Predictors of Technical Difficulty in Emergency Department Ultrasound-Guided Nerve Blocks: A Multicenter NURVE Registry Analysis
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Updated: Nov 2, 2026
Spinal Sonography for Ultrasound-Guided Lumbar Neuraxial Anesthesia
Published on: January 31, 2025
Lachlan Driver1, Leland Perice1, Tasneem Zaihra Rizvi2
1Department of Emergency Medicine, Brown Emergency Medicine, Providence, Rhode Island.
Background:
Ultrasound-guided nerve blocks (UGNBs) are increasingly used in emergency departments (EDs), but factors associated with technical difficulty remain poorly characterized.
Objectives:
To characterize the frequency of technical difficulty during ED UGNBs and explore patient-, provider-, and block-level factors associated with difficult procedures.
Methods:
We performed a retrospective analysis of the multicenter National Ultrasound-guided neRVE (NURVE) Registry, including UGNBs performed at 11 U.S. EDs from January 2022 through December 2023. This interval was selected to capture the complete initial two-year period of NURVE Registry data collection. Technical difficulty was defined by operator self-report using a standardized registry question. Mixed-effects logistic regression with institution as a random intercept was used to evaluate factors associated with technical difficulty.
Results:
Among 1725 UGNBs included in the analysis, 82 (4.8%) were reported as technically difficult. In unadjusted analyses, technical difficulty was more common among patients with obesity and differed by block group. In mixed-effects regression, body mass index (BMI) ≥ 30 kg/m² was independently associated with increased odds of technical difficulty compared with BMI 18.5-24.9 kg/m² (odds ratio [OR] 2.94, 95% confidence intervals [CI] 1.58-5.47). Compared with fascia iliaca/femoral region blocks, truncal plane blocks (OR 0.20, 95% CI 0.05-0.87), distal upper-extremity blocks (OR 0.12, 95% CI 0.02-0.94), and distal lower-extremity blocks (OR 0.32, 95% CI 0.10-0.99) were associated with lower odds of technical difficulty. Provider role and prior procedural experience were not significantly associated with difficulty in unadjusted analyses.
Conclusions:
Technical difficulty during ED UGNBs was uncommon. Obesity was the most consistent predictor of procedural difficulty, while block-group associations were more modest and influenced by site-level factors. These findings may help inform procedural planning and UGNB training initiatives.
