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Krasteva V.,Bulgarian Academy of Science | Jekova I.,Bulgarian Academy of Science | Dotsinsky I.,Bulgarian Academy of Science | Didon J.-P.,Schiller Medical SAS
Annals of Biomedical Engineering | Year: 2010

Minimum "hands-off" intervals during cardiopulmonary resuscitation (CPR) are required to improve the success rate of defibrillation. In support of such life-saving practice, a shock advisory system (SAS) for automatic analysis of the electrocardiogram (ECG) contaminated by chest compression (CC) artefacts is presented. Ease of use for the automated external defibrillators (AEDs) is aimed and therefore only processing of ECG from usual defibrillation pads is required. The proposed SAS relies on assessment of outstanding components of ECG rhythms and CC artefacts in the time and frequency domain. For this purpose, three criteria are introduced to derive quantitative measures of band-pass filtered CC-contaminated ECGs, combined with three more criteria for frequency-band evaluation of reconstructed ECGs (rECG). The rECGs are derived by specific techniques for CC waves similarity assessment and are reproducing to some extent the underlying ECG rhythms. The rhythm classifier embedded in SAS takes a probabilistic decision designed by statistics on the training dataset. Both training and testing are fully performed on real CC-contaminated strips of 10 s extracted from human ECGs of out-of-hospital cardiac arrest interventions. The testing is done on 172 shockable strips (ventricular fibrillations VF), 371 non-shockable strips (NR) and 330 asystoles (ASYS). The achieved sensitivity of 90.1% meets the AHA performance goal for noise-free VF (>90%). The specificity of 88.5% for NR and 83.3% for ASYS are comparable or even better than accuracy reported in literature. It is important to note that, the aim of this SAS is not to recommend shock delivery but to advice the rescuers to "Continue CPR" or to "Stop CPR and Prepare for Shock" thus minimizing "hands-off" intervals. © 2010 Biomedical Engineering Society. Source


Krasteva V.,Bulgarian Academy of Science | Jekova I.,Bulgarian Academy of Science | Didon J.-P.,Schiller Medical SAS
Physiological Measurement | Year: 2011

This study aims to contribute to the scarce data available about the abilities of untrained lay persons to perform hands-only cardio-pulmonary resuscitation (CPR) on a manikin and the improvement of their skills during training with an autonomous CPR feedback device. The study focuses on the following questions: (i) Is there a need for such a CPR training device? (ii) How adequate are the embedded visual feedback and audio guidance for training of lay persons who learn and correct themselves in real time without instructor guidance? (iii) What is the achieved effect of only 3 min of training? This is a prospective study in which 63 lay persons (volunteers) received a debriefing to basic life support and then performed two consecutive 3 min trials of hands-only CPR on a manikin. The pre-training skills of the lay persons were tested in trial 1. The training process with audio guidance and visual feedback from a cardio compression control device (CC-Device) was recorded in trial 2. After initial debriefing for correct chest compressions (CC) with rate 85-115 min -1, depth 3.8-5.4 cm and complete recoil, in trial 1 the lay persons were able to perform CC without feedback at mean rate 95.9 18.9 min -1, mean depth 4.13 1.5 cm, with low proportions of 'correct depth', 'correct rate' and 'correct recoil' at 33%, 43%, 87%, resulting in the scarce proportion of 14% for compressions, which simultaneously fulfill the three quality criteria ('correct all'). In trial 2, the training process by the CC-Device was established by the significant improvement of the CC skills until the 60th second of training, when 'correct depth', 'correct rate' and 'correct recoil' attained the plateau of the highest quality at 82%, 90%, 96%, respectively, resulting in 73% 'correct all' compressions within 3 min of training. The training was associated with reduced variance of the mean rate 102.4 4.7 min -1 and mean depth 4.3 0.4 cm, indicating a steady CC performance achieved among all trained participants. Multivariable linear regression showed that the compression depth, rate and complete chest recoil did not strongly depend on lay person age, gender, height, weight in pre-training and training stage (correlation coefficient below 0.54). The study confirmed the need for developing CPR abilities in untrained lay persons via training by real-time feedback from the instructor or CC-Device. The CC-Device embedded feedback was shown to be comprehensible and easy to be followed and interpreted. The high quality of the CC-Device-assisted training process of lay persons was confirmed. Thus learning or refresher courses in basic life support could be organized for more people trained at the same time with fewer instructors needed only for the initial debriefing and presentation of the CC-Device. © 2011 Institute of Physics and Engineering in Medicine. Source


Didon J.-P.,Schiller Medical SAS | Jekova I.,Bulgarian Academy of Science | Krasteva V.,Bulgarian Academy of Science
Computing in Cardiology | Year: 2010

This study aims at validation of the specificity (Sp) of a shock advisory system (SAS) in automatic external defibrillators (AED) with non-shockable pediatric ECGs. Own pediatric ECG database is collected including lead II holter recordings from 46 children - healthy and cardiac patients. A number of 10301 ten-second samples of non-shockable (N) rhythms are analysed. Adult ECG database (MIT-vfdb) is used to show the reference SAS criteria values for N(>18) and shockable S(>18) rhythms. Specific ECG criteria of an AED SAS are evaluated: heart rate, slope uniformity of positive vs. negative peaks, deflections from signal extrema and signal mean in a narrow frequency band for QRS complexes enhancement. Pediatric N rhythms, age: (1-4), (5-8), (9-12) vs. adult N(>18) show significant differences in all criteria, shifting in beneficial direction further away from S(>18) when combined criteria are used. The SAS validation for N(1-4), N(5-8), N(9-12) present respectively Sp=100%, 99.8%, 100%, higher than N(>18) with 99.6%. Source


The invention relates to a defibrillator with integrated means for chest compression feedback. The defibrillator is shaped and sized such as to be directly placeable on the patients chest.


Oster J.,Nancy University Hospital Center | Pietquin O.,Nancy University Hospital Center | Pietquin O.,Supelec | Kraemer M.,Schiller Medical SAS | Felblinger J.,Nancy University Hospital Center
ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings | Year: 2010

Electrocardiogram (ECG) is required during Magnetic Resonance Imaging (MRI) for two reasons, patient monitoring and MRI sequence synchronization for cardiovascular imaging. The MRI environment severely distorts ECG signals. The Magnetic Field Gradients (MFG) especially induce artifacts, which make ECG analysis during MRI acquisition challenging. Specific signal processing is thus required. An MFG artifact modeling has been proposed for their suppression. However the resulting techniques do not take the ECG signals into account during the model parameter estimation. Recently, ECG denoising based on an artificial ECG model and nonlinear Bayesian filtering has been presented. In this paper, a new MFG artifact suppression method based on nonlinear Bayesian filtering and the unification of the ECG and MFG models is proposed. This new approach enables accurate patient monitoring and outperforms state-of-the-art methods in terms of both QRS detection quality and signal to noise ratio. ©2010 IEEE. Source

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