Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (762 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
The exchange of oxygen and carbon dioxide between alveolar air and pulmonary capillary blood that occurs across the blood-air barrier.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Exchange, Pulmonary Gas; Gas Exchange, Pulmonary.
Where it fits in the MeSH classification
- Broader topics
- Respiratory Function Tests; Respiratory Transport
- Narrower topics
- Pulmonary Diffusing Capacity; Ventilation-Perfusion Ratio
- See also
- Blood-Air Barrier
Related concepts
- Oxygen
- Carbon Dioxide
- Blood-Air Barrier
Research landscape
PubMed indexes 21,336 records tagged with the MeSH heading “Pulmonary Gas Exchange” (counts retrieved 2026-10-31). 1,084 of them (5.1%) were published from 2020 onward, and the busiest period so far is through 1999 with 12,422 records.
Reviews account for 1,973 records (9.2%) and meta-analyses for 58. Randomized controlled trials number 1,188 (5.6%) as a share of all records on the topic.
Show the data
| Period | Records |
|---|---|
| through 1999 | 12,422 |
| 2000-2009 | 4,479 |
| 2010-2019 | 3,351 |
| 2020 onward | 1,084 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 1,973 | 9.2% |
| Meta-analyses | 58 | 0.3% |
| Randomized controlled trials | 1,188 | 5.6% |
Method: PubMed query "Pulmonary Gas Exchange"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in anatomy and physiology
Anatomy describes how body structures are built and physiology describes how they normally work, so most findings here are descriptive or mechanistic rather than evidence about treatment. Much of what is known comes from dissection, imaging, tissue studies and experiments in animals, and measurements in healthy volunteers can differ from those in people with disease or at different ages. Normal ranges vary between individuals and populations. Check whether a result was measured in people or in another species, the age and health of the participants, and the method used.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Damaged lung gas exchange function of discharged COVID-19 patients detected by hyperpolarized 129Xe MRI | 2021 | Research article Design not recorded in structured metadata | 114 | cc by PMID 33219111 · DOI · PMC7775756 |
| Hyperpolarised xenon magnetic resonance spectroscopy for the longitudinal assessment of changes in gas diffusion in IPF | 2019 | Research article Design not recorded in structured metadata | 56 | cc by PMID 30389827 · DOI · PMC6475110 |
| 129 Xe chemical shift in human blood and pulmonary blood oxygenation measurement in humans using hyperpolarized 129 Xe NMR | 2017 | Research article Design not recorded in structured metadata | 49 | cc by PMID 27062652 · DOI · PMC5363245 |
| Flow-controlled expiration improves gas exchange in anaesthetised horses undergoing orthopaedic surgery | 2026 | Research article Design not recorded in structured metadata | 2 | cc by PMID 40841837 · DOI · PMC13244185 |
Damaged lung gas exchange function of discharged COVID-19 patients detected by hyperpolarized 129Xe MRI [1]
Abstract reading summary — source excerpts
- Opening excerpt
- The recovery process of COVID-19 patients is unclear.
- Closing excerpt
- This study establishes the feasibility of localized lung function measurements in COVID-19 patients and their potential usefulness as a supplement to structural imaging.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (152 words)
The recovery process of COVID-19 patients is unclear. Some recovered patients complain of continued shortness of breath. Vasculopathy has been reported in COVID-19, stressing the importance of probing pulmonary microstructure and function at the alveolar-capillary interface. While computed tomography (CT) detects structural abnormalities, little is known about the impact of disease on lung function. 129Xe magnetic resonance imaging (MRI) is a technique uniquely capable of assessing ventilation, microstructure, and gas exchange. Using 129Xe MRI, we found that COVID-19 patients show a higher rate of ventilation defects (5.9% versus 3.7%), unchanged microstructure, and longer gas-blood exchange time (43.5 ms versus 32.5 ms) compared with healthy individuals. These findings suggest that regional ventilation and alveolar airspace dimensions are relatively normal around the time of discharge, while gas-blood exchange function is diminished. This study establishes the feasibility of localized lung function measurements in COVID-19 patients and their potential usefulness as a supplement to structural imaging.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 33219111 · DOI · PMC7775756
Hyperpolarised xenon magnetic resonance spectroscopy for the longitudinal assessment of changes in gas diffusion in IPF [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Prognosticating idiopathic pulmonary fibrosis (IPF) is challenging, in part due to a lack of sensitive biomarkers.
