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 distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.005 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".