{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T05:03:42Z","timestamp":1789621422309,"version":"build-2803163510"},"reference-count":19,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T00:00:00Z","timestamp":1789603200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Physiol."],"abstract":"<jats:sec>\n                    <jats:title>Rationale<\/jats:title>\n                    <jats:p>Patients with chronic respiratory diseases may develop clinically significant hypoxemia during commercial air travel because of reduced cabin pressure. In-flight oxygen prescription is typically guided by hypoxic challenge testing (HCT), a procedure that is time-consuming, costly, and not universally available. Several predictive equations based on sea-level physiological measurements have been proposed as alternatives. We aimed to externally validate six published predictive equations by comparing their performance with HCT in a large, heterogeneous cohort of patients with chronic respiratory diseases.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      We retrospectively analyzed all patients who underwent HCT at our center between 2016 and 2026. Sea-level arterial blood gases, pulmonary function tests, and relevant clinical data were collected. Six published predictive equations (E1\u2013E6) were used to estimate in-flight PaO\n                      <jats:sub>2<\/jats:sub>\n                      and compared with PaO\n                      <jats:sub>2<\/jats:sub>\n                      measured during HCT.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      A total of 177 patients were included: 39 (22%) with COPD, 64 (36%) with ILD, 34 (19%) with cystic fibrosis, and 40 (23%) with other chronic respiratory diseases. Significant correlations between predicted in-flight PaO\n                      <jats:sub>2<\/jats:sub>\n                      and HCT PaO\n                      <jats:sub>2<\/jats:sub>\n                      were observed (\u03c1 = 0.48 for E1 and E2 to 0.84 for E5; all\n                      <jats:italic>p<\/jats:italic>\n                      \u2264 0.001), but diagnostic performance remained limited. Across all patients, predictive equations demonstrated high specificity (76% for E2 to 98% for E6) but inadequate sensitivity (11% for E6 to 67% for E2) for identifying patients requiring supplemental oxygen. Cohen\u2019s \u03ba coefficients ranged from 0.07 (95% CI, \u22120.06 to 0.20) for E4 to 0.43 (95% CI, 0.27\u20130.59) for E2. Areas under the ROC curve ranged from 0.71 (95% CI, 0.62\u20130.81) for E4 to 0.79 (95% CI, 0.70\u20130.88) for E1.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>\n                      In this large external validation study, currently available predictive equations demonstrated insufficient diagnostic performance to safely replace HCT for determining the need for in-flight oxygen supplementation. Although several equations showed moderate to strong agreement with measured HCT PaO\n                      <jats:sub>2<\/jats:sub>\n                      , inadequate sensitivity resulted in clinically important misclassification of patients requiring supplemental oxygen. HCT should remain the reference standard for evaluating patients in whom the need for in-flight oxygen supplementation is uncertain.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fphys.2026.1946975","type":"journal-article","created":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T04:29:29Z","timestamp":1789619369000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["External validation of predictive equations for determining the need for in-flight oxygen supplementation in patients with respiratory disease"],"prefix":"10.3389","volume":"17","author":[{"given":"Murielle Emma","family":"Beaupr\u00e9","sequence":"first","affiliation":[{"name":"Service de Pneumologie, Centre Hospitalier de l\u2019Universit\u00e9 de Montr\u00e9al (CHUM), Universit\u00e9 de Montr\u00e9al","place":["Montreal, QC, Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gao Sheng","family":"Huang","sequence":"additional","affiliation":[{"name":"Service de Pneumologie, Centre Hospitalier de l\u2019Universit\u00e9 de Montr\u00e9al (CHUM), Universit\u00e9 de Montr\u00e9al","place":["Montreal, QC, Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bruno-Pierre","family":"Dub\u00e9","sequence":"additional","affiliation":[{"name":"Service de Pneumologie, Centre Hospitalier de l\u2019Universit\u00e9 de Montr\u00e9al (CHUM), Universit\u00e9 de Montr\u00e9al","place":["Montreal, QC, Canada"]},{"name":"Centre de Recherche du Centre Hospitalier de l\u2019Universit\u00e9 de Montr\u00e9al (CRCHUM)","place":["Montreal, QC, Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,9,17]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1183\/13993003.01519-2022","article-title":"European Respiratory Society\/American Thoracic Society technical statement: standardisation of the measurement of lung volumes, 2023 update","volume":"62","author":"Bhakta","year":"2023","journal-title":"Eur. 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