{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T13:00:41Z","timestamp":1791378041644,"version":"4.3.2"},"reference-count":29,"publisher":"American Physiological Society","issue":"6","funder":[{"DOI":"10.13039\/501100000925","name":"Department of Health, Australian Government | National Health and Medical Research Council","doi-asserted-by":"publisher","award":["1188514"],"award-info":[{"award-number":["1188514"]}],"id":[{"id":"10.13039\/501100000925","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001030","name":"National Heart Foundation of Australia","doi-asserted-by":"publisher","award":["101853"],"award-info":[{"award-number":["101853"]}],"id":[{"id":"10.13039\/501100001030","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["journals.physiology.org"],"crossmark-restriction":true},"short-container-title":["American Journal of Physiology-Regulatory, Integrative and Comparative Physiology"],"published-print":{"date-parts":[[2021,12,1]]},"abstract":"<jats:p> The changes in brain perfusion and oxygenation in critical illness, which are thought to contribute to brain dysfunction, are unclear due to the lack of methods to measure these variables. We have developed a technique to chronically measure cerebral tissue perfusion and oxygen tension in unanesthetized sheep. Using this technique, we have determined the changes in cerebral perfusion and Po<jats:sub>2<\/jats:sub> during the development of ovine sepsis. In adult Merino ewes, fiber-optic probes were implanted in the brain, renal cortex, and renal medulla to measure tissue perfusion, oxygen tension (Po<jats:sub>2<\/jats:sub>), and temperature, and flow probes were implanted on the pulmonary and renal arteries. Conscious sheep were infused with live Escherichia coli for 24 h, which induced hyperdynamic sepsis; mean arterial pressure decreased (from 85.2\u2009\u00b1\u20095.6 to 71.5\u2009\u00b1\u20098.7 mmHg), while cardiac output (from 4.12\u2009\u00b1\u20090.70 to 6.15\u2009\u00b1\u20091.26 L\/min) and total peripheral conductance (from 48.9\u2009\u00b1\u20098.5 to 86.8\u2009\u00b1\u200911.5 mL\/min\/mmHg) increased ( n = 8, all P &lt; 0.001) and arterial Po<jats:sub>2<\/jats:sub> decreased (from 104\u2009\u00b1\u20098 to 83\u2009\u00b1\u200910 mmHg; P &lt; 0.01). Cerebral perfusion tended to decrease acutely, although this did not reach significance, but there was a significant and sustained decrease in cerebral tissue Po<jats:sub>2<\/jats:sub> (from 32.2\u2009\u00b1\u200910.1 to 18.8\u2009\u00b1\u200911.7 mmHg) after 3 h and to 22.8\u2009\u00b1\u20095.2 mmHg after 24 h of sepsis ( P &lt; 0.02). Sepsis induced large reductions in both renal medullary perfusion and Po<jats:sub>2<\/jats:sub> but had no effect in the renal cortex. In ovine sepsis, there is an early decrease in cerebral Po<jats:sub>2<\/jats:sub> that is maintained for 24 h despite minimal changes in cerebral perfusion. Cerebral hypoxia may be one of the factors causing sepsis-induced malaise and lethargy. <\/jats:p>","DOI":"10.1152\/ajpregu.00184.2021","type":"journal-article","created":{"date-parts":[[2021,11,17]],"date-time":"2021-11-17T13:02:09Z","timestamp":1637154129000},"page":"R990-R996","update-policy":"https:\/\/doi.org\/10.1152\/aps-crossmark-policy","source":"Crossref","is-referenced-by-count":12,"title":["Rapid and persistent decrease in brain tissue oxygenation in ovine gram-negative sepsis"],"prefix":"10.1152","volume":"321","author":[{"given":"Nobuki","family":"Okazaki","sequence":"first","affiliation":[{"name":"Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia"},{"name":"Department of Anesthesiology and Resuscitology, Okayama University, Okayama, 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