{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,28]],"date-time":"2025-11-28T11:49:54Z","timestamp":1764330594292,"version":"3.46.0"},"reference-count":36,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2025,11,27]],"date-time":"2025-11-27T00:00:00Z","timestamp":1764201600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001711","name":"Swiss National Science Foundation","doi-asserted-by":"publisher","award":["32003B 197706"],"award-info":[{"award-number":["32003B 197706"]}],"id":[{"id":"10.13039\/501100001711","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Background: In patients with pulmonary arterial hypertension or chronic thromboembolic pulmonary hypertension (summarized as pulmonary vascular disease; PVD), it is unclear whether the brain is protected against acute hypoxia and whether acute pulmonary vascular dilatation by sildenafil would influence cerebral and muscle tissue oxygenation whilst breathing normoxia or hypoxia. Methods: Adult patients with PVD underwent right heart catheterization, while cerebral and muscular tissue oxygenation and tissue hemoglobin index were measured using near-infrared spectroscopy along with arterial and mixed-venous blood gases. Participants underwent a four-stage protocol in which they were blinded to breathing either normoxia (FiO2 0.21) or normobaric hypoxia (FiO2 0.15), both before and after a single oral dose of sildenafil (50 mg) according to a randomized, cross-over design. Results: In 22 PVD patients (9 women, age 54 \u00b1 14 y) under hypoxia, mean cerebral tissue oxygenation decreased by \u22122% (95% CI \u22124 to 0%, p = 0.046), muscular tissue oxygenation by \u22121% (95% CI \u22123 to 0%, p = 0.011) and mean arterial partial pressure of oxygen by \u22122.3 kPa (95% CI \u22122.7 to \u22121.8 kPa, p &lt; 0.0001). Sildenafil improved the cerebral tissue hemoglobin index under hypoxia compared to hypoxia without sildenafil by 0.12 (95% CI 0.00 to 0.23, p = 0.049), but not the muscular tissue hemoglobin index. Conclusions: In PVD patients, acute exposure to normobaric hypoxia leads to a reduction in arterial oxygenation as well as cerebral and muscular tissue oxygenation. Sildenafil improves cerebral blood flow but has no effect on arterial, cerebral or muscular oxygenation.<\/jats:p>","DOI":"10.3390\/jcm14238407","type":"journal-article","created":{"date-parts":[[2025,11,28]],"date-time":"2025-11-28T11:19:51Z","timestamp":1764328791000},"page":"8407","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Cerebral, Muscle and Blood Oxygenation in Patients with Pulmonary Vascular Disease Whilst Breathing Normobaric Hypoxia vs. Normoxia Before and After Sildenafil: Data from a Randomised Controlled Trial"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-2182-4203","authenticated-orcid":false,"given":"Alina","family":"H\u00e4fliger","sequence":"first","affiliation":[{"name":"Pulmonology Department, University and University Hospital Zurich, 8091 Zurich, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8518-5029","authenticated-orcid":false,"given":"Michael","family":"Furian","sequence":"additional","affiliation":[{"name":"Pulmonology Department, University and University Hospital Zurich, 8091 Zurich, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3635-0515","authenticated-orcid":false,"given":"Simon R.","family":"Schneider","sequence":"additional","affiliation":[{"name":"Pulmonology Department, University and University Hospital Zurich, 8091 Zurich, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4059-5937","authenticated-orcid":false,"given":"Julian","family":"M\u00fcller","sequence":"additional","affiliation":[{"name":"Pulmonology Department, University and University Hospital Zurich, 8091 Zurich, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Meret","family":"Bauer","sequence":"additional","affiliation":[{"name":"Pulmonology Department, University and University Hospital Zurich, 8091 Zurich, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8019-7429","authenticated-orcid":false,"given":"Arcangelo F.","family":"Carta","sequence":"additional","affiliation":[{"name":"Pulmonology Department, University and University Hospital Zurich, 8091 Zurich, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8840-981X","authenticated-orcid":false,"given":"Esther I.","family":"Schwarz","sequence":"additional","affiliation":[{"name":"Pulmonology Department, University and University Hospital Zurich, 8091 Zurich, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3278-6277","authenticated-orcid":false,"given":"St\u00e9phanie","family":"Saxer","sequence":"additional","affiliation":[{"name":"Pulmonology Department, University and University Hospital Zurich, 8091 Zurich, Switzerland"},{"name":"MOVE-IT, Eastern Switzerland University of Applied Sciences, 9001 St. Gallen, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4485-1758","authenticated-orcid":false,"given":"Mona","family":"Lichtblau","sequence":"additional","affiliation":[{"name":"Pulmonology Department, University and University Hospital Zurich, 8091 Zurich, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5250-5022","authenticated-orcid":false,"given":"Silvia","family":"Ulrich","sequence":"additional","affiliation":[{"name":"Pulmonology Department, University and University Hospital Zurich, 8091 Zurich, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,11,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1350","DOI":"10.1152\/japplphysiol.00352.2017","article-title":"Human cerebral blood flow control during hypoxia: Focus on chronic pulmonary obstructive disease and obstructive sleep apnea","volume":"123","author":"Beaudin","year":"2017","journal-title":"J. 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