Použití textilních elektrod pro odhad dechové aktivity z EKG signálu

Abstract

Estimating respiratory activity from a recording of cardiac activity using electrocardiography (ECG) offers the possibility of expanding the informational value of a commonly recorded biosignal without the need for a separate respiratory sensor. In light of the development of wearable systems and long-term monitoring, it is also important to verify whether textile electrodes can be used for this purpose. The aim of this thesis was to verify the possibility of estimating respiratory activity from the ECG signal with a focus on the use of textile electrodes and to compare their usability with reference Ag/AgCl gel electrodes. The thesis also included the development of a software application for processing, analyzing, and comparing the measured signals. As part of the experiment, a proprietary dataset was collected from 20 healthy subjects aged 18 to 32. The ECG was recorded in Einthoven’s II lead using reference Ag/AgCl gel electrodes and two types of textile electrodes. Reference respiration was measured using a chest sensor. To estimate the respiratory curve from the ECG, nine methods were implemented and evaluated, based on amplitude modulation, empirical modal decomposition, changes in the area of the QRS complex, respiratory sinus arrhythmia, and curve slope analysis. The evaluation was performed using cross-correlation, mean absolute error of respiratory rate and apnea duration, and percentage error of the number of inhalations and exhalations. The best results were achieved primarily by the method based on amplitude modulation of the R and S waves and the method based on the maximum downward slope in the vicinity of the R wave. The SM-RS method showed the highest average correlation for all three types of electrodes, specifically 0.8872 for Ag/AgCl, 0.8566 for Tex-1, and 0.8821 for Tex-2. The lowest mean absolute error in respiratory rate was recorded for the SM-RS method with the Tex-2 electrode, where it was 0.2132 breaths/min. The results of this study show that textile electrodes can be used to estimate respiratory activity from the ECG signal and that, with a suitably chosen processing method, they can provide results comparable to those of reference Ag/AgCl gel electrodes.