- Closing excerpt
- We conclude that hyperpolarised 129Xe MR spectroscopy may be sensitive to short-term changes in interstitial gas diffusion in IPF.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (98 words)
Prognosticating idiopathic pulmonary fibrosis (IPF) is challenging, in part due to a lack of sensitive biomarkers. A recent article in Thorax described how hyperpolarised xenon magnetic resonance spectroscopy may quantify regional gas exchange in IPF lungs. In a population of patients with IPF, we find that the xenon signal from red blood cells diminishes relative to the tissue/plasma signal over a 12-month time period, even when the diffusion factor for carbon monoxide is static over the same time period. We conclude that hyperpolarised 129Xe MR spectroscopy may be sensitive to short-term changes in interstitial gas diffusion in IPF.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 30389827 · DOI · PMC6475110
129 Xe chemical shift in human blood and pulmonary blood oxygenation measurement in humans using hyperpolarized 129 Xe NMR [3]
Abstract reading summary — source excerpts
- Opening excerpt
- PurposeTo evaluate the dependency of the 129 Xe-red blood cell (RBC) chemical shift on blood oxygenation, and to use this relation for noninvasive measurement of pulmonary blood oxygenation in vivo with hyperpolarized 129 Xe NMR.
- Closing excerpt
- This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (270 words)
PurposeTo evaluate the dependency of the 129 Xe-red blood cell (RBC) chemical shift on blood oxygenation, and to use this relation for noninvasive measurement of pulmonary blood oxygenation in vivo with hyperpolarized 129 Xe NMR.MethodsHyperpolarized 129 Xe was equilibrated with blood samples of varying oxygenation in vitro, and NMR was performed at 1.5 T and 3 T. Dynamic in vivo NMR during breath hold apnea was performed at 3 T on two healthy volunteers following inhalation of hyperpolarized 129 Xe.ResultsThe 129 Xe chemical shift in RBCs was found to increase nonlinearly with blood oxygenation at 1.5 T and 3 T. During breath hold apnea, the 129 Xe chemical shift in RBCs exhibited a periodic time modulation and showed a net decrease in chemical shift of ∼1 ppm over a 35 s breath hold, corresponding to a decrease of 7-10 % in RBC oxygenation. The 129 Xe-RBC signal amplitude showed a modulation with the same frequency as the 129 Xe-RBC chemical shift.ConclusionThe feasibility of using the 129 Xe-RBC chemical shift to measure pulmonary blood oxygenation in vivo has been demonstrated. Correlation between 129 Xe-RBC signal and 129 Xe-RBC chemical shift modulations in the lung warrants further investigation, with the aim to better quantify temporal blood oxygenation changes in the cardiopulmonary vascular circuit. Magn Reson Med 77:1399-1408, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 27062652 · DOI · PMC5363245
Flow-controlled expiration improves gas exchange in anaesthetised horses undergoing orthopaedic surgery [4]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundFlow-controlled expiration (FLEX) has been shown to significantly enhance oxygenation in horses under laboratory conditions.
