7b-b4b3-6483532e8fd4","added_by":"auto","created_at":"2026-01-12 16:15:35","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":199788,"visible":true,"origin":"","legend":"\u003cp\u003eWorkflow of ultrasound-guided SFPB during forearm AVF-PTA.\u003c/p\u003e\n\u003cp\u003eAbbreviations: AVF, arteriovenous fistula; CV, cephalic vein; SF, superficial fascia; DAT, deep adipose tissue; DF, deep fascia; SRN, superficial radial nerve; LABCN, lateral antebrachial cutaneous nerve; SFPB, suprafascial plane block; NRS, numeric rating scale; US, ultrasound; DSA, digital subtraction angiography; UGNB, ultrasound-guided nerve blocks; NS, normal saline; LAST, local anesthetic systemic toxicity.\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8490214/v1/2e4bd11e8a45f8c73c520b1b.jpeg"},{"id":100070854,"identity":"5e441745-a738-4ccb-87b0-d5626c7b2420","added_by":"auto","created_at":"2026-01-12 16:18:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3443813,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8490214/v1/975bca51-dca0-48d1-9b32-ab7eb842ff10.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Ultrasound-guided suprafascial plane block for forearm AVF angioplasty: a motor-sparing, image-standardizable alternative to brachial plexus block in a single-center retrospective comparison","fulltext":[{"header":"Introduction","content":"\u003cp\u003eArteriovenous fistula (AVF) is the preferred vascular access for maintenance hemodialysis because of superior long-term patency and lower infection risk compared with grafts and catheters[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Percutaneous transluminal angioplasty (PTA) is the guideline-endorsed first-line therapy for AVF dysfunction/stenosis in routine practice[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. During AVF-PTA, high-pressure balloon inflation frequently provokes substantial pain that jeopardizes cooperation and disrupts outpatient workflow, underscoring the need for motor-sparing, layer-specific analgesia[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTraditional local infiltration anesthesia (LA) often provides incomplete longitudinal coverage of nociception arising from the dilated venous segment[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Ultrasound-guided selective nerve blocks (UGNB)\u0026mdash;including brachial plexus block (BPB) and targeted superficial cutaneous blocks such as the superficial radial nerve (SRN) and lateral antebrachial cutaneous nerve (LABCN)\u0026mdash;can yield superior intraprocedural analgesia versus LA during AVF interventions, but at the cost of greater technical complexity, additional setup time, and a non-trivial risk of transient motor impairment and other block-related adverse events[\u003cspan additionalcitationids=\"CR4 CR5 CR6\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Building on the concept of fascial-plane blocks (FPBs)\u0026mdash;which deposit local anesthetic in interfascial planes where bulk flow and diffusion generate sheet-like spread with small volumes\u0026mdash;we focused on a suprafascial approach tailored to AVF-PTA[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Specifically, we targeted the deep surface of the superficial fascia (the SF\u0026ndash;DAT interface; SF, superficial fascia; DAT, deep adipose tissue), which is ultrasonographically distinguishable from the deep fascia (DF) and permits image-verifiable execution (plane separation; thin-sheet continuity and extent)[\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Anatomically, the cephalic vein runs within the superficial fascial/subcutaneous system of the distal forearm and antecubital fossa, aligning with a suprafascial target[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. In the same region, the SRN and LABCN course near the cephalic vein, supporting a superficial, plane-guided strategy that prioritizes sensory coverage while minimizing deep passes and motor involvement[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. On this basis, we developed an ultrasound-guided suprafascial plane block (SFPB) for AVF-PTA. The block is performed after sheath insertion and guidewire traversal, using segmental micro-aliquots along the intended angioplasty segment to create a continuous suprafascial separation on the deep surface of the SF. We prespecified process metrics (image-confirmed plane hit and continuous-sheet coverage), analgesic outcomes (peak-inflation numeric rating scale, NRS, 0\u0026ndash;10; need for rescue analgesia), and safety endpoints, hypothesizing that SFPB would achieve acceptable pain control without compromising venous compressibility or flow, and that standardized ultrasound metrics would enhance reproducibility and training in routine outpatient PTA.