The availability of an automatic pulse detection during out-of-hospital cardiac arrest (OHCA) would allow the rapid identi cation of cardiac arrest and the prompt detection of return of spontaneous circulation. The aim of this study was to develop a reliable pulse detection algorithm using the electrocardiogram (ECG) and thoracic impedance (TI), the signals available in most de brilators. The dataset used in the study consisted of 1140 ECG and TI segments from 187 OHCA patients, whereof 792 were labelled as pulse-generating rhythm (PR) and 348 as pulseless electrical activity (PEA) by a pool of experts in OHCA. First, an adaptive ltering scheme was used to extract the impedance circulation component and its rst derivative from the TI. Then, the wavelet decomposition of the ECG was carried out to obtain the different subband components and the denoised ECG. Pulse/no-pulse (PR/PEA) discrimination features were extracted from those signals and fed into a support vector machine (SVM) classi er that made the pulse/nopulse decision. A quasi-strati ed and patient wise nested cross validation procedure was used to select the best feature subset and to tune the SVM hyperparameters. This procedure was repeated 50 times to estimate the statistical distributions of the performance metrics of the method. The optimal solution consisted in a ve feature classi er that yielded a mean (standard deviation) sensitivity, speci city, balanced accuracy and total accuracy of 92.4% (0.7), 93.0% (0.8), 92.7% (0.5) and 92.6%(0.5), respectively. When compared to available methods, our solution presented an improvement in balanced accuracy of at least 2.5 points. A reliable pulse detection algorithm for OHCA using the signals available in de brillators was acomplished.

This work was supported in part by the Spanish Ministry of Science, Innovation and Universities, jointly with the Fondo Europeo de Desarrollo Regional (FEDER), under Grant RTI2018-101475-Bl00, and in part by the Basque Government under Grant IT-1229-19.