Abstract 253: Trajectory of Ventricular Fibrillation Prognostic Status During Cardiopulmonary Resuscitation

Abstract

Background: Resuscitation from out-of-hospital cardiac arrest (OHCA) due to ventricular fibrillation (VF) typically involves continuous CPR cycles interrupted every 2 minutes for rhythm analysis and potential defibrillation. Quantitative measures of the VF ECG waveform have been proposed to guide therapy for VF arrest because they are associated with myocardial energetics, are dynamic over the course of resuscitation, and predict outcome. However, while VF waveform measures have until recently have required CPR interruption to accurately gauge prognostic status, CPR interruptions are associated with a lower chance of survival. We used a novel waveform measure previously-validated during active CPR to estimate the course of VF status through the 2-minute CPR cycle between consecutive shocks. Methods: We conducted an observational study of patients with VF OHCA who experienced recurrent VF for at least 90 seconds following initial shock. We used the continuous defibrillator ECG to calculate the VF waveform measure as a function of predicted probability of survival-with-intact-neurologic-status at 1-s intervals over the course of resuscitation between shocks. Results: We collected 499 VF ECG segments (≥90 seconds) during CPR from 313 patients. The trajectory of the average prognostic VF measure had a 3-phase time-dependent pattern (Fig. 1). During CPR, the slope of the measure decreased during the initial 25 s of VF (slope = -12%/min) and was relatively flat during the subsequent 65-s interval of VF (slope = +1%/min). Furthermore, slope decreased sharply following the cessation of CPR for rhythm analysis, charge, and shock (slope = -23%/min). Conclusion: On average, a novel VF waveform measure assessed during the scheduled cycle of CPR and rhythm analysis between consecutive shocks was characterized by a period of decline, stabilization, and then decline. Whether these changes in VF status can be used to improve care for individual patients is uncertain.