\u003c/p\u003e"},{"header":"Methods","content":"\u003ch3\u003eStudy design, setting, and period\u003c/h3\u003e\n\u003cp\u003eSingle-center, retrospective comparative study of consecutive adults who underwent forearm AVF-PTA between January 1 and November 31, 2025. Cases receiving SFPB constituted the intervention cohort; those receiving BPB served as the comparison cohort. Ultrasound (US; and digital subtraction angiography [DSA] when appropriate) was used for guidance and documentation. This study focused on venous targets of forearm AVF; cases planned for angioplasty involving the anastomosis or radial/ulnar arteries were excluded by design.\u003c/p\u003e\n\u003ch3\u003eEligibility\u003c/h3\u003e\n\u003cp\u003eInclusion: Adults (\u0026ge;18 years) with forearm radiocephalic AVF undergoing balloon angioplasty for dysfunction/stenosis.\u003cbr\u003e\u0026nbsp;Exclusion: Upper-arm AVF; active infection at the intended injection site; coagulopathy precluding block; combined arterial targets planned for angioplasty (i.e., anastomosis or radial/ulnar artery segments); or missing primary pain outcome.\u0026nbsp;\u003c/p\u003e\n\u003ch3\u003eForearm lesion taxonomy for analysis\u003c/h3\u003e\n\u003cp\u003eWe used a three-tier, mutually exclusive taxonomy:\u003cbr\u003e\u0026nbsp;(1) Juxta-anastomotic outflow (\u0026le;5 cm): the venous segment within 5 cm distal to the anastomosis;\u003cbr\u003e\u0026nbsp;(2) Cannulation segment (mid-forearm): the routinely needled forearm cephalic-vein zone outside the juxta-anastomotic area, extending toward the antecubital fossa;\u003cbr\u003e\u0026nbsp;(3) Combined: lesions involving both segments.\u003cbr\u003e\u0026nbsp;This scheme was applied consistently in baseline summaries and between-group comparisons.\u003c/p\u003e\n\u003ch3\u003ePeri-procedural workflow\u003c/h3\u003e\n\u003cp\u003eSFPB cohort: After venous access, sheath placement and guidewire traversal across the lesion were completed first to avoid luminal compression by local anesthetic spread; SFPB was then performed, followed by balloon angioplasty.\u003cbr\u003e\u0026nbsp;BPB cohort: BPB was completed before venipuncture and sheath insertion, and angioplasty proceeded under the established block.\u003c/p\u003e\n\u003ch3\u003eLocal anesthetic formulation (identical for SFPB and BPB)\u003c/h3\u003e\n\u003cp\u003eLidocaine 0.1 g/5 mL (20 mg/mL) + ropivacaine 100 mg/10 mL (10 mg/mL) + 5 mL normal saline, yielding a final volume of 20 mL with both lidocaine and ropivacaine at 5 mg/mL; no epinephrine.\u003c/p\u003e\n\u003ch3\u003eSFPB technique (suprafascial target)\u003c/h3\u003e\n\u003cp\u003eAfter sheath placement and guidewire traversal, a 10\u0026ndash;18 MHz linear probe is aligned longitudinally to the CV. An in-plane needle advances to the SF\u0026ndash;DAT interface, staying \u0026ge;3\u0026ndash;5 mm lateral to the vein. Hydrolocation with 0.2\u0026ndash;0.5 mL confirms a plane hit by creating a thin, continuous anechoic separation. Segmental micro-aliquots of 1\u0026ndash;2 mL every 1\u0026ndash;2 cm then form a continuous suprafascial sheet along the intended balloon segment (\u0026plusmn;1\u0026ndash;2 cm extension if needed). The typical administered volume was 8\u0026ndash;12 mL. Safety maneuvers include intermittent aspiration, avoidance of intravascular injection, correction of off-plane spread (subcutaneous or subfascial), and readiness for LAST management.\u003c/p\u003e\n\u003ch3\u003eBPB technique (comparator)\u003c/h3\u003e\n\u003cp\u003eSupraclavicular or infraclavicular BPB was performed under US guidance using the same mixture. Negative aspiration, fractionated injection, and real-time visualization were employed; the actual volume was tailored to sensory coverage with minimal motor involvement and recorded. Rescue and monitoring mirrored SFPB.\u003c/p\u003e\n\u003ch3\u003eOutcomes\u003c/h3\u003e\n\u003cp\u003ePrimary outcome: Peak-inflation NRS (0\u0026ndash;10) during ballooning; analgesic adequacy prespecified as NRS \u0026le;3.\u003cbr\u003e\u0026nbsp;Secondary outcomes: Rescue analgesia or conversion, procedure time, block-related complications (intravascular injection/LAST, hematoma/ecchymosis, venous perforation/occlusion, vasospasm requiring therapy, puncture-site infection \u0026le;7 days, transient motor block), and primary patency at 1 and 3 months.