Impact of an extrafascial versus intrafascial injection for supraclavicular brachial plexus block on respiratory function: a randomized, controlled, double-blind trial
Bibliographic record
Abstract
INTRODUCTION: Hemidiaphragmatic paresis after ultrasound-guided supraclavicular brachial plexus block is reported to occur in up to 67% of patients. We tested the hypothesis that an injection outside the brachial plexus sheath reduces the incidence of hemidiaphragmatic paresis compared with an intrafascial injection while providing similar analgesia. METHODS: Fifty American Society of Anesthesiologists I-III patients scheduled for elective upper limb surgery received a supraclavicular brachial plexus block using 30 mL of 1:1 mixture of mepivacaine 1% and ropivacaine 0.5%. The block procedures were randomized to position the needle tip either within the brachial plexus after piercing the sheath (intrafascial injection) or outside the brachial plexus sheath (extrafascial injection). The primary outcome was the incidence of hemidiaphragmatic paresis 30 min after the injection, measured by M-mode ultrasonography. Additional outcomes included time to surgery readiness, and resting and dynamic pain scores at 24 hours postoperatively (Numeric Rating Scale, 0-10). RESULTS: The incidence of hemidiaphragmatic paresis 30 min after the injection was 9% (95% CI 1% to 29%) and 0% (95% CI 0% to 15%) in the intrafascial and extrafascial groups respectively (p=0.14). Extrafascial injection was associated with a longer time to surgery readiness (intrafascial: 18 min (95% CI: 16 to 21 min); extrafascial: 37 min (95% CI: 31 to 42 min); p<0.001). At 24 hours, resting and dynamic pain scores were similar between groups. DISCUSSION: Ultrasound-guided supraclavicular brachial plexus block with an extrafascial injection does not reduce the incidence of hemidiaphragmatic paresis although it provides similar analgesia, when compared with an intrafascial injection. The longer time to surgery readiness is less compatible with contemporary operating theater efficiency requirements. TRIAL REGISTRATION NUMBER: NCT03957772.
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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 | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.005 | 0.002 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.008 | 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".