Escalating vs Fixed Energy Defibrillation in Out-of-Hospital Cardiac Arrest Ventricular Fibrillation.

Importance: There is limited evidence on whether higher-energy defibrillation is preferred in patients experiencing out-of-hospital cardiac arrest (OHCA) with shockable rhythms. Objective: To investigate the optimal energy regimen for initial and subsequent defibrillation delivered by biphasic waveform automated external defibrillators (AEDs) in OHCA ventricular fibrillation (VF). Design, Setting, and Participants: This cohort study was conducted in 48 cities across China, from 2017 to 2023, among 342 patients with OHCA who experienced at least 1 shock. Exposures: Escalating higher-energy (200-300-360 J) defibrillation or fixed low-energy (200-200-200 J) defibrillation according to the AED program available for use. Main Outcome and Measures: Sustained and transient termination of VF and establishment of an organized rhythm after defibrillations were the main clinical outcomes. Results: A total of 342 patients with OHCA were included (mean [SD] age, 57.2 [20.6] years; 273 male [79.8%]) with 782 VF defibrillations; 218 patients (63.8%) with a total of 480 instances (61.4%) of VF rhythm received AED with escalating higher-energy regimens. Most VF episodes were effectively terminated transiently at the first shock (200 J in both groups) (94% in the escalating higher-energy group vs 93% in the fixed lower-energy group; P = .64), but only half remained terminated until the next rhythm analysis (49% vs 47%; P = .68). Comparatively, VF that received escalating higher-energy regimens were more likely to establish sustained organized rhythm (34% vs 25%; P = .008; absolute difference, 9% [95% CI, 2% to 16%]). In refractory VF rhythms, the percentage of cases where sustained organized rhythms were established was significantly greater in escalating higher-energy regimens after second shocks and above (24% vs 13%; P = .008; absolute difference, 11% [95% CI, 3% to 19%]) and third shocks and above (35% vs 18%; P = .003; absolute difference 17% [95% CI, 5% to 27%]). Conclusions and Relevance: In this retrospective cohort study of patients experiencing OHCA-VF, both the escalating higher-energy (200-300-360 J) regimen and the fixed low-energy (200-200-200 J) regimen were effective for transient VF termination at first shock, whereas the escalating higher-energy regimens were more likely to maintain termination and restore an organized rhythm. Higher-energy regimens were associated with better outcomes after all shocks, especially in patients with refractory VF.