\u003c/p\u003e\n\u003ch3\u003eData collection and definitions\u003c/h3\u003e\n\u003cp\u003eDemographics, dialysis vintage, AVF vintage, lesion characteristics (taxonomy, count/length, minimal luminal diameter), intraprocedural events, and outcomes were abstracted by two investigators using a predefined template. Transient motor block was defined as new motor weakness in the fistula arm within the procedural period that resolved within 24 h without intervention.\u003c/p\u003e\n\u003ch3\u003eStatistical analysis\u003c/h3\u003e\n\u003cp\u003eContinuous variables are mean \u0026plusmn; SD or median [IQR]; categorical variables n (%). Welch\u0026rsquo;s t-test or Mann\u0026ndash;Whitney U test was used for continuous variables, \u0026chi;\u0026sup2; or Fisher\u0026rsquo;s exact test for categorical variables (two-sided, \u003cem\u003ep\u003c/em\u003e\u0026lt;0.05). Analyses used IBM SPSS Statistics 23.0 (IBM, Armonk, NY, USA).\u003c/p\u003e\n\u003ch3\u003eEthics\u003c/h3\u003e\n\u003cp\u003eThe study protocol was reviewed and approved by the Baoshan People\u0026rsquo;s Hospital Ethics Committee (approval No. 202512-LLP-004-01). Given the retrospective design and use of de-identified data, the requirement for written informed consent was waived. The study complied with the Declaration of Helsinki and relevant institutional regulations. Clinical trial number: not applicable.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eBaseline characteristics and the three-tier lesion taxonomy were broadly comparable between groups (Table 1). The primary endpoint favored BPB (mean peak-inflation NRS 1.54 \u0026plusmn; 0.74 vs 2.66 \u0026plusmn; 0.85; mean difference \u0026minus;1.12, 95% CI \u0026minus;1.51 to \u0026minus;0.73; \u003cem\u003ep\u003c/em\u003e=0.0038). Importantly, SFPB still met the prespecified adequacy threshold in most cases (NRS \u0026le;3 in 87.5%, 28/32) with no rescue or conversion and no transient motor block. Procedure time did not differ significantly (70.77 \u0026plusmn; 37.51 vs 87.49 \u0026plusmn; 36.21 min; \u003cem\u003ep\u003c/em\u003e=0.0613). Primary patency at 1 and 3 months was 100% in both cohorts. The technical workflow is shown in Figures 2\u0026ndash;3.\u003c/p\u003e\n\u003cp\u003eSafety events were rare. Transient motor block occurred in 0/32 with SFPB versus 35/35 with BPB (\u003cem\u003ep\u003c/em\u003e\u0026lt;0.001), and hoarseness occurred in 0/32 versus 2/35 (\u003cem\u003ep\u003c/em\u003e=0.4934). All other prespecified complications were 0/32 vs 0/35 (\u003cem\u003ep\u003c/em\u003e not estimable, \u0026ldquo;\u0026mdash;\u0026rdquo; in Table 1).\u003c/p\u003e\n\u003cp\u003eTable 1. Baseline characteristics and target taxonomy by anesthesia group.\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"698\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eVariable\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003eSFPB (n=32)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003eBPB (n=35)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eBaseline characteristics\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eAge, years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e60.53 \u0026plusmn; 11.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e53.63 \u0026plusmn; 15.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.0337\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eDialysis vintage, years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e2.36 \u0026plusmn; 2.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e1.67 \u0026plusmn; 1.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.4724\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eAVF vintage, years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e2.35 \u0026plusmn; 2.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e1.40 \u0026plusmn; 1.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.3275\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eSex (M/F)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e21/11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e22/13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e1.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eHemoglobin, g/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e117.38 \u0026plusmn; 19.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e113.40 \u0026plusmn; 19.