Comparison of a Single- or Double-Injection Technique for Ultrasound-Guided Supraclavicular Block
Bibliographic record
Abstract
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.
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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 | 0.003 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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 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".