Abstract 12825: Feasibility of Amplitude Spectrum Area Estimation in Ventilation Pauses During Cardiopulmonary Resuscitation

Abstract

Introduction: Amplitude spectral area (AMSA) calculated from ventricular fibrillation (VF) waveform not only predicts defibrillation outcome, but may also reflect effectiveness of chest compressions. However, reliable VF waveform analysis usually requires rescuers to stop compressions. In the present study, we investigated whether AMSA could be accurately estimated in ventilation pauses during cardiopulmonary resuscitation (CPR). Methods: A total of 40 out-of-hospital cardiac arrest patients with VF as the initial rhythm were included in this study. All patients received resuscitation with a 30:2 compressions to ventilation ratio. ECG data and chest compression waveforms before first defibrillation were extracted. Each episode included at least one full resuscitation cycle consisting of 30 compressions followed by a ventilation pause, further compressions, and a pre-shock pause with artifact-free VF signal. AMSA was continuously calculated using a sliding window of 2 seconds duration with sliding step size of 1 sampling point. Ventilation pauses were identified by the chest compression waveforms. Mean AMSA value during chest compression (AMSA_c) and minimal AMSA value during ventilation pause (AMSA_p) were compared with the AMSA value measured in noise-free VF (AMSA_nf) during the pre-shock pause. Results: Twenty patients received mechanical CPR and other 20 patients received manual chest compressions. The ventilation pause was 3.19±0.62 sec for mechanical CPR and 5.96±2.06 for manual CPR. AMSA_c was significantly higher than AMSA_p (32.4±30.0 mVHz vs. 6.6±3.9 mVHz, p <0.01) and AMSA_nf (32.4±30.0 mVHz vs. 6.0±3.5 mVHz, p <0.01). As shown in Figure 1, AMSA_nf was strongly correlated with AMSA_p (r=0.90, p <0.01) but not with AMSA_c (r=0.50, p =0.11). Conclusions: AMSA could be reliably determined in ventilation pauses during CPR but not during chest compressions.