Jean-Philippe Didon

Bench study of the accuracy of a commercial AED arrhythmia analysis algorithm in the presence of electromagnetic interferences.

This paper presents a bench study on a commercial automated external defibrillator (AED). The objective was to evaluate the performance of the defibrillation advisory system and its robustness against electromagnetic interferences (EMI) with central frequencies of 16.7, 50 and 60 Hz. The shock advisory system uses two 50 and 60 Hz band-pass filters, an adaptive filter to identify and suppress 16.7 Hz interference, and a software technique for arrhythmia analysis based on morphology and frequency ECG parameters. The testing process includes noise-free ECG strips from the internationally recognized MIT-VFDB ECG database that were superimposed with simulated EMI artifacts and supplied to the shock advisory system embedded in a real AED. Measurements under special consideration of the allowed variation of EMI frequency (15.7-17.4, 47-52, 58-62 Hz) and amplitude (1 and 8 mV) were performed to optimize external validity. The accuracy was reported using the American Heart Association (AHA) recommendations for arrhythmia analysis performance. In the case of artifact-free signals, the AHA performance goals were exceeded for both sensitivity and specificity: 99% for ventricular fibrillation (VF), 98% for rapid ventricular tachycardia (VT), 90% for slow VT, 100% for normal sinus rhythm, 100% for asystole and 99% for other non-shockable rhythms. In the presence of EMI, the specificity for some non-shockable rhythms (NSR, N) may be affected in some specific cases of a low signal-to-noise ratio and extreme frequencies, leading to a drop in the specificity with no more than 7% point. The specificity for asystole and the sensitivity for VF and rapid VT in the presence of any kind of 16.7, 50 or 60 Hz EMI simulated artifact were shown to reach the equivalence of sensitivity required for non-noisy signals. In conclusion, we proved that the shock advisory system working in a real AED operates accurately according to the AHA recommendations without artifacts and in the presence of EMI. The results may be affected for specificity in the case of a low signal-to-noise ratio or in some extreme frequency setting.

Pulse annotation of automatic external defibrillator recordings during out of hospital cardiac arrest

Obtaining information about the circulatory status of a patient during resuscitation is crucial. Attempts have been made toward integrating into automated external defibrillators a pulse detection algorithm based on the thoracic impedance signal. The lack of information about the hemodynamic status during out of hospital cardiac arrest (OHCA) has made the validation of such algorithms a challenging task. This study aims at proposing an annotation scheme for the assessment of pulse in OHCA. Being independent from the recording device, several databases could be annotated using the same protocol.

New Methods to Induce Localized Brain and General Hypothermia

Sudden Cardiac Death is a major concern in industrialized countries. In France, it is the cause of death of 40–60,000 cases per year. Despite efforts made over decades to promote cardiac resuscitation science, education, and the arrival of automatic external defibrillators, less than 50 % of cardiac arrest victims are likely to reach recovery of stable circulation and this percentage decreases even for patients who suffer a severe rhythm disorder that cannnot be defibrillated or patients living in rural areas. The vast majority of patients leaving alive from the hospital after outdoor cardiac arrest bear irreversible brain damage. However, the authors are convinced of the possibility of improving this situation through a better understanding of sudden death by screening high-risk individuals and a better organization of care through cooperation skills of the first responders. One of the most promising methods involves therapeutic hypothermia. This chapter will review the main historical steps and will propose a new method of brain protection by localized hypothermia produced by adiabatic carbon dioxide expansion, now under development on animal models and the first fortuitous clinical case.