Perineural Dexmedetomidine Is More Effective Than Clonidine When Added to Local Anesthetic for Supraclavicular Brachial Plexus Block: A Systematic Review and Meta-analysis
Bibliographic record
Abstract
BACKGROUND: Clonidine, an α-2 agonist, has long been used as a local anesthetic adjunct with proven efficacy to prolong peripheral nerve block duration. Dexmedetomidine, a newer α-2 agonist, has a more favorable pharmacodynamic and safety profile; however, data comparing its efficacy as an adjunct to that of clonidine are inconsistent. We sought to compare the clinical efficacy of these 2 α-2 agonists by examining their effects on peripheral nerve block characteristics for upper extremity surgery. METHODS: A preliminary search found that the overwhelming majority of randomized controlled trials comparing perineural dexmedetomidine to clonidine for upper extremity surgery were in the setting of supraclavicular brachial plexus block (SCB). Therefore, we performed a systematic review and meta-analysis of randomized controlled trials comparing dexmedetomidine with clonidine as perineural adjuncts to single-injection SCB. Sensory and motor block duration and onset, analgesic duration, α-2 agonist side effects, and block complications were analyzed. Sensory block duration was designated as a primary outcome. Data were combined using random-effects modeling, and ratio-of-means was used to analyze the results. RESULTS: A total of 868 patients from 14 clinical studies were included in the analysis. Compared with clonidine, dexmedetomidine prolonged the duration (ratio of means [95% confidence interval {CI}]) of sensory block by an estimate of 1.2 (1.2-1.3; P< .00001). It also prolonged the duration (ratio of means [99% CI]) of motor block by an estimate of 1.2 (1.1-1.3; P < .00001), and analgesia by an estimate of 1.2 (1.1-1.3; P < .00001). It also hastened the onset of sensory block by an estimate of 0.9 (0.8-1.0; P < .00001) and motor block by an estimate of 0.9 (0.9-1.0; P = .002). Dexmedetomidine was associated with an increased odds ratio (99% CI) of transient bradycardia by an estimate of 7.4 (1.3-40.8; P = .003) and postoperative sedation by an estimate of 11.8 (1.9-73.6; P = .0005). There were no differences in other α-2 agonist-related side effects or block-related complications. CONCLUSIONS: Compared with clonidine as a local anesthetic adjunct for single-injection SCB, perineural dexmedetomidine enhances sensory, motor, and analgesic block characteristics. These benefits should be weighed against the increased risk of transient bradycardia.
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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 | 0.009 | 0.021 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.017 | 0.031 |
| Bibliometrics | 0.005 | 0.007 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 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".