Amplitude spectrum area to predict true shock-refractory ventricular fibrillation during basic life support-treated out-of-hospital cardiac arrest
Bibliographic record
Abstract
AIM: Refractory ventricular fibrillation (VF) is associated with decreased survival. Guideline definition of refractory VF, i.e. a VF persisting after 3 shocks, includes cases of true shock-refractory VF or recurrent VF with transient defibrillation response. Predicting true shock-refractory VF before repeated shock failure could prioritize targeted interventions to improve out-of-hospital cardiac arrest (OHCA) outcomes. We hypothesized that amplitude spectrum area (AMSA) may predict cases of true refractory VF. METHODS: ECGs recorded by automated external defibrillators were obtained from OHCAs in 8 cities in Italy. A 2-second VF window before each defibrillation was analyzed to calculate Amplitude Spectrum Area (AMSA). Defibrillation success was defined by occurrence of a perfusing rhythm, while refractory VF was defined as: "pragmatic-refractory" (based on guideline definition); or within this category, as "True shock-refractory", if VF continuously persisted over the period needed to deliver the first 3 shocks; or "refractory-recurrent", if VF recurred after any of the first three shocks transiently terminated VF. RESULTS: 1646 OHCAs with shockable presenting rhythm were included, 360 (22 %) of whom met the definition of pragmatic-refractory VF. Among the 360 cases of pragmatic-refractory VF, 18 % were true shock-refractory and 82 % were refractory-recurrent VF. AMSA was significantly lower in true shock-refractory VF than in refractory-recurrent VF. A lower first AMSA was associated with occurrence of true shock-refractory VF (aOR:0.81; 95 %CI: 0.73-0.88; p < 0.0001). CONCLUSIONS: Lower AMSA is associated with true shock-refractory VF, a subtype associated with persistent defibrillation failure and worse long-term survival. Identifying different VF subtypes early may help guide advanced resuscitation strategies in OHCA.
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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 | 0.000 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".