Abstract 149: Double Sequential External Defibrillation in Refractory Ventricular Fibrillation: The Dose VF Pilot Randomized Controlled Trial
Bibliographic record
Abstract
Background: Despite significant advances in resuscitation efforts, there are some patients who remain in ventricular fibrillation (VF) after multiple defibrillation attempts during out-of-hospital cardiac arrest (OHCA). Double sequential external defibrillation (DSED) and vector change defibrillation (VC) have been proposed as alternate therapeutic strategies for OHCA patients in shock-refractory VF. Objective: To determine the feasibility, safety and sample size required for a larger, multicentered, 3-arm, cluster randomized controlled trial (RCT) with 2 crossovers comparing DSED or VC to standard defibrillation (control group) for OHCA patients presenting in shock-refractory VF. Methods: We conducted a pilot cluster randomized controlled trial with crossover including all consecutive treated adult OHCA patients who presented in VF and received a minimum of three successive shocks. In addition to standard cardiac arrest care, each EMS agency was randomly assigned to provide standard defibrillation (control), DSED, or VC, followed by crossover to an alternate defibrillation strategy after 6 months. Results: Prior to the launch of the trial, 2,500 paramedics received in-person training in the techniques of DSED and VC defibrillation using a combination of didactic, video and simulated scenarios. Between March 2018 and June 2019, 113 patients were enrolled in 4 Canadian EMS agencies, with zero missed cases. Monthly enrollment varied from 1 to 6 cases per agency. With respect to feasibility, 96% of cases were compliant with the study protocol, and only five (4.4%) cases received a defibrillation strategy that differed from the allocation schedule. There were no reported cases of defibrillator malfunction, no concerns expressed by paramedics, patients, families, or ED staff about the trial, and no reported cases of skin burns or difficulty with pad placement. Conclusions: Findings from our pilot implementation trial suggest the DOSE VF protocol is feasible and safe. The results of this internal pilot trial will allow us to calculate a sample size for a definitive multicenter cluster RCT with crossovers to determine if these alternate defibrillation strategies for OHCA shock refractory VF will impact patient-centered, clinical outcomes.
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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 | 0.003 | 0.005 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.002 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.013 | 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".