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.4153\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003ePlatelet count, \u0026times; 10^9/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e154.34 \u0026plusmn; 48.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e159.57 \u0026plusmn; 68.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.7213\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eSerum albumin, g/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e39.98 \u0026plusmn; 5.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e40.94 \u0026plusmn; 4.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.3368\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eSerum creatinine, \u0026mu;mol/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e841.67 \u0026plusmn; 315.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e966.29 \u0026plusmn; 382.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.2748\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eLesion characteristics\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eLesions per patient, n\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e1.47 \u0026plusmn; 0.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e1.50 \u0026plusmn; 0.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.859\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eMinimal lumen diameter at stenosis, mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e1.31 \u0026plusmn; 0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e1.41 \u0026plusmn; 0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.4191\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eLesion length, mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e27.11 \u0026plusmn; 20.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e32.21 \u0026plusmn; 14.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.0622\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eProcedural and analgesic outcomes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003ePeak-inflation NRS (0\u0026ndash;10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e2.66 \u0026plusmn; 0.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e1.54 \u0026plusmn; 0.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.0038\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eProcedure time, min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e70.77 \u0026plusmn; 37.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e87.49 \u0026plusmn; 36.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.0613\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eRescue sedation or conversion to UGNB\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e0 (0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e0 (0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eTarget segments ballooned, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.614\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 296px;\"\u003e\n \u003cp\u003eOutflow only\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e11 (34.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e16 (45.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 296px;\"\u003e\n \u003cp\u003eForearm cephalic only\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e12 (37.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e10 (28.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 296px;\"\u003e\n \u003cp\u003eOutflow + forearm cephalic\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e9 (28.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e9 (25.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eComplications, n (% of patients)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eIntravascular injection / LAST\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e0 (0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e0 (0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eTransient motor block\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e0 (0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e35 (100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eHematoma/ecchymosis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e0 (0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e0 (0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eVenous perforation/occlusion\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e0 (0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e0 (0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003eVasospasm requiring therapy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e0 (0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e0 (0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003ePuncture-site infection (\u0026le;7 d)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e0 (0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e0 (0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 296px;\"\u003e\n \u003cp\u003eHoarseness\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e0 (0.