{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T00:57:35Z","timestamp":1760057855815,"version":"build-2065373602"},"reference-count":22,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2025,2,25]],"date-time":"2025-02-25T00:00:00Z","timestamp":1740441600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Algorithms"],"abstract":"<jats:p>The Coherent Hemodynamic Spectroscopy (CHS) model provides a quantitative framework for modeling cerebral hemodynamics and metabolism, particularly in response to small physiological perturbations. However, in its original approximate formulation it was limited to conditions where parameter changes were constrained to 10\u201320%, making it unsuitable for modeling extreme physiological disruptions such as cardiac arrest. In this study, we present a detailed discussion of the algorithm using the complete CHS model, which extends the original framework by solving partial differential equations without approximations to handle large non-periodic perturbations. This model was applied to data from a previously published cardiac arrest and cardiopulmonary resuscitation (CPR) study in pigs, where cerebral blood flow changed by 100%. While our prior work demonstrated the utility of this approach for analyzing cerebral microvascular and metabolic parameters, it did not include the algorithmic details necessary for reproducibility and broader application. Here, we address this gap by describing the algorithm\u2019s workflow, including the use of non-linear multivariate optimization, and its ability to recover multiple physiological variables, such as the capillary and venule oxygen saturations, and parameters, such as the capillary oxygen diffusion rate, and arterial oxygen saturation. The latter can be valuable when the pulse oximetry measurements are unavailable due to unstable, weak or absent pulse. This study underscores the importance of non-linear modeling in advancing the application of CHS to extreme physiological conditions and highlights its potential for translational research and clinical innovation.<\/jats:p>","DOI":"10.3390\/a18030128","type":"journal-article","created":{"date-parts":[[2025,2,25]],"date-time":"2025-02-25T03:40:12Z","timestamp":1740454812000},"page":"128","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Using Coherent Hemodynamic Spectroscopy Model to Investigate Cardiac Arrest"],"prefix":"10.3390","volume":"18","author":[{"given":"Vladislav","family":"Toronov","sequence":"first","affiliation":[{"name":"Department of Physics, Toronto Metropolitan University, 350 Victoria Street, Toronto, ON M5B 2K3, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nima","family":"Soltani","sequence":"additional","affiliation":[{"name":"Department of Physics, Toronto Metropolitan University, 350 Victoria Street, Toronto, ON M5B 2K3, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Leeanne","family":"Leung","sequence":"additional","affiliation":[{"name":"Department of Physics, Toronto Metropolitan University, 350 Victoria Street, Toronto, ON M5B 2K3, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1596-6778","authenticated-orcid":false,"given":"Rohit","family":"Mohindra","sequence":"additional","affiliation":[{"name":"Schwartz Reisman Emergency Institute, Toronto, ON M5G 1X5, Canada"},{"name":"North York General Hospital, 4001 Leslie St., Toronto, ON M2K 1E1, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Steve","family":"Lin","sequence":"additional","affiliation":[{"name":"Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael\u2019s Hospital, 30 Bond St., Toronto, ON M5B 1W8, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,2,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"202","DOI":"10.1016\/j.neuroimage.2013.03.065","article-title":"Dynamic model for the tissue concentration and oxygen saturation of hemoglobin in relation to blood volume, flow velocity, and oxygen consumption: Implications for functional neuroimaging and co-herent hemodynamics spectroscopy (CHS)","volume":"85","author":"Fantini","year":"2014","journal-title":"Neuroimage"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"132","DOI":"10.1016\/j.jtbi.2015.11.001","article-title":"Nonlinear extension of a hemodynamic linear model for coherent hemodynamics spectroscopy","volume":"389","author":"Sassaroli","year":"2016","journal-title":"J. Theor. Biol."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Khalifehsoltani, N., Rennie, O., Mohindra, R., Lin, S., and Toronov, V. (2023). Tracking Cerebral Microvascular and Metabolic Parameters during Cardiac Arrest and Cardiopulmonary Resuscitation. Appl. Sci., 13.","DOI":"10.3390\/app132212303"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Soltani, N., Mohindra, R., Lin, S., and Toronov, V. (2025). Assessing the Relationship Between Cerebral Metabolic Rate of Oxygen and Redox Cytochrome C Oxidase During Cardiac Arrest and Cardiopulmonary Resuscitation. Appl. Sci., 15.","DOI":"10.20944\/preprints202501.0388.v1"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Erdener, \u015e.E., and Dalkara, T. (2019). Small vessels are a big problem in neurodegeneration and neuroprotection. Front. 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Anesth."}],"container-title":["Algorithms"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1999-4893\/18\/3\/128\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T16:41:52Z","timestamp":1760028112000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1999-4893\/18\/3\/128"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,2,25]]},"references-count":22,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2025,3]]}},"alternative-id":["a18030128"],"URL":"https:\/\/doi.org\/10.3390\/a18030128","relation":{},"ISSN":["1999-4893"],"issn-type":[{"type":"electronic","value":"1999-4893"}],"subject":[],"published":{"date-parts":[[2025,2,25]]}}}