Nonlinear analysis of electrodermal activity signals for healthy subjects and patients with chronic obstructive pulmonary disease
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It is known that signals recorded from physiological systems represent nonlinear features. Several recent studies report that quantitative information about signal complexity is obtained by using nonlinear analysis algorithms. Chronic obstructive pulmonary disease (COPD) is one of the causes of mortality worldwide with an increasing prevalence. This study aims to investigate nonlinear parameters such as largest Lyapunov exponent (LLE) and correlation dimension of electrodermal activity signals recorded from healthy subjects and patients with COPD. Electrodermal activity signals recorded from 14 healthy subjects and 24 patients with COPD were analysed. Auditory and tactile stimuli were applied at different time intervals during the recording process. Signals were reconstructed in the phase space compatible with theory and LLE and correlation dimension values were calculated. Statistical analysis was performed by using Shapiro–Wilk normality test, one-way analysis of variance (ANOVA) with Bonferroni post-test and Kruskal–Wallis non-parametric test. It was determined that the chaoticity and the complexity of the system increased in the presence of COPD. The systematic auditory stimuli increases chaoticity more than random auditory stimuli. Furthermore it was observed that participants develop habituation to the same auditory stimuli in time. There is no significant difference between COPD groups. Different results were found for the tactile stimuli applied to right or left ear. The results revealed that the nonlinear analysis of physiological data can be used for the development of new strategies for the diagnosis of chronic diseases.
KeywordsChronic obstructive pulmonary disease Electrodermal activity Nonlinear analysis Phase space reconstruction
Authors gratefully acknowledge assistance provided by Adnan Menderes University, Aydın / Turkey (grant number: TPF-15069). We also thank Associate Prof. İmran Kurt Ömürlü and Research Assistant Fulden Cantaş for their valuable contributions to this paper.
Compliance with ethical standards
Conflict of interest
The authors declare that there are no conflicts of interest.
Research involving human participants and/or animals
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors.
Informed consent was obtained from all individual participants included in the study.
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