P490Time boundaries of three-phase time-sensitive model for ventricular fibrillation cardiac arrest

Abstract

Abstract Funding Acknowledgements Japan Society for the Promotion of Science (KAKENHI Grant No. 18K09999) Background Recent clinical evidence has suggested that the pathophysiology of ventricular fibrillation (VF) cardiac arrest may consist of three time-sensitive phases, namely electrical, circulatory, and metabolic. According to this model of cardiopulmonary resuscitation (CPR), the optimal treatment of cardiac arrest is phase-specific. The potential survival benefit of bystander cardiopulmonary resuscitation (BCPR) depends in part on ischemic time (i.e., the collapse-to-shock interval), with the greatest benefit occurring during the circulatory (second) phase. However, the time boundaries between phases are not precisely defined in the current literature. Purpose The purpose of the present study was to determine the time boundaries of the three-phase time-sensitive model for VF cardiac arrest. Methods We reviewed 20,741 adult patients with initial VF after witnessed out-of-hospital cardiac arrest from a presumed cardiac origin who were included in the All-Japan Utstein-style registry from 2013 to 2017. We excluded patients who underwent bystander defibrillation prior to arrival of emergency medical services personnel. The study end point was 1-month neurologically intact survival (Cerebral Performance Category scale 1 or 2). Collapse-to-shock interval was defined as the time from collapse to first shock delivery by emergency medical services personnel. Patients were divided into two groups, BCPR (n = 11,606, 56.0%) and non-BCPR (n = 9135, 44.0%), according to whether they had received BCPR or not. Results The rate of 1-month neurologically intact survival in the BCPR group was significantly higher than that in the non-BCPR group (27.9% [3237/11,606] vs 17.9% [1632/9135], P < 0.0001; adjusted odds ratio [OR], 1.90; 95% confidence interval [CI], 1.75–2.07; P < 0.0001). Overall, increased collapse-to-shock interval was associated with significantly decreased adjusted odds of 1-month neurologically intact survival (adjusted OR for each 1-minute increase, 0.94; 95% CI, 0.93–0.95; P < 0.0001). In the BCPR group, the ranges of collapse-to-shock interval that were associated with increased adjusted 1-month neurologically intact survival were from 7 minutes (adjusted OR, 1.95; 95% CI, 1.44–2.63; P < 0.0001) to 17 minutes (adjusted OR, 2.82; 95% CI, 1.62–4.91; P = 0.0002) as compared with those in the non-BCPR group. However, the increase in neurologically intact survival of the BCPR group became statistically insignificant as compared with that of the non-BCPR group when the collapse-to-shock interval was outside these ranges. Conclusions The above-mentioned findings suggest that the time boundaries of the three-phase time-sensitive model for VF cardiac arrest may be as follows: electrical phase, from collapse to <7 minutes; circulatory phase, from 7 to 17 minutes; and metabolic phase, >17 minutes onward from collapse.