Abstract 97: The Overlap in Frequency Spans of Ventricular Fibrillation and Chest Compression in Cardiac Arrest Patients
Background In treating sudden cardiac arrest (SCA) patients, automatic external defibrillators automatically analyze the ECG rhythm to determine if defibrillation is necessary. Currently, this analysis must be done during hands-off period because the electrical artifact induced by chest compression (CC) makes the analysis unreliable. It is desired to analyze the ECG rhythm during CPR to minimize the hands-off period, and hence, improve CPR success. Simple filtering of CC artifact would work only if there is no significant overlap between frequency spans of CC and ventricular fibrillation (VF); otherwise, it would distort the ECG.
Objective To investigate the overlap between CC and VF frequency spans.
Methods ECG recordings from 170 SCA adult patients with VF rhythm were used. These cases were a subset of a larger database collected for a clinical study in 6 ambulances in 3 European regions using Laerdal HeartStart 4000 defibrillators. The defibrillator had an extra chest pad with an accelerometer and a pressure sensor to record the CC signal. The VF and CC frequency spans were calculated by frequency-domain analysis of the signals.
Results The figure below demonstrates the frequency spans of VF and CC in patients with VF rhythm going under CPR. The plots are normalized and also include the higher harmonics. A significant overlap is observed at the range of 80 to 140 compressions-per-minute.
Conclusion The significant overlap in frequency spans of VF and CC makes it challenging to filter the CC artifact without removing parts of VF information and hence distorting the ECG signal. Therefore, techniques for analyzing ECG during CPR should be smarter than merely filtering the CC artifact.
- Cardiac arrest
- Ventricular fibrillation
- Cardiopulmonary resuscitation
- Sudden cardiac death
- © 2012 by American Heart Association, Inc.