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e2 (5.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.4934\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003ePatency outcomes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003ePrimary patency at 1 month, %\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e32 (100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e35 (100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 296px;\"\u003e\n \u003cp\u003ePrimary patency at 3 months, %\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 141px;\"\u003e\n \u003cp\u003e32 (100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 138px;\"\u003e\n \u003cp\u003e35 (100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eData are mean \u0026plusmn; SD, median [IQR], or n (%), as appropriate. \u003cem\u003eP\u003c/em\u003e values from Welch\u0026rsquo;s t-test or Mann\u0026ndash;Whitney U test for continuous variables, and \u0026chi;\u0026sup2; test or Fisher\u0026rsquo;s exact test for categorical variables (two-sided; significance threshold p\u0026lt;0.05). \u0026ldquo;\u0026mdash;\u0026rdquo; indicates not estimable (both groups 0). Abbreviations: SFPB, suprafascial plane block; BPB, brachial plexus block; AVF, arteriovenous fistula; NRS, numeric rating scale; LAST, local anesthetic systemic toxicity; CV, cephalic vein; SF, superficial fascia; DAT, deep adipose tissue; DF, deep fascia; US, ultrasound.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003ePain during AVF-PTA typically peaks at balloon inflation and is clinically relevant in outpatient workflows, underscoring the need for motor-sparing, layer-specific analgesia[4,14]. We operationalized SFPB for forearm AVF-PTA: after sheath and wire, segmental micro-aliquots create a thin, continuous sheet on the SF\u0026ndash;DAT interface, shifting emphasis from nerve-seeking to plane-hitting plus sheet-formation. In this retrospective comparative series, we predefined image-verifiable criteria (plane hit and coverage) and evaluated analgesic effectiveness (peak-inflation NRS, no rescue) and block-related safety (intravascular injection, transient motor block, hematoma, puncture-site infection, LAST). Figures 1\u0026ndash;3 illustrate the target plane, the stepwise workflow, and the consolidated process metrics. Even with statistically lower NRS under BPB, SFPB delivered clinically adequate analgesia without motor involvement, aligning with outpatient priorities.\u003c/p\u003e\n\u003cp\u003eMechanistically, FPBs place local anesthetic into interfascial spaces where bulk flow and diffusion generate sheet-like spread with small volumes[8,9]. SF\u0026ndash;DAT was selected because it is reliably distinguishable from DF on ultrasound, enabling reproducible plane confirmation and continuous-sheet coverage[9\u0026ndash;11]; the cephalic vein resides in the superficial fascial/subcutaneous system in the distal forearm/antecubital region, aligning the block with perivenous nociceptive inputs[15]; and SRN/LABCN course near the vein, favoring sensory coverage with minimal motor involvement[12,13]. We avoided SAT\u0026ndash;SF (risk of under-analgesia from superficial spread) and subfascial DAT\u0026ndash;DF (risk of myofascial tracking, reduced venous compressibility, transient motor involvement). Head-to-head plane comparisons in AVF-PTA are lacking; prospective trials contrasting SAT\u0026ndash;SF vs SF\u0026ndash;DAT vs subfascial spread on analgesia and hemodynamics are warranted.\u003c/p\u003e\n\u003cp\u003eAgainst LA\u0026mdash;which is focal and often fails to provide longitudinal coverage along the dilated venous segment\u0026mdash;SFPB uses segmental, surface-matched deposition to improve coverage[3,4,7]. Compared with UGNB (e.g., BPB or targeted SRN/LABCN), SFPB aims to preserve motor function and reduce technical/setup burden; in our cohort, no rescue or conversion occurred under SFPB, whereas BPB predictably produced universal transient motor block and occasional hoarseness, reflecting known trade-offs in upper-extremity regional anesthesia[3\u0026ndash;7]. Clinically, SFPB fits routine outpatient AVF-PTA because it provides analgesia sufficient for treatment while preserving motor function, is executed after sheath and wire without disrupting workflow, and is image-standardizable for training and audit. When targets involve the anastomosis/artery and nociception is deeper, our predefined escalation (same-plane top-up \u0026rarr; selective UGNB or light sedation) remains appropriate[3,4,7].