Abstract 253: Method for Minimal Delay Triggering of VF Detection During Cardio Pulmonary Resuscitation
Background: The detection of ventricular fibrillation (VF) by Automated External Defibrillators (AED) during cardiopulmonary resuscitation (CPR) is influenced by artifacts from chest compressions (CC). CC-free ECG signals for accurate VF analysis are scarce and found mostly during the short-time ‘hands-off’ intervals. Therefore, an appropriate detection of the end of CC (EoCC) is important for immediate triggering of the VF analysis. The aim of this study is to present the accuracy of that part of a shock advisory system (SAS) which is designed for triggering of CC-free VF detection process at minimal delay.
Method: Recordings of 40 OHCA interventions with AEDs (FredEasy, Schiller Medical SAS, France) are retrospectively processed. 1400 EoCC events are identified by manual annotation of the time when the CC artifacts in both ECG and impedance (DZ) channels disappear after periods with CC contamination. The EoCC detections are obtained by running SAS process based on DZ channel analysis by measurements of waves and rates of CC artifacts.
Results: Since there is no standard for reporting the accuracy of EoCC detection algorithms, we evaluate the percentage of the EoCC detections provided within 4 confidence delays around the EoCC annotation. With the 565 EoCCs from the learning database, the algorithm reaches an accuracy of 79.3%, 86.5%, 92.2%, 95.6% for 0.3s, 0.5s, 0.7s, 1s delays respectively. A validation performed on 835 different EoCCs from a test database showed no significantly different results.
Conclusion: To our knowledge this is the first study reporting the minimal delay at which VF detection analysis can be triggered after EoCC. The collection of CC-free ECG is crucial for the VF detection accuracy, therefore the assessment of the triggering method guarantees a certain ECG quality. Our observations over EoCC events in real OHCA performed by different rescuers show different waveforms and durations of the DZ channel transition process just after EoCC. The SAS provides a minimal delay of 0.3s in about 79% of EoCCs and 90% of EoCCs are detected within a delay of 0.7s.
- © 2010 by American Heart Association, Inc.