Master thesis

Abstract

The aim of this study was to compare an medical-grade electrocardiography (ECG) system with an ECG sensor of an DiY (Do-it-Yourself) hardware toolkit BITalino. Twenty-three participants underwent simultaneous ECG recordings with the two instruments while watching pleasant and unpleasant pictures of the “International Affective Picture System” (IAPS). Both picture conditions (pleasant and unpleasant) were presented 2 times each, resulting in four blocks. Each of them contained 60 pictures, each presented for 4 seconds and separated from each other with a fixation cross showed for one second, resulting in an duration of 5 minutes for each IAPS picture block. Before and after two blocks of different conditions, a baseline block, consisting of a picture with a gray fixation cross on a black background, was added with a duration of 5 minutes. Therefore participants had to sit still for 35 minutes (7 blocks each 5 minutes) in total. For each subject, common ECG parameters (heart rate (HR), root mean square of successive differences (RMSSD), low frequency component of the heart rate variability (LF), high frequency component of the heart rate variability (HF), ratio between low and high frequency component of the heart rate variability (LF/HF)) were extracted from seven 5 minutes blocks of the ECG data from each ECG system. The analysis of variance (ANOVA), the Intraclass correlation coefficients (ICC) and the Bland-Altman Limits of Agreement (LoA) method served as criteria for measurement agreement. None of the parameters showed differences between the recording devices in the results of the ANOVA. In addition, only the HR paramter showed differences between the three conditions (pleasant IAPS, unpleasant IAPS, baseline (fixation cross)). All parameters except the LF/HF ratio, showed an excellent agreement (> 80%) between both devices in ICC analysis for all blocks. No criteria for Bland Altman’s LoA and bias were found in the literature regarding ECG parameters. Comparing the results of the current study with results in the researched papers showed excellent agreement for all parameters, except for the LF/HF ratio. Due to the results of ICC and Bland-Altman method, BITalino can be considered as an equivalent recording device for stationary ECG recordings in psychophysiological experiments.