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eStandardization hinged on timing (after sheath and wire), explicit plane targeting (\u0026ge;3\u0026ndash;5 mm lateral to the CV), hydrolocation-confirmed plane hit, and continuous-sheet coverage via micro-aliquots\u0026mdash;steps that are image-verifiable and directly trainable[16\u0026ndash;18]. Emphasizing sheet-formation rather than bulk volume along SF\u0026ndash;DAT aims to maintain venous compressibility while ensuring coverage.\u003c/p\u003e\n\u003cp\u003eLimitations include retrospective, non-randomized design, modest sample size, unblinded peak NRS, and unquantified inter-rater reliability for ultrasound process metrics. Future work should include randomized comparisons of SFPB vs UGNB, plane-level comparisons (SAT\u0026ndash;SF vs SF\u0026ndash;DAT vs subfascial), upper-arm validation, and pharmacokinetic/safety profiling, with standardized ultrasound endpoints for cross-center training/audit. The SFPB cohort was older on average; although analyses were unadjusted, this difference is unlikely to invalidate the primary analgesic findings.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eSFPB delivered clinically sufficient, motor-sparing analgesia for forearm AVF-PTA without rescue or conversion and with excellent short-term patency. While BPB achieved lower mean NRS, it did so at the cost of universal transient motor block and occasional hoarseness, alongside greater setup and technical demands. Standardized, image-verifiable steps make SFPB reproducible and training-friendly. Prospective randomized studies should confirm these findings, compare plane-level strategies, and evaluate longer-term access outcomes.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThis work was supported by the Baoshan Science and Technology Plan\u0026mdash;2023 Joint Medical Research Special Project (Grant No. 2023bskjylqn005). The funder had no role in the design of the study; collection, analysis, or interpretation of data; writing of the report; or the decision to submit the article for publication.\u003c/p\u003e\n\u003ch2\u003eData availability\u003c/h2\u003e\n\u003cp\u003eDe-identified data and analysis code are available from the corresponding author upon reasonable request and with institutional approvals after publication.\u003c/p\u003e\n\u003ch2\u003eEthics approval\u003c/h2\u003e\n\u003cp\u003eApproved by the Baoshan People\u0026rsquo;s Hospital Ethics Committee (No. 202512-LLP-004-01); consent requirement waived.\u003c/p\u003e\n\u003ch2\u003eCompeting interests\u003c/h2\u003e\n\u003cp\u003eThe authors declare no competing interests related to this work.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKDOQI clinical practice guideline for vascular access 2019 update. Am J Kidney Dis 2020;75:S1\u0026ndash;164. https://doi.org/10.1053/j.ajkd.2019.12.001.\u003c/li\u003e\n\u003cli\u003eSchmidli J, Widmer MK, Basile C, De Donato G, Gallieni M, Gibbons CP, et al. Editor\u0026rsquo;s choice \u0026ndash; vascular access: 2018 clinical practice guidelines of the european society for vascular surgery (ESVS). Eur J Vasc Endovasc Surg 2018;55:757\u0026ndash;818. https://doi.org/10.1016/j.ejvs.2018.02.001.\u003c/li\u003e\n\u003cli\u003eWen J, Zhan S, Wang Y, Zhang L, Li H. The efficacy of ultrasound-guided selective nerve block in the endovascular treatment of arteriovenous fistulas. Blood Purif 2025;54:240\u0026ndash;9. https://doi.org/10.1159/000543827.\u003c/li\u003e\n\u003cli\u003eWang X, Wang Y, Zhao Y, Li Y, Guo X, Zhang L, et al. Brachial plexus block versus local anesthesia for percutaneous transluminal angioplasty of dysfunctional arteriovenous fistula: 12-month results of a propensity score weighted study. Ren Fail 2025;47:2477834. https://doi.org/10.1080/0886022X.2025.2477834.\u003c/li\u003e\n\u003cli\u003eZhu W, Zhou R, Chen L, Chen Y, Huang L, Xia Y, et al. The ultrasound-guided selective nerve block in the upper arm: an approach of retaining the motor function in elbow. BMC Anesthesiol 2018;18:143. https://doi.org/10.1186/s12871-018-0584-7.