Minimum Effective Volume of Local Anesthetic for Ultrasound-Guided Supraclavicular Brachial Plexus Block
Bibliographic record
Abstract
BACKGROUND AND OBJECTIVES: The aim of this study was to determine the minimum effective anesthetic volume required to produce an effective supraclavicular block for surgical anesthesia using an ultrasound (US)-guided technique. METHODS: Twenty-one adults undergoing elective upper limb surgery received a US-guided supraclavicular block. The initial volume of local anesthetic (LA; 50:50 mixture of lidocaine 2% and bupivacaine 0.5% with epinephrine) injected was 30 mL, which was subsequently varied by 5 mL for each consecutive patient according to the response of the previous patient. The minimum effective anesthetic volume in 50% of patients was determined using the Dixon and Massey up-and-down method. The effective volume in 95% of patients (ED95) was calculated using probit transformation and logistic regression. RESULTS: The minimum effective anesthetic volume in 50% and calculated effective volume in 95% of patients were 23 mL (95% confidence interval, 13-39 mL) and 42 mL (95% confidence interval, 19-65 mL), respectively. Seven patients received supplemental LA, with no patient requiring a general anesthetic. CONCLUSION: In this study, the minimum volume required for US-guided supraclavicular block in 50% of patients was 23 mL, and in 95% of patients was 42 mL. Under the present study conditions, the calculated volume of LA required for US-guided supraclavicular block does not seem to differ from the conventionally recommended volume required for supraclavicular blocks using non-US-based nerve localization techniques.
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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 | 0.003 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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".