{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,10]],"date-time":"2026-04-10T10:08:04Z","timestamp":1775815684565,"version":"3.50.1"},"reference-count":67,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2023,11,24]],"date-time":"2023-11-24T00:00:00Z","timestamp":1700784000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Key R&amp;D Program of China","award":["2021YFC2501500"],"award-info":[{"award-number":["2021YFC2501500"]}]},{"name":"National Key R&amp;D Program of China","award":["62001470"],"award-info":[{"award-number":["62001470"]}]},{"name":"National Key R&amp;D Program of China","award":["ZR2020QF021"],"award-info":[{"award-number":["ZR2020QF021"]}]},{"name":"National Natural Science Foundation of China","award":["2021YFC2501500"],"award-info":[{"award-number":["2021YFC2501500"]}]},{"name":"National Natural Science Foundation of China","award":["62001470"],"award-info":[{"award-number":["62001470"]}]},{"name":"National Natural Science Foundation of China","award":["ZR2020QF021"],"award-info":[{"award-number":["ZR2020QF021"]}]},{"name":"Natural Science Foundation of Shandong Province, China","award":["2021YFC2501500"],"award-info":[{"award-number":["2021YFC2501500"]}]},{"name":"Natural Science Foundation of Shandong Province, China","award":["62001470"],"award-info":[{"award-number":["62001470"]}]},{"name":"Natural Science Foundation of Shandong Province, China","award":["ZR2020QF021"],"award-info":[{"award-number":["ZR2020QF021"]}]},{"name":"Youth Innovation Promotion Association CAS","award":["2021YFC2501500"],"award-info":[{"award-number":["2021YFC2501500"]}]},{"name":"Youth Innovation Promotion Association CAS","award":["62001470"],"award-info":[{"award-number":["62001470"]}]},{"name":"Youth Innovation Promotion Association CAS","award":["ZR2020QF021"],"award-info":[{"award-number":["ZR2020QF021"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>Wearable technologies face challenges due to signal instability, hindering their usage. Thus, it is crucial to comprehend the connection between dynamic patterns in photoplethysmography (PPG) signals and cardiovascular health. In our study, we collected 401 multimodal recordings from two public databases, evaluating hemodynamic conditions like blood pressure (BP), cardiac output (CO), vascular compliance (C), and peripheral resistance (R). Using irregular-resampling auto-spectral analysis (IRASA), we quantified chaotic components in PPG signals and employed different methods to measure the fractal dimension (FD) and entropy. Our findings revealed that in surgery patients, the power of chaotic components increased with vascular stiffness. As the intensity of CO fluctuations increased, there was a notable strengthening in the correlation between most complexity measures of PPG and these parameters. Interestingly, some conventional morphological features displayed a significant decrease in correlation, indicating a shift from a static to dynamic scenario. Healthy subjects exhibited a higher percentage of chaotic components, and the correlation between complexity measures and hemodynamics in this group tended to be more pronounced. Causal analysis showed that hemodynamic fluctuations are main influencers for FD changes, with observed feedback in most cases. In conclusion, understanding chaotic patterns in PPG signals is vital for assessing cardiovascular health, especially in individuals with unstable hemodynamics or during ambulatory testing. These insights can help overcome the challenges faced by wearable technologies and enhance their usage in real-world scenarios.<\/jats:p>","DOI":"10.3390\/e25121582","type":"journal-article","created":{"date-parts":[[2023,11,24]],"date-time":"2023-11-24T11:19:46Z","timestamp":1700824786000},"page":"1582","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Analysis of the Chaotic Component of Photoplethysmography and Its Association with Hemodynamic Parameters"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6242-8868","authenticated-orcid":false,"given":"Xiaoman","family":"Xing","sequence":"first","affiliation":[{"name":"School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Sciences and Technology of China, Suzhou 215163, China"},{"name":"Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5848-7147","authenticated-orcid":false,"given":"Wen-Fei","family":"Dong","sequence":"additional","affiliation":[{"name":"Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Renjie","family":"Xiao","sequence":"additional","affiliation":[{"name":"Medical Health Information Center, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mingxuan","family":"Song","sequence":"additional","affiliation":[{"name":"Suzhou GK Medtech Science and Technology Development (Group) Co., Ltd., Suzhou 215163, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chenyu","family":"Jiang","sequence":"additional","affiliation":[{"name":"Jinan Guoke Medical Technology Development Co., Ltd., Jinan 250100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,11,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1038\/s41746-019-0136-7","article-title":"The use of photoplethysmography for assessing hypertension","volume":"2","author":"Elgendi","year":"2019","journal-title":"npj Digit. 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