\u003c/li\u003e\n\u003cli\u003eJones MR, Novitch MB, Sen S, Hernandez N, De Haan JB, Budish RA, et al. Upper extremity regional anesthesia techniques: A comprehensive review for clinical anesthesiologists. Best Practice \u0026amp; Research Clinical Anaesthesiology 2020;34:e13\u0026ndash;29. https://doi.org/10.1016/j.bpa.2019.07.005.\u003c/li\u003e\n\u003cli\u003eShimizu T, Ogawa T, Sano T, Hida T, Seo A, Abe N, et al. The efficacy of ultrasound-guided selective cutaneous nerve block during percutaneous transluminal angioplasty for radiocephalic arteriovenous fistulas. J Vasc Access 2025:11297298251360849. https://doi.org/10.1177/11297298251360849.\u003c/li\u003e\n\u003cli\u003eChin KJ, Lirk P, Hollmann MW, Schwarz SKW. Mechanisms of action of fascial plane blocks: a narrative review. Reg Anesth Pain Med 2021;46:618\u0026ndash;28. https://doi.org/10.1136/rapm-2020-102305.\u003c/li\u003e\n\u003cli\u003ePirri C, Torre DE, Stecco C. Fascial plane blocks: from microanatomy to clinical applications. Curr Opin Anaesthesiol 2024;37:526\u0026ndash;32. https://doi.org/10.1097/ACO.0000000000001416.\u003c/li\u003e\n\u003cli\u003eChin KJ, Versyck B, Elsharkawy H, Rojas Gomez MF, Sala-Blanch X, Reina MA. Anatomical basis of fascial plane blocks. Reg Anesth Pain Med 2021;46:581\u0026ndash;99. https://doi.org/10.1136/rapm-2021-102506.\u003c/li\u003e\n\u003cli\u003eRazaq S, Ricci V, Ricci C, \u0026Ouml;z\u0026ccedil;akar L. Ultrasound‐guided hydro‐dissection of the superficial fascia for cervical myofascial pain: a case series. J of Clinical Ultrasound 2025;53:940\u0026ndash;5. https://doi.org/10.1002/jcu.23947.\u003c/li\u003e\n\u003cli\u003eIm HS, Im JY, Kim KH, Kim DH, Park BK. Ultrasonographic study of the anatomical relationship between the lateral antebrachial cutaneous nerve and the cephalic vein. Ann Rehabil Med 2017;41:421. https://doi.org/10.5535/arm.2017.41.3.421.\u003c/li\u003e\n\u003cli\u003eKim KH, Byun EJ, Oh EH. Ultrasonographic findings of superficial radial nerve and cephalic vein. Ann Rehabil Med 2014;38:52. https://doi.org/10.5535/arm.2014.38.1.52.\u003c/li\u003e\n\u003cli\u003eLu M, Yang H, Xi W, Zhao X, Li H. Ultrasound-guided cradle-like infiltrative anesthesia for percutaneous transluminal angioplasty of stenotic autogenous arteriovenous hemodialysis access. Ann Vasc Surg 2022;83:135\u0026ndash;41. https://doi.org/10.1016/j.avsg.2021.12.012.\u003c/li\u003e\n\u003cli\u003eBorges \u0026Aacute;VRM, Souza SAL. Anatomy of the nerves, vessels, and muscular compartments of the forearm, as revealed by high-resolution ultrasound. Part 1: overall structure and forearm compartments. Radiol Bras 2021;54:388\u0026ndash;97. https://doi.org/10.1590/0100-3984.2021.0030.\u003c/li\u003e\n\u003cli\u003eChen L, Wang Q, Shi K, Liu F, Liu L, Ni J, et al. The effects of lidocaine used in sciatic nerve on the pharmacodynamics and pharmacokinetics of ropivacaine in sciatic nerve combined with lumbar plexus blockade: a double-blind, randomized study. Basic Clin Pharmacol Toxicol 2013;112:203\u0026ndash;8. https://doi.org/10.1111/bcpt.12008.\u003c/li\u003e\n\u003cli\u003eGraf BM. The cardiotoxicity of local anesthetics: the place of ropivacaine. Curr Top Med Chem 2001;1:207\u0026ndash;14. https://doi.org/10.2174/1568026013395164.\u003c/li\u003e\n\u003cli\u003eYamaguchi S, Kitamura J, Yamamoto K. [evaluation of motor block of the lower legs in continuous lumbar epidural infusion of ropivacaine]. Masui, Jpn J Anesthesiol 2012;61:583\u0026ndash;7.\u003c/li\u003e\n\u003cli\u003eFede C, Clair C, Pirri C, Petrelli L, Zhao X, Sun Y, et al. The human superficial fascia: a narrative review. Int J Mol Sci 2025;26:1289. https://doi.org/10.3390/ijms26031289.\u003c/li\u003e\n\u003cli\u003eFede C, Petrelli L, Pirri C, Neuhuber W, Tiengo C, Biz C, et al. Innervation of human superficial fascia. Front Neuroanat 2022;16:981426. https://doi.org/10.3389/fnana.2022.981426.\u003c/li\u003e\n\u003cli\u003eMarrone F, Pullano C, De Cassai A, Fusco P. Ultrasound-guided fascial plane blocks in chronic pain: a narrative review. J Anesth Analg Crit Care 2024;4:71. https://doi.org/10.1186/s44158-024-00205-y.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-medical-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejmr","sideBox":"Learn more about [European Journal of Medical Research](http://eurjmedres.biomedcentral.com)","snPcode":"40001","submissionUrl":"https://submission.nature.com/new-submission/40001/3","title":"European Journal of Medical Research","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"arteriovenous fistula, angioplasty, suprafascial plane block, brachial plexus block, ultrasound guidance, motor-sparing analgesia","lastPublishedDoi":"10.21203/rs.3.rs-8490214/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8490214/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e Balloon angioplasty for forearm arteriovenous fistula (AVF) often provokes substantial pain during inflation.