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.