Abstract 106: Assessing Out-of-Hospital Cardiac Arrest Management With a New Automated External Defibrillator Algorithm: A Prospective Before-After Study on Ventricular Fibrillation Detection During Chest Compressions With a Shortened CPR Cycle

Abstract

Introduction: During out-of-hospital cardiac arrests (OHCA), AEDs analyze cardiac rhythm every 2 minutes with chest compressions (CC) having to be interrupted. Since 2021, the Paris Fire Brigade has used AEDs equipped with an "Analysis While Compressing" (AWC) module that enables an external electric shock (EES) to be delivered every minute if required. This new algorithm aligns AED analysis timing with potential VF recurrence but results in redistribution between CC time and analysis periods. We aimed to assess the CC fraction (CCF) in OHCA patients who received AWC and compared it with the CCF in 2017 patients who received a standard (STD) algorithm. Method: In this observational, prospective before-after study, we included adult non-traumatic OHCA patients with initial Ventricular Fibrillation (iVF) rescued by firefighters. Their AEDs provided STD algorithm in 2017 and AWC algorithm in 2022. All AED parameters were measured within 10 minutes of the initial shock. Primary outcome was the CCF, a criterion sensitive to algorithm modifications. Secondary outcomes were pre and post-shock pauses, and the percentage of time the cardiac rhythm was organized. We matched patients from both periods on four key covariates (sex, age, location, bystander status) using propensity score matching. The estimator for continuous variables was the median [interquartile range]. Results: We included 285 consecutive patients in each period. Most were men, 74% (212/285) in 2017 and 81% (231/285) in 2022; median ages were 58 [49-69] and 60 [51-72] years. After propensity score matching, CCF improved significantly with the AWC algorithm (77% [72%-80%]) vs. the STD algorithm (72% [67%-76%], p<0.01). Pre and post-shock pauses decreased from 19 [17-23] and 4.5 [3-6] to 11[9-16] and 3.8 [2-5] sec. in 2017 and 2022, respectively (p < 0.01). Delay from VF recurrence to the next shock decreased from 124 [92-135] sec. in 2017 to 60 [37-71] sec. in 2022 (p< 0.01). The time spent in an organized rhythm during the first ten min. of AED connection increased from 7 % [0-46] in 2017 to 14% [0-58] in 2022 (p< 0.01). Conclusion: AWC improved hands-on times, CCF, and time ratio spent in cardiac organized rhythm. Further analyses are underway to measure its impact on survival at hospital discharge.