{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T07:22:09Z","timestamp":1787728929213,"version":"build-2784847793"},"reference-count":29,"publisher":"IOP Publishing","issue":"8","license":[{"start":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T00:00:00Z","timestamp":1787702400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/publishingsupport.iopscience.iop.org\/iop-standard\/v1"},{"start":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T00:00:00Z","timestamp":1787702400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/iopscience.iop.org\/info\/page\/text-and-data-mining"},{"start":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T00:00:00Z","timestamp":1787702400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/publishingsupport.iopscience.iop.org\/questions\/alternative-author-rights-policies\/"},{"start":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T00:00:00Z","timestamp":1787702400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/publishingsupport.iopscience.iop.org\/questions\/alternative-author-rights-policies\/"}],"content-domain":{"domain":["iopscience.iop.org"],"crossmark-restriction":false},"short-container-title":["Physiol. Meas."],"published-print":{"date-parts":[[2026,8,31]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    <jats:italic>Objective.<\/jats:italic>\n                    The composition of alveolar gases is based on theoretical assumptions. The role of expired samples at the airway opening in representing the true value of mean alveolar gas remains a subject of debate. We hypothesized that phase III of oxygrams and capnograms obtained at the airway opening must be qualitative similar to the one found at the lung acini. The aim of this study is to test this hypothesis, analyzing the phase III of breath-by-breath samples of airway and alveolar gases from mechanically ventilated patients.\n                    <jats:italic>Approach.<\/jats:italic>\n                    The study compared expired gases at the airway opening and direct gas samples taken from peripheral lung parenchyma in ventilated patients undergoing thoracic surgery. We used video-assisted lobectomies as a model to get direct alveolar gas samples from the lobe that was removed by surgery.\n                    <jats:italic>Main results.<\/jats:italic>\n                    In ten anesthetized patients before lobectomy, the corresponding lung lobe was punctured by a 20 G angiocath at \u223c5 mm of depth and then connected via a sampling line to sidestream and mainstream capnographs. An oscillating pattern in synchrony with the mechanical breath cycles was observed in the alveolar CO\n                    <jats:sub>2<\/jats:sub>\n                    and O\n                    <jats:sub>2<\/jats:sub>\n                    samples. The alveolar capnograms and oxygrams revealed an absence of phase I, very short phase II, and a similar phase III. The slope of phase III of the expired curves at the airway opening [median 2.20 (inter-quartile range 1.28) mmHg s\n                    <jats:sup>\u22121<\/jats:sup>\n                    ] were similar to the one of the alveolar mainstream capnograms [median 2.18 (inter-quartile range 1.24) mmHg s\n                    <jats:sup>\u22121<\/jats:sup>\n                    ;\n                    <jats:italic>p<\/jats:italic>\n                    = 0.76].\n                    <jats:italic>Significance.<\/jats:italic>\n                    Our findings suggest that alveolar gas can be reliably sampled at the airway opening. The similarity in the slopes of phase III between airway and alveolar samples highlights the significance of continuous gas diffusion through the alveolar-capillary membrane as well as the presence of convection- and diffusion-dependent inhomogeneities in their origin.