{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,19]],"date-time":"2026-09-19T20:08:52Z","timestamp":1789848532547,"version":"4.0.1"},"reference-count":42,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2026,2,11]],"date-time":"2026-02-11T00:00:00Z","timestamp":1770768000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,2,11]],"date-time":"2026-02-11T00:00:00Z","timestamp":1770768000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/100009153","name":"University of Portsmouth","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100009153","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012317","name":"UCLH Biomedical Research Centre","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100012317","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["physoc.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Experimental Physiology"],"published-print":{"date-parts":[[2026,4]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    Peripheral oxygen saturation () exhibits a complex pattern of fluctuations during hypoxia, which can be quantified using entropy measures.  entropy analysis provides insights into dynamic physiological regulation by non\u2010invasively reflecting the body's capacity to adapt to internal or external physiological challenges. However, the interpretation of  entropy alone is limited without contextualisation and the degree of physiological challenge encountered (e.g. the severity of hypoxia). This proof\u2010of\u2010concept retrospective study analysed continuous 1\u00a0Hz  recordings extracted from MIMIC\u2010III dataset's Intensive Care Unit ICU patients with sepsis (\n                    <jats:italic>n<\/jats:italic>\n                    \u00a0=\u00a0164), chronic obstructive pulmonary disease (COPD) (\n                    <jats:italic>n<\/jats:italic>\n                    \u00a0=\u00a058), acute liver failure (ALF) (\n                    <jats:italic>n<\/jats:italic>\n                    \u00a0=\u00a059), or cirrhosis (\n                    <jats:italic>n<\/jats:italic>\n                    \u00a0=\u00a0169). Sample entropy was computed directly from raw 20\u2010min  signals and normalised to mean  using directional parenclitic deviation (\u03b4), derived from a healthy hypoxia\u2010exposure reference dataset. Cox\u2010regression models assessed 30\u2010day ICU mortality. In sepsis, \u03b4 was significantly higher in non\u2010survivors (hazard ratio (HR)\u00a0=\u00a02.20,\n                    <jats:italic>P\u00a0<\/jats:italic>\n                    &lt;\u00a00.0001) and independently predicted 30\u2010day mortality (HR\u00a0=\u00a01.79,\n                    <jats:italic>P\u00a0<\/jats:italic>\n                    &lt;\u00a00.0001). \u03b4 was not predictive in the COPD, ALF and cirrhosis cohorts. Unlike other patient groups, the cirrhosis group demonstrated unexpected mean negative \u03b4 values, suggesting aberrant regulatory engagement, potentially related to the pathophysiology of hepatopulmonary syndrome. These findings demonstrate that \u03b4 provides physiological contexts to entropy\u2010based  analysis. By linking variability to the severity of hypoxia, this framework enables a more interpretable and a potentially clinically applicable biomarker of systemic regulation in critical illnesses. Future validation across diverse cohorts could support its potential to aid in personalised care within intensive care settings.\n                  <\/jats:p>","DOI":"10.1113\/ep093235","type":"journal-article","created":{"date-parts":[[2026,2,12]],"date-time":"2026-02-12T07:00:21Z","timestamp":1770879621000},"page":"2334-2347","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Interpreting peripheral oxygen saturation variability in critical illness: A directional framework adjusted for hypoxia severity"],"prefix":"10.1113","volume":"111","author":[{"given":"Shuyang Iris","family":"Feng","sequence":"first","affiliation":[{"name":"Network Physiology Lab, UCL Division of Medicine University College London  London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tope","family":"Oyelade","sequence":"additional","affiliation":[{"name":"Network Physiology Lab, UCL Division of Medicine University College London  London UK"},{"name":"School of Medicine Keele University  Staffordshire UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mudra","family":"Ko","sequence":"additional","affiliation":[{"name":"Network