Abstract 157: Multicenter Evaluation of Etiology and Observed Transition Intensities Between Pulseless Electrical Activity and Return of Spontaneous Circulation
Background: Cardiac arrest presents with one of three clinical states; Cardiac standstill (asystole), Pulseless Electrical Activity (PEA), or ventricular fibrillation/tachycardia (VF/VT). PEA results from multiple etiologies and accounts for most in-hospital cardiac arrests. We quantified the dynamic nature of transitions in and out of PEA, in terms of hospital sites and presumed etiology. Methods: We analyzed 538 episodes of cardiac arrest at one Norwegian hospital and three U.S. hospitals. ECG, chest compressions and ventilations were recorded by defibrillators during CPR. Each event was assessed using a graphical application. We quantified the transition intensity, i.e. the immediate probability of a transition given the current state, between PEA and ROSC using Aalen’s additive model for time-to-event data. Results: The overall transition intensity from PEA to ROSC was about 0.10 min -1 , so an average patient in PEA has about 10 % chance to gain ROSC the following 1 minute. The intensity peaked at 7 minutes of CPR (Figure), with some heterogeneity between hospitals (0.07 to 0.11 min -1 ). The reverse transition intensity from ROSC to PEA was rather constant at 0.10 min -1 (range 0.05-0.11). Information regarding assumed cardiac or non-cardiac etiology was available in 208 episodes (123 cardiac). Patients with a cardiac etiology had a marginally smaller (-0.03 min -1 ) chance of making the transition from PEA to ROSC (p=0.049), but etiology did not impact on the ROSC to PEA transition (p=0.39). Discussion: For transitions between PEA and ROSC we observed an overall intensity of 0.1 min -1 , with some hospital heterogeneity. This may be due to heterogeneity in the underlying patient populations. We found the probability of transitioning from PEA to ROSC to increase from the start event recording until an average peak intensity at 7 minutes. This information may increase the clinicians’ understanding of the process from PEA to ROSC.