Ultrasound with neurostimulation compared with ultrasound guidance alone for lumbar plexus block
Bibliographic record
Abstract
BACKGROUND: Ultrasound-guided lumbar plexus blocks usually require confirmatory neurostimulation. A simpler alternative is to inject local anaesthetic inside the posteromedial quadrant of the psoas muscle under ultrasound guidance. OBJECTIVE: We hypothesised that both techniques would result in similar total anaesthesia time, defined as the sum of performance and onset time. DESIGN: A randomised, observer-blinded, equivalence trial. SETTING: Ramathibodi Hospital and Maharaj Nakorn Chiang Mai Hospital (Thailand) from 12 May 2016 to 10 January 2017. PATIENTS: A total of 110 patients undergoing total hip or knee arthroplasty, who required lumbar plexus block for postoperative analgesia. INTERVENTION: In the combined ultrasonography-neurostimulation group, quadriceps-evoked motor response was sought at a current between 0.2 and 0.8 mA prior to local anaesthetic injection (30 ml of lidocaine 1% and levobupivacaine 0.25% with epinephrine 5 μg ml and 5 mg of dexamethasone). In the ultrasound guidance alone group, local anaesthetic was simply injected inside the posteromedial quadrant of the psoas muscle. MAIN OUTCOMES MEASURES: We measured the total anaesthesia time, the success rate (at 30 min), the number of needle passes, block-related pain, cumulative opioid consumption (at 24 h) and adverse events (vascular puncture, paraesthesia, local anaesthetic spread to the epidural space). The equivalence margin was 7.4 min. RESULTS: Compared with ultrasound guidance alone, combined ultrasonography-neurostimulation resulted in decreased mean (±SD) total anaesthesia time [15.3 (±6.5) vs. 20.1 (±9.0) min; mean difference, -4.8; 95% confidence interval, -8.1 to -1.9; P = 0.005] and mean (±SD) onset time [10.2 (±5.6) vs. 15.5 (±9.0) min; P = 0.004). No inter-group differences were observed in terms of success rate, performance time, number of needle passes, block-related pain, opioid consumption or adverse events. CONCLUSION: Although the ultrasonography-neurostimulation technique results in a shorter total anaesthesia time compared with ultrasound guidance alone, this difference falls within our accepted equivalence margin (±7.4 min). TRIAL REGISTRATION: www.clinicaltrials in the (Study ID: TCTR20160427003).
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".