{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,5,14]],"date-time":"2025-05-14T04:17:08Z","timestamp":1747196228447,"version":"3.40.5"},"reference-count":10,"publisher":"Public Library of Science (PLoS)","issue":"8","license":[{"start":{"date-parts":[[2022,8,30]],"date-time":"2022-08-30T00:00:00Z","timestamp":1661817600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"The National Institute for Health Research (NIHR) Oxford Biomedical Research Centre"},{"name":"The National Institute for Health Research (NIHR) Oxford Biomedical Research Centre"},{"name":"CAMS-Oxford Institute"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:p>Busana <jats:italic>et al<\/jats:italic>. (<jats:ext-link xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" ext-link-type=\"uri\" xlink:href=\"https:\/\/doi.org\/10.1152\/japplphysiol.00871.2020\" xlink:type=\"simple\">doi.org\/10.1152\/japplphysiol.00871.2020<\/jats:ext-link>) published 5 patients with COVID-19 in whom the fraction of non-aerated lung tissue had been quantified by computed tomography. They assumed that shunt flow fraction was proportional to the non-aerated lung fraction, and, by randomly generating 10<jats:sup>6<\/jats:sup> different bimodal distributions for the ventilation-perfusion (<jats:inline-formula id=\"pone.0273214.e001\"><jats:alternatives><jats:graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" id=\"pone.0273214.e001g\" mimetype=\"image\" position=\"anchor\" xlink:href=\"info:doi\/10.1371\/journal.pone.0273214.e001\" xlink:type=\"simple\"\/><mml:math xmlns:mml=\"http:\/\/www.w3.org\/1998\/Math\/MathML\" display=\"inline\" id=\"M1\"><mml:mrow><mml:mover accent=\"true\"><mml:mi mathvariant=\"normal\">V<\/mml:mi><mml:mo>\u02d9<\/mml:mo><\/mml:mover><mml:mo>\/<\/mml:mo><mml:mover accent=\"true\"><mml:mi mathvariant=\"normal\">Q<\/mml:mi><mml:mo>\u02d9<\/mml:mo><\/mml:mover><\/mml:mrow><\/mml:math><\/jats:alternatives><\/jats:inline-formula>) ratios in the lung, specified as sets of paired values {<jats:inline-formula id=\"pone.0273214.e002\"><jats:alternatives><jats:graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" id=\"pone.0273214.e002g\" mimetype=\"image\" position=\"anchor\" xlink:href=\"info:doi\/10.1371\/journal.pone.0273214.e002\" xlink:type=\"simple\"\/><mml:math xmlns:mml=\"http:\/\/www.w3.org\/1998\/Math\/MathML\" display=\"inline\" id=\"M2\"><mml:mrow><mml:mover accent=\"true\"><mml:mi mathvariant=\"normal\">V<\/mml:mi><mml:mo>\u02d9<\/mml:mo><\/mml:mover><mml:mi mathvariant=\"normal\">i<\/mml:mi><mml:mo>,<\/mml:mo><mml:mspace width=\"0.25em\"\/><mml:mover accent=\"true\"><mml:mi mathvariant=\"normal\">Q<\/mml:mi><mml:mo>\u02d9<\/mml:mo><\/mml:mover><mml:mi mathvariant=\"normal\">i<\/mml:mi><\/mml:mrow><\/mml:math><\/jats:alternatives><\/jats:inline-formula>}, sought to identify as solutions those that generated the observed arterial partial pressures of CO<jats:sub>2<\/jats:sub> and O<jats:sub>2<\/jats:sub> (Pa<jats:sub>CO2<\/jats:sub> and Pa<jats:sub>O2<\/jats:sub>). Our study sought to develop a direct method of calculation to replace the approach of randomly generating different distributions, and so provide more accurate solutions that were within the measurement error of the blood-gas data. For the one patient in whom Busana <jats:italic>et al<\/jats:italic>. did not find solutions, we demonstrated that the assumed shunt flow fraction led to a non-shunt blood flow that was too low to support the required gas exchange. For the other four patients, we found precise solutions (prediction error &lt; 1x10<jats:sup>-3<\/jats:sup> mmHg for both Pa<jats:sub>CO2<\/jats:sub> and Pa<jats:sub>O2<\/jats:sub>), with distributions qualitatively similar to those of Busana <jats:italic>et al<\/jats:italic>. These distributions were extremely wide and unlikely to be physically realisable, because they predict the maintenance of very large concentration gradients in regions of the lung where convection is slow. We consider that these wide distributions arise because the assumed value for shunt flow is too low in these patients, and we discuss possible reasons why the assumption relating to shunt flow fraction may break down in COVID-19 pneumonia.<\/jats:p>","DOI":"10.1371\/journal.pone.0273214","type":"journal-article","created":{"date-parts":[[2022,8,30]],"date-time":"2022-08-30T18:31:44Z","timestamp":1661884304000},"page":"e0273214","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["Identifying putative ventilation-perfusion distributions in COVID-19 pneumonia"],"prefix":"10.1371","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0245-0844","authenticated-orcid":true,"given":"Haopeng","family":"Xu","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nayia","family":"Petousi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Peter A.","family":"Robbins","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"340","published-online":{"date-parts":[[2022,8,30]]},"reference":[{"issue":"10","key":"pone.0273214.ref001","doi-asserted-by":"crossref","first-page":"1299","DOI":"10.1164\/rccm.202003-0817LE","article-title":"COVID-19 Does Not Lead to a \"Typical\" Acute Respiratory Distress Syndrome","volume":"201","author":"L Gattinoni","year":"2020","journal-title":"Am J Respir Crit Care Med"},{"issue":"3","key":"pone.0273214.ref002","first-page":"865","article-title":"The","volume":"130","author":"M Busana","year":"2021","journal-title":"impact of ventilation-perfusion inequality in COVID-19: a computational model. 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