A Prospective, Randomized Comparison Between Perivascular and Perineural Ultrasound-Guided Axillary Brachial Plexus Block
Bibliographic record
Abstract
BACKGROUND: This prospective, randomized, observer-blinded study compared perivascular (PV) and perineural (PN) ultrasound-guided axillary brachial plexus block (AXB) for upper extremity surgery. METHODS: Fifty patients were randomly allocated to receive a PV (n = 25) or PN (n = 25) ultrasound-guided AXB. The local anesthetic agent (lidocaine 1.5% with epinephrine 5 μg/mL) and total volume (32 mL) were identical in all subjects. For both groups, the musculocutaneous nerve was first located and then anesthetized using 8 mL. Subsequently, in the PV group, 24 mL was deposited dorsal to the axillary artery (6-o'clock position). In contrast, for the PN group, the median, ulnar, and radial nerves were individually anesthetized with volumes of 8 mL. 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 between the 2 groups in terms of success rate (92%-96%), total anesthesia-related time (27.1-29.0 min), and block-related pain scores. However, the PV technique required fewer needle passes (3.5 [SD, 1.0] vs 8.2 [SD, 2.2]; P = 0.000) as well as a shorter performance time (8.2 [SD, 2.3] vs 15.7 [SD, 3.2] min; P = 0.000) and was associated with a lower incidence of paresthesia (8 vs 52%; P = 0.001). In contrast, the PN technique resulted in a quicker onset time (13.8 [SD, 7.0] vs 18.9 [SD, 7.0] min; P = 0.021) and a decreased incidence of vascular puncture (0 vs 24%; P = 0.01). CONCLUSIONS: Perivascular and PN ultrasound-guided AXBs result in comparable success rates and total anesthesia-related times. Because of fewer needle passes and a shorter performance time, the PV technique provides a simple alternative for ultrasound-guided AXB.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.005 | 0.008 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".