Lateral Versus Medial Needle Approach for Ultrasound-Guided Supraclavicular Block
Bibliographic record
Abstract
BACKGROUND: When performing a supraclavicular brachial plexus block (SCB) under ultrasound (US) guidance, the needle may approach the nerves in-plane with the US beam from 1 of 2 directions relative to the transducer, lateral-to-medial (lateral) or medial-to-lateral (medial). We aimed to compare the rates of sensory and motor block of the 4 major peripheral nerves of the upper extremity following a lateral or medial needle approach for US-guided SCB. METHODS: Eighty adult patients undergoing US-guided SCB for elective hand, wrist, forearm, or elbow procedures were randomized to either a lateral or medial needle approach. A 30-mL local anesthetic admixture (1:1 lidocaine 2%-bupivacaine 0.5% with 1:200,000 epinephrine) was injected to all patients. Sensory and motor function was assessed by a blinded observer at predetermined intervals. The primary outcome was the rate of sensory block in the distribution of the ulnar nerve measured 20 mins after block performance. RESULTS: Seventy-two patients were included in the final analysis. Patient characteristics were similar between groups. The rate of ulnar nerve sensory block at 20 mins was 63% in the lateral group and 62% in the medial group (P = 0.81). The rate of ulnar nerve sensory block at 30 mins increased to 89% in the lateral and 84% in the medial group (P = 0.96). The rates of both sensory and motor block in the distributions of the median, radial, and musculocutaneous nerves were high and did not differ between groups at any measured time interval. The block performance time and the postoperative pain scores were similar between the 2 groups. Complications were minor and transient and did not differ between groups. CONCLUSIONS: The rates of sensory and motor block of all 4 major peripheral nerves of the upper extremity did not differ at any time following a lateral compared with medial needle approach for US-guided SCB. Regardless of needle approach, the rate of ulnar nerve sensory block was less compared with the other peripheral nerves following US-guided SCB.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 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".