Experimental paperRhythm discrimination during uninterrupted CPR using motion artifact reduction system☆
Introduction
Chest compressions represent an essential component of cardiopulmonary resuscitation (CPR), but the compressions often render the ECG uninterpretable due to associated motion artifact. Since management decisions regarding administration of medications and application of defibrillation shocks are predicated by the electrocardiographic rhythm, chest compressions are interrupted during CPR, often repeatedly and for many seconds at a time, to allow for acquisition of uncorrupted ECGs. However, interruptions in chest compressions reduce the hemodynamic benefit and likelihood of survival from CPR.1, 2 Interruption of chest compressions is also required when using automatic external defibrillators (AEDs). These devices instruct the operator to discontinue compressions so that the ECG can be analyzed, delaying appropriate therapy and limiting the time for chest compressions to roughly 40% of CPR time.3, 4, 5, 6
We hypothesized that artifacts in the ECG related to chest compressions could be removed using adaptive noise cancellation techniques, enabling automated rhythm discrimination by standard AED algorithms, during uninterrupted CPR. We tested this hypothesis by processing in real time the ECG obtained from anesthetized swine undergoing CPR using a load-distributing band to compress the anterior chest, and feeding the filtered ECG to three different commercial AED or equivalent devices for rhythm analysis. The unfiltered ECG was fed simultaneously to three identical AED devices to serve as control.
Section snippets
Animal preparation
Thirteen swine (20–25 kg) of either sex received ketamine 22 mg/kg intramuscularly. After tracheal intubation and mechanical ventilation, anesthesia was maintained with isoflurane (1–2.5%) in 100% oxygen, and minute ventilation was titrated to achieve an end-tidal CO2 between 35 and 45 mmHg. From a jugular cutdown, a pacing catheter was placed into the right ventricle. The animals were prepared by shaving and scrubbing the chest with alcohol. Adult defibrillation pads (Quick Combo, Medtronic) were
Recorded waveforms
Examples of measured and calculated waveforms obtained during NSR and VF are shown in Figure 3, Figure 4, respectively. In these examples, the instantaneous force signal measured from the automatic compression device and the raw surface ECG are shown in the top two traces. The part of the raw ECG signal that the MARS system determined to represent artifact, based on correlation with the force signal, is shown in the third tracing, and the predicted “true” ECG, calculated as the difference
Main findings
The main findings of this study are that (1) motion artifacts in the ECG introduced by automated CPR can be greatly suppressed using adaptive noise cancellation when a reference signal related to compression force is available, (2) MARS allows for appropriate automated recognition of VF during uninterrupted CPR, while this is rarely possible based on the raw ECG, (3) MARS does not introduce artifacts that would lead to misclassification of NSR or asystole during CPR, and (4) MARS does not
Conclusion
Motion artifacts in the ECG caused by chest compressions during automated CPR can be effectively suppressed using adaptive noise cancellation techniques. With this strategy, automated arrhythmia detection is feasible during uninterrupted CPR. Clinical testing of this system should be pursued to determine whether it leads to improved survival with CPR.
Conflict of interest
Drs. Berger and Halperin are paid consultants of ZOLL Medical Corp. The terms of this arrangement are being managed by the Johns Hopkins University in accordance with its conflict of interest policies. Mr. Palazzolo is an employee of ZOLL Medical Corp.
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Inaccurate treatment decisions of automated external defibrillators used by emergency medical services personnel: Incidence, cause and impact on outcome
2015, ResuscitationCitation Excerpt :This is a well-known weakness for most AED brands dealt with by “stand clear” voice prompts.8–11 As the interruption of chest compressions immediately before shock delivery has been shown to correlate with defibrillation failure, much research in AEDs is being conducted to allow chest compressions during the ECG analysis and charging process.16–18 Until such new technology is integrated in AEDs, (re)training should focus on “hands off” during ECG analysis and on respecting the “stand clear” prompts.
A review of chest compression interruptions during out-of-hospital cardiac arrest and strategies for the future
2013, Journal of Emergency MedicinePerhaps crying "clear" should be left to the TV actors?
2013, Resuscitation
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A Spanish translated version of the summary of this article appears as Appendix in the final online version at 10.1016/j.resuscitation.2007.03.007.