Safe and effective concentration of ropivacaine in interscalene brachial plexus block for children aged 6 to 10 years: a sequential allocation study
Bibliographic record
Abstract
Abstract Objective To determine the median effective concentration (EC50) of ropivacaine at the volume of 0.5 mL/kg for ultrasound-guided interscalene brachial plexus block in children aged 6 to 10 years. Methods A prospective dose-finding trial was conducted based a sequential Dixon up-and-down allocation. We recruited children aged 6 to 10 years who were scheduled for unilateral surgery on upper extremity regions in our hospital from April to December 2022. All of them were subjected to general intravenous anaesthesia combined with ultrasound-guided interscalene brachial plexus block. The ropivacaine volume for each patient was 0.5 mL/kg. The concentration of 0.2% for the first patient, subsequent concentrations were adjusted based on the block effect of previous patient, increase or decrease by 0.02%. The trial was stopped when there were 7 turning points. Isotonic regression and Bootstrap were used to calculate the values of EC50 and 95% effective concentration (EC95), along with their 95% confidence intervals (CI). General data, incidence of adverse events, and score of postoperative pain were recorded. Results A total of 26 children aged 6 to 10 years were included. The EC50 of ultrasound-guided interscalene brachial plexus block was determined to be 0.091% (95%CI: 0.077%~0.105%), and the EC95 was estimated to be 0.117% (95%CI: 0.110%~0.118%). Successful blockade was achieved in 16 cases (61.5%), while 10 cases (38.5%) failed. No statistical differences existed between successful and failed cases regarding sex, age, body weight, surgical site, surgical laterality, operative time, or anesthesia duration. None of the patients experienced adverse events such as pneumothorax, vascular injury, or Horner’s syndrome, and the score of postoperative pain were all <6 by modified Children’s Hospital of Eastern Ontario Pain Scale. Conclusion In children aged 6 to 10 years, the EC50 of ropivacaine is 0.091% at a volume of 0.5 mL/kg for ultrasound-guided interscalene brachial plexus block, and this low dose of regional anesthetic can reduce the risks such as systemic toxicity and direct neurotoxicity.
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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 | 0.004 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.003 | 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".