Physiology Lab, UCL Division of Medicine University College London  London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yunkai","family":"Zhang","sequence":"additional","affiliation":[{"name":"Network Physiology Lab, UCL Division of Medicine University College London  London UK"},{"name":"School of Medicine and Dentistry University of Central Lancashire  Preston UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Watjana","family":"Lilaonitkul","sequence":"additional","affiliation":[{"name":"Global Business School for Health University College London  London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3506-3111","authenticated-orcid":false,"given":"Thomas B.","family":"Williams","sequence":"additional","affiliation":[{"name":"Extreme Environments Laboratory, School of Psychology, Sport and Health Sciences University of Portsmouth  Portsmouth UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9510-7932","authenticated-orcid":false,"given":"Joseph T.","family":"Costello","sequence":"additional","affiliation":[{"name":"Extreme Environments Laboratory, School of Psychology, Sport and Health Sciences University of Portsmouth  Portsmouth UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0830-2022","authenticated-orcid":false,"given":"Ali R.","family":"Mani","sequence":"additional","affiliation":[{"name":"Network Physiology Lab, UCL Division of Medicine University College London  London UK"},{"name":"Institute for Liver and Digestive Health, UCL Division of Medicine University College London  London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,2,11]]},"reference":[{"key":"e_1_2_9_2_1","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.00003.2023"},{"key":"e_1_2_9_3_1","doi-asserted-by":"publisher","DOI":"10.1183\/09031936.00128008"},{"key":"e_1_2_9_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.dld.2018.09.011"},{"key":"e_1_2_9_5_1","doi-asserted-by":"publisher","DOI":"10.3389\/fphys.2017.00555"},{"key":"e_1_2_9_6_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-022-06301-9"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jointm.2023.03.002"},{"key":"e_1_2_9_8_1","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevLett.89.068102"},{"key":"e_1_2_9_9_1","doi-asserted-by":"publisher","DOI":"10.1089\/ham.2019.0092"},{"key":"e_1_2_9_10_1","doi-asserted-by":"publisher","DOI":"10.3390\/jcm11113180"},{"key":"e_1_2_9_11_1","doi-asserted-by":"publisher","DOI":"10.1097\/SHK.0000000000001453"},{"key":"e_1_2_9_12_1","doi-asserted-by":"publisher","DOI":"10.61186\/phypha.29.1.96"},{"key":"e_1_2_9_13_1","doi-asserted-by":"publisher","DOI":"10.1002\/hep.30139"},{"key":"e_1_2_9_14_1","doi-asserted-by":"publisher","DOI":"10.1186\/s13089-015-0020-x"},{"key":"e_1_2_9_15_1","doi-asserted-by":"publisher","DOI":"10.14814\/phy2.15546"},{"key":"e_1_2_9_16_1","doi-asserted-by":"publisher","DOI":"10.1097\/SHK.0b013e318240b4be"},{"key":"e_1_2_9_17_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0168-8278(12)60003-8"},{"key":"e_1_2_9_18_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(96)90948-4"},{"key":"e_1_2_9_19_1","doi-asserted-by":"publisher","DOI":"10.3748\/wjg.v22.i25.5728"},{"key":"e_1_2_9_20_1","doi-asserted-by":"publisher","DOI":"10.1002\/hep4.1612"},{"key":"e_1_2_9_21_1","doi-asserted-by":"publisher","DOI":"10.1097\/SHK.0000000000000473"},{"key":"e_1_2_9_22_1","doi-asserted-by":"publisher","DOI":"10.14814\/phy2.70407"},{"key":"e_1_2_9_23_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.resp.2013.07.010"},{"key":"e_1_2_9_24_1","doi-asserted-by":"publisher","DOI":"10.3389\/fmed.2023.1060073"},{"key":"e_1_2_9_25_1","doi-asserted-by":"publisher","DOI":"10.1113\/EP088755"},{"key":"e_1_2_9_26_1","doi-asserted-by":"publisher","DOI":"10.1038\/sdata.2016.35"},{"key":"e_1_2_9_27_1","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.332.7551.1202"},{"key":"e_1_2_9_28_1","doi-asserted-by":"publisher","DOI":"10.15326\/jcopdf.7.4.2020.0176"},{"key":"e_1_2_9_29_1","doi-asserted-by":"publisher","DOI":"10.1177\/14799731221119810"},{"key":"e_1_2_9_30_1","doi-asserted-by":"publisher","DOI":"10.1007\/s10620-015-3752-3"},{"key":"e_1_2_9_31_1","doi-asserted-by":"publisher","DOI":"10.1161\/HYPERTENSIONAHA.114.03782"},{"key":"e_1_2_9_32_1","doi-asserted-by":"crossref","unstructured":"Morandotti 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