- Closing excerpt
- ConclusionsThese results confirm previous laboratory findings, demonstrating that FLEX improves oxygenation, ventilation-perfusion matching, and respiratory mechanics compared to VCV in a large clinical population of anaesthetised horses.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (242 words)
BackgroundFlow-controlled expiration (FLEX) has been shown to significantly enhance oxygenation in horses under laboratory conditions.ObjectiveThis study aims to corroborate these findings by evaluating the effects of FLEX on gas exchange in a randomised clinical trial involving a large population of clinical horses undergoing orthopaedic surgery.Study designProspective randomised clinical trial.MethodsA total of 406 healthy adult horses scheduled for elective orthopaedic procedures were recruited for this prospective clinical trial. Horses were randomly assigned to FLEX or VCV (volume-controlled ventilation) groups in dorsal (VCV-D and FLEX-D) or lateral recumbency (VCV-L and FLEX-L). Arterial blood gases were measured at 30, 75, and 120 min post-induction to assess arterial oxygenation (arterial partial pressure of oxygen to inspired fraction of oxygen ratio, PaO2/FiO2). A global index of ventilation/perfusion matching ([PaCO2 - ETCO2]/PaCO2) was also calculated. Peak airway pressure (Ppeak) and tidal volume were measured to calculate dynamic respiratory system compliance (Cdyn). Data were compared with repeated-measures ANOVA.ResultsHorses ventilated with FLEX showed significantly higher PaO2/FiO2 (FLEX-D vs. VCV-D, 369 ± 42 vs. 198 ± 112 mmHg, p 2 - ETCO2]/PaCO2) (FLEX-D vs. VCV-D, 0.11 ± 0.03 vs. 0.18 ± 0.03, p = 0.03) in dorsal-positioned but not lateral-positioned horses.Main limitationsAnaesthesia protocols were not standardised; anaesthetists were not masked to the intervention of interest, and findings may not be generalisable to other patient populations.ConclusionsThese results confirm previous laboratory findings, demonstrating that FLEX improves oxygenation, ventilation-perfusion matching, and respiratory mechanics compared to VCV in a large clinical population of anaesthetised horses.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 40841837 · DOI · PMC13244185
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Integrative regulation of human brain blood flow [5]
- Research article Measurement of substrate oxidation during exercise by means of gas exchange measurements [6]
- Research article Measurement of the maximum oxygen uptake V̇o2max: V̇o2peak is no longer acceptable [7]
- Research article American Thoracic Society. Single-breath carbon monoxide diffusing capacity (transfer factor). Recommendations for a standard technique--1995 update [8]
- Research article The interactions of intensity, frequency and duration of exercise training in altering cardiorespiratory fitness [9]
- Research article Methodological approach to the first and second lactate threshold in incremental cardiopulmonary exercise testing [10]
References
- Li H, Zhao X, Wang Y, Lou X, Chen S, Deng H, et al.. Damaged lung gas exchange function of discharged COVID-19 patients detected by hyperpolarized 129Xe MRI. . 2021. PMID 33219111 · DOI · PMC7775756
- Weatherley ND, Stewart NJ, Chan HF, Austin M, Smith LJ, Collier G, et al.. Hyperpolarised xenon magnetic resonance spectroscopy for the longitudinal assessment of changes in gas diffusion in IPF. . 2019. PMID 30389827 · DOI · PMC6475110
- Norquay G, Leung G, Stewart NJ, Wolber J, Wild JM. 129 Xe chemical shift in human blood and pulmonary blood oxygenation measurement in humans using hyperpolarized 129 Xe NMR. . 2017. PMID 27062652 · DOI · PMC5363245
- Hopster K, Soares JHN, Levine D, Ortved K, Driessen B, Araos J. Flow-controlled expiration improves gas exchange in anaesthetised horses undergoing orthopaedic surgery. . 2026. PMID 40841837 · DOI · PMC13244185
- Willie CK, Tzeng YC, Fisher JA, Ainslie PN. Integrative regulation of human brain blood flow. J Physiol. 2014. PMID 24396059 · DOI
- Jeukendrup AE, Wallis GA. Measurement of substrate oxidation during exercise by means of gas exchange measurements. Int J Sports Med. 2005. PMID 15702454 · DOI
- Poole DC, Jones AM. Measurement of the maximum oxygen uptake V̇o2max: V̇o2peak is no longer acceptable. J Appl Physiol (1985). 2017. PMID 28153947 · DOI
- . American Thoracic Society. Single-breath carbon monoxide diffusing capacity (transfer factor). Recommendations for a standard technique--1995 update. Am J Respir Crit Care Med. 1995. PMID 8520796 · DOI
- Wenger HA, Bell GJ. The interactions of intensity, frequency and duration of exercise training in altering cardiorespiratory fitness. Sports Med. 1986. PMID 3529283 · DOI
- Binder RK, Wonisch M, Corra U, Cohen-Solal A, Vanhees L, Saner H, et al.. Methodological approach to the first and second lactate threshold in incremental cardiopulmonary exercise testing. Eur J Cardiovasc Prev Rehabil. 2008. PMID 19050438 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-31.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.