\n                  <\/jats:p>","DOI":"10.1088\/1361-6579\/ae9036","type":"journal-article","created":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T22:55:13Z","timestamp":1784933713000},"page":"085028","update-policy":"https:\/\/doi.org\/10.1088\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Direct measurements of alveolar gas in mechanically ventilated humans\n                    <sup>*<\/sup>"],"prefix":"10.1088","volume":"47","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3893-4418","authenticated-orcid":true,"given":"Gerardo","family":"Tusman","sequence":"first","affiliation":[{"name":"Hospital Privado de Comunidad"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mat\u00edas","family":"Nicol\u00e1s","sequence":"additional","affiliation":[{"name":"Hospital Privado de Comunidad"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alejandro","family":"Carmona","sequence":"additional","affiliation":[{"name":"Hospital Privado de Comunidad"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fernando","family":"Suarez Sipmann","sequence":"additional","affiliation":[{"name":"CIBERES"},{"name":"Universidad Autonoma de Madrid"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stephan H","family":"B\u00f6hm","sequence":"additional","affiliation":[{"name":"Rostock University Medical Center"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"266","published-online":{"date-parts":[[2026,8,26]]},"reference":[{"key":"pmeaae9036bib1","doi-asserted-by":"publisher","first-page":"444","DOI":"10.1164\/art.1947.55.5.444","type":"journal-article","article-title":"Simultaneous samples of alveolar air from each lung and parts Thereof, a preliminary report of a method using bronchial catheterization","volume":"5","author":"Birath","year":"1947","journal-title":"Am. Rev. Tuberc."},{"key":"pmeaae9036bib2","doi-asserted-by":"publisher","first-page":"838","DOI":"10.1152\/jappl.1985.59.3.838","type":"journal-article","article-title":"Convection-and diffusion-dependent ventilation maldistribution in normal subjects","volume":"59","author":"Crawford","year":"1985","journal-title":"J. Appl. Physiol."},{"key":"pmeaae9036bib3","doi-asserted-by":"publisher","first-page":"535","DOI":"10.1152\/jappl.1952.4.7.535","type":"journal-article","article-title":"Alveolar CO2 during the respiratory cycle","volume":"4","author":"DuBois","year":"1952","journal-title":"J. Appl. Physiol."},{"key":"pmeaae9036bib4","first-page":"191","type":"journal-article","article-title":"Volumen inefficax Bemerkungen zur Frage des sch\u00e4dlichen Raumes Uppsala L\u00e4kareforen Forhandl","volume":"44","author":"Enghoff","year":"1938"},{"key":"pmeaae9036bib5","doi-asserted-by":"publisher","first-page":"517","DOI":"10.1172\/JCI102922","type":"journal-article","article-title":"Alveolar and arterial oxygen tensions and the significance of the alveolar-arterial oxygen tension difference in normal men","volume":"33","author":"Filley","year":"1954","journal-title":"J. Clin. Invest."},{"key":"pmeaae9036bib6","doi-asserted-by":"publisher","first-page":"245","DOI":"10.1093\/bja\/57.3.245","type":"journal-article","article-title":"Deadspace, invasive and non-invasive","volume":"57","author":"Fletcher","year":"1985","journal-title":"Br. J. Anaesth."},{"key":"pmeaae9036bib7","doi-asserted-by":"publisher","first-page":"405","DOI":"10.1152\/ajplegacy.1948.154.3.405","type":"journal-article","article-title":"Lung function studies II. The respiratory dead space","volume":"154","author":"Fowler","year":"1948","journal-title":"Am. J. Physiol."},{"key":"pmeaae9036bib8","doi-asserted-by":"publisher","first-page":"469","DOI":"10.1159\/000368087","type":"journal-article","article-title":"Functional bronchoscopy: development of a new bronchoscopic method for real-time gas exchange assessment of lobes and lung segments","volume":"88","author":"Freitag","year":"2014","journal-title":"Respiration"},{"key":"pmeaae9036bib9","doi-asserted-by":"publisher","first-page":"401","DOI":"10.1002\/ar.1092200410","type":"journal-article","article-title":"Morphometry of the human pulmonary acinus","volume":"220","author":"Haefeli\u2010bleuer","year":"1988","journal-title":"Anat. Rec."},{"key":"pmeaae9036bib10","doi-asserted-by":"publisher","first-page":"225","DOI":"10.1113\/jphysiol.1905.sp001081","type":"journal-article","article-title":"The regulation of the lung-ventilation","volume":"32","author":"Haldane","year":"1905","journal-title":"J. Physiol."