Abstract 284: Looking Back to Glance Ahead: The Impact of Last Minute's Qrs Width & Frequency in Pulseless Electrical Activity

Abstract

Background: Observed heart rate and QRS-width during CPR in Pulseless Electrical Activity (PEA) develop differently in patients who gain ROSC compared to those who do not. In this study we investigated the impact of heart rate and QRS width on the transition from PEA to ROSC. Method: Defibrillator data from 293 episodes of cardiac arrest at two US and one Norwegian hospital were reviewed. The files contained ECG, impedance signal and compression depth. In total 178 episodes containing PEA intervals were included. Episodes with excessive ECG noise and signs of an active pacemaker were excluded. The files were processed in a MATLAB graphical application, and the clinical states were determined based on clinical documentation and the visual appearance of the ECG. ROSC was defined as an organized rhythm lasting longer than 1 minute without ongoing compressions. During pauses in compressions, heart rate and QRS-width was automatically measured and averaged over the preceding minute until current time and controlled and corrected manually. The results were analyzed using Aalen’s additive model for time-to-event data, using R version 3.6.3. Results: The average transition intensity, corresponding to the probability of gaining ROSC in one minute, was about 0.20 per min of CPR peaking at approximately 7 min. An increase in the average heart rate by 10/min increased the transition intensity by 0.03/min (p <0.01). Narrowing of the QRS in average by 100 milliseconds (ms) increased the transition intensity by 0.14/min (p <0.01). Our figure shows QRS width and heart rate for one patient with PEA approaching ROSC (gray area), with smoothed curves overlaid. Conclusion: Higher heart rates and narrower QRS complexes during PEA are strongly and significantly associated with a transition from PEA to ROSC. These changes could indicate whether a patient responds to ongoing CPR. In addition, there is a potential for predicting the immediate outcome based on these ECG characteristics.