\u003cbr\u003e\nObjective To compare an ultrasound-guided suprafascial plane block (SFPB) with brachial plexus block (BPB) during forearm AVF percutaneous transluminal angioplasty (PTA), focusing on analgesic effectiveness and safety.\u003cbr\u003e\n \u003cstrong\u003eMethods\u003c/strong\u003e Single-center, retrospective comparative study (January 1–December 31, 2025) of consecutive adults with forearm radiocephalic AVFs. SFPB targeted the superficial fascia–deep adipose tissue (SF–DAT) interface after sheath placement and guidewire traversal; BPB was completed before venipuncture. The primary endpoint was peak-inflation pain on the numeric rating scale (NRS, 0–10). Secondary outcomes included rescue analgesia, procedure time, block-related complications, and short-term patency.\u003cbr\u003e\n \u003cstrong\u003eResults\u003c/strong\u003e We analyzed SFPB (n=32) and BPB (n=35). The primary endpoint favored BPB (mean peak-inflation NRS 1.54 ± 0.74 vs 2.66 ± 0.85; mean difference −1.12, 95% CI −1.51 to −0.73; \u003cem\u003ep\u003c/em\u003e=0.0038). Importantly, SFPB still met the prespecified adequacy threshold in most cases (NRS ≤3 in 87.5%, 28/32) without rescue or conversion and with no transient motor block, whereas BPB produced universal transient motor block and hoarseness in 2 patients. Procedure time did not differ significantly (70.77 ± 37.51 vs 87.49 ± 36.21 min; \u003cem\u003ep\u003c/em\u003e=0.0613). One- and three-month primary patency was 100% in both groups.\u003cbr\u003e\n \u003cstrong\u003eConclusions\u003c/strong\u003e SFPB provided clinically adequate, motor-sparing analgesia that is compatible with outpatient workflow, while BPB achieved lower NRS at the expense of motor involvement. These findings support SFPB as a pragmatic, image-standardizable alternative; prospective trials are warranted.\u003c/p\u003e","manuscriptTitle":"Ultrasound-guided suprafascial plane block for forearm AVF angioplasty: a motor-sparing, image-standardizable alternative to brachial plexus block in a single-center retrospective comparison","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-12 16:00:35","doi":"10.21203/rs.3.rs-8490214/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-05-17T12:36:06+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"55795323439367842221478537029302454273","date":"2026-04-15T23:03:33+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-15T16:23:25+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"253291979403909278080010702666934516745","date":"2026-04-15T16:12:18+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-15T12:57:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"15330203187948428727510701789124403985","date":"2026-04-15T06:51:33+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"147101115563701182968690525068012472356","date":"2026-01-06T14:55:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"102552187596309710548249457175541734820","date":"2026-01-06T12:08:36+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-06T12:00:33+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-03T12:41:31+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-03T12:40:17+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Journal of Medical Research","date":"2025-12-31T13:36:23+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-medical-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejmr","sideBox":"Learn more about [European Journal of Medical Research](http://eurjmedres.biomedcentral.com)","snPcode":"40001","submissionUrl":"https://submission.nature.com/new-submission/40001/3","title":"European Journal of Medical Research","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"941ea89d-5e86-4ebb-adf7-6f09197f5c18","owner":[],"postedDate":"January 12th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Revision requested","date":"2026-05-17T12:36:06+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-05-17T12:39:14+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-12 16:00:35","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8490214","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8490214","identity":"rs-8490214","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}