},{"key":"pmeaae9036bib11","doi-asserted-by":"publisher","first-page":"431","DOI":"10.1113\/jphysiol.1914.sp001635","type":"journal-article","article-title":"On the average composition of the alveolar air and its variations during the respiratory cycle","volume":"47","author":"Krogh","year":"1914","journal-title":"J. Physiol."},{"key":"pmeaae9036bib12","doi-asserted-by":"publisher","first-page":"617","DOI":"10.1172\/JCI102772","type":"journal-article","article-title":"Lobar alveolar gas concentrations: effect of body position","volume":"32","author":"Martin","year":"1953","journal-title":"J. Clin. Invest."},{"key":"pmeaae9036bib13","doi-asserted-by":"publisher","first-page":"383","DOI":"10.1152\/jappl.1960.15.3.383","type":"journal-article","article-title":"Respiratory dead space and arterial to end-tidal CO2 difference in anesthetized man","volume":"15","author":"Nunn","year":"1960","journal-title":"J. Appl. Physiol."},{"key":"pmeaae9036bib14","doi-asserted-by":"publisher","first-page":"380","DOI":"10.1378\/chest.50.4.380","type":"journal-article","article-title":"The arterial-alveolar carbon dioxide tension gradient in diagnosis of pulmonary embolus","volume":"50","author":"Nutter","year":"1966","journal-title":"Dis. Chest"},{"key":"pmeaae9036bib15","doi-asserted-by":"publisher","first-page":"89","DOI":"10.1007\/BF01880760","type":"journal-article","article-title":"The assessment of gas exchange by automated analysis of O2 and CO2 alveolar to arterial differences","volume":"3","author":"Paoletti","year":"1986","journal-title":"Int. J. Clin. Monit. Comput."},{"key":"pmeaae9036bib16","doi-asserted-by":"publisher","DOI":"10.1117\/1.3556719","type":"journal-article","article-title":"In situ imaging of lung alveoli with an optical coherence tomography needle probe","volume":"16","author":"Quirk","year":"2011","journal-title":"J. Biomed. Opt."},{"key":"pmeaae9036bib17","doi-asserted-by":"publisher","first-page":"21","DOI":"10.1152\/ajplegacy.1949.158.1.21","type":"journal-article","article-title":"A concept of mean alveolar air and the ventilation-blood flow relationships during pulmonary gas exchange","volume":"158","author":"Rahn","year":"1949","journal-title":"Am. J. Physiol."},{"key":"pmeaae9036bib18","doi-asserted-by":"publisher","first-page":"825","DOI":"10.1152\/jappl.1949.1.12.825","type":"journal-article","article-title":"\u2018Ideal\u2019alveolar air and the analysis of ventilation-perfusion relationships in the lungs","volume":"1","author":"Riley","year":"1949","journal-title":"J. Appl. Physiol."},{"key":"pmeaae9036bib19","doi-asserted-by":"publisher","first-page":"860","DOI":"10.1152\/physrev.1955.35.4.860","type":"journal-article","article-title":"The respiratory dead space","volume":"35","author":"Rossier","year":"1955","journal-title":"Physiol. Rev."},{"key":"pmeaae9036bib20","doi-asserted-by":"publisher","first-page":"2086","DOI":"10.1152\/jappl.1995.79.6.2086","type":"journal-article","article-title":"Estimation of arterial PCO2 in the elderly","volume":"79","author":"St Croix","year":"1995","journal-title":"J. Appl. Physiol."},{"key":"pmeaae9036bib21","doi-asserted-by":"publisher","first-page":"99","DOI":"10.1016\/j.resp.2013.06.020","type":"journal-article","article-title":"Corrections of Enghoff\u2019s dead space formula for shunt effects still overestimate Bohr\u2019s dead space","volume":"189","author":"Suarez-Sipmann","year":"2013","journal-title":"Respir. Physiol. Neurobiol."},{"key":"pmeaae9036bib22","doi-asserted-by":"publisher","DOI":"10.1016\/j.resp.2025.104474","type":"journal-article","article-title":"Determination of PAO2 by the \u201cideal\u201d alveolar gas concept and by MIGET in ventilated animals","volume":"338","author":"Tusman","year":"2025b","journal-title":"Respir. Physiol. Neurobiol."},{"key":"pmeaae9036bib23","doi-asserted-by":"publisher","first-page":"1556","DOI":"10.1089\/respcare.13059","type":"journal-article","article-title":"Feasibility of oxygraphy for the noninvasive measurement of PAO2 in anesthetized patients","volume":"70","author":"Tusman","year":"2025a","journal-title":"Respir. Care"},{"key":"pmeaae9036bib24","doi-asserted-by":"publisher","first-page":"866","DOI":"10.1213\/ANE.0b013e318247f6cc","type":"journal-article","article-title":"Rationale of dead space measurement by volumetric capnography","volume":"114","author":"Tusman","year":"2012a","journal-title":"Anesth. Analg."