Porcine model for CPR artifact generation in ECG signals

Abstract

Interruption of cardiopulmonary resuscitation (CPR) worsens the chance for a successful defibrillation with stable return of spontaneous circulation. Therefore “no flow times” (NFT) have to be minimized. However, analysis of the electrocardiogram (ECG) for fibrillation detection requires interruption of CPR with the ECG-analysis algorithms currently implemented in (automatic external) defibrillators. In contrast, ECG-analysis during ongoing cardiac massage could considerably reduce NFT. New analyzing algorithms should be optimized for removal of CPR-artifacts from the ECG. In order to test these algorithms “corrupted” ECGs are needed.We have designed a pig experimental model for generating CPR artifacts in the ECG. Either the pig’s sinus rhythm ECG or the pig’s ventricular fibrillation ECG (or any ECG previously recorded in human victims) is fed in into the pigs thorax, by this the (dead) animal representing an “ECG generator” which allows to record the electrical potential changes in the defibrillator pad electrodes as induced during CPR. Performing CPR at the same time, we were able to generate ECGs with true CPR artifacts. The corrupted ECG signal as well as the corresponding reference signal (pressure or force or equivalent) can be recorded simultaneouslyThe electrical signals recorded via defibrillator pads were nearly identical with the pigs live ECG. Using a black box modeling approach (MATLAB) we were able to define an appropriate transfer function. When analyzing the transfer function, the pig was identified to act as a high pass filter considerably attenuating frequencies below 1–2 Hz. Using inverse transformation we could reconstitute the “true” corrupted ECG signal.Our experimental approach provides a sound basis to provide the data needed for extensive testing of artifact removal algorithms. We are able to generate ECG artifacts even resembling situations when lay people or unprofessional rescuers perform CPR.KeywordsCPRartifact reductionECG analysispig modeltransfer function