},{"key":"pmeaae9036bib25","first-page":"870","type":"journal-article","article-title":"Validation of Bohr dead space measured by volumetric capnography","volume":"37","author":"Tusman","year":"2011b"},{"key":"pmeaae9036bib26","doi-asserted-by":"publisher","first-page":"2269","DOI":"10.1152\/jappl.1990.69.6.2269","type":"journal-article","article-title":"Model simulations of gas mixing and ventilation distribution in the human lung","volume":"69","author":"Verbanck","year":"1990","journal-title":"J. Appl. Physiol."},{"key":"pmeaae9036bib27","doi-asserted-by":"publisher","first-page":"5","DOI":"10.1016\/j.resp.2018.09.010","type":"journal-article","article-title":"A simulation study of diffusion-convection interaction and its effect on multiple breaths washout indices","volume":"258","author":"Verbanck","year":"2018","journal-title":"Respir. Physiol. Neurobiol."},{"key":"pmeaae9036bib28","doi-asserted-by":"publisher","first-page":"588","DOI":"10.1152\/jappl.1974.36.5.588","type":"journal-article","article-title":"Measurement of continuous distributions of ventilation\u2013perfusion ratios: theory","volume":"36","author":"Wagner","year":"1974","journal-title":"J. Appl. Physiol."},{"key":"pmeaae9036bib29","doi-asserted-by":"publisher","first-page":"405","DOI":"10.1152\/jappl.1960.15.3.405","type":"journal-article","article-title":"Distribution of blood flow and ventilation-perfusion ratio in the lung, measured with radioactive CO2","volume":"15","author":"West","year":"1960","journal-title":"J. Appl. Physiol."}],"container-title":["Physiological Measurement"],"original-title":[],"link":[{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6579\/ae9036","content-type":"text\/html","content-version":"am","intended-application":"text-mining"},{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6579\/ae9036\/pdf","content-type":"application\/pdf","content-version":"am","intended-application":"text-mining"},{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6579\/ae9036","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6579\/ae9036\/pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6579\/ae9036\/pdf","content-type":"application\/pdf","content-version":"am","intended-application":"syndication"},{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6579\/ae9036\/pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6579\/ae9036\/pdf","content-type":"application\/pdf","content-version":"am","intended-application":"similarity-checking"},{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6579\/ae9036\/pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T06:35:22Z","timestamp":1787726122000},"score":1,"resource":{"primary":{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6579\/ae9036"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,26]]},"references-count":29,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2026,8,26]]},"published-print":{"date-parts":[[2026,8,31]]}},"URL":"https:\/\/doi.org\/10.1088\/1361-6579\/ae9036","relation":{},"ISSN":["0967-3334","1361-6579"],"issn-type":[{"value":"0967-3334","type":"print"},{"value":"1361-6579","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,26]]},"assertion":[{"value":"Direct measurements of alveolar gas in mechanically ventilated humans\n                      *","name":"article_title","label":"Article Title"},{"value":"Physiological Measurement","name":"journal_title","label":"Journal Title"},{"value":"paper","name":"article_type","label":"Article Type"},{"value":"\u00a9 2026 Institute of Physics and Engineering in Medicine. All rights, including for text and data mining, AI training, and similar technologies, are reserved.","name":"copyright_information","label":"Copyright Information"},{"value":"2026-03-14","name":"date_received","label":"Date Received","group":{"name":"publication_dates","label":"Publication dates"}},{"value":"2026-07-24","name":"date_accepted","label":"Date Accepted","group":{"name":"publication_dates","label":"Publication dates"}},{"value":"2026-08-26","name":"date_epub","label":"Online publication date","group":{"name":"publication_dates","label":"Publication dates"}}]}}