| Lung volume does not alter the distribution of pulmonary perfusion in dependent lung in supine humans. | |
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MedLine Citation:
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PMID: 20921195 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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There is a gravitational influence on pulmonary perfusion, including in the most dependent lung, where perfusion is reduced, termed Zone 4. Studies using xenon-133 show Zone 4 behaviour, present in the dependent 4 cm at total lung capacity (TLC), affects the dependent 11 cm at functional residual capacity (FRC) and almost all the lung at residual volume (RV). These differences were ascribed to increased resistance in extra-alveolar vessels at low lung volumes although other mechanisms have been proposed. To further evaluate the behaviour of perfusion in dependent lung using a technique that directly measures pulmonary perfusion and corrects for tissue distribution by measuring regional proton density, seven healthy subjects (age = 38 ± 6 years, FEV₁ = 104 ± 7% predicted) underwent magnetic resonance imaging in supine posture. Data were acquired in the right lung during breath-holds at RV, FRC and TLC. Arterial spin labelling quantified regional pulmonary perfusion, which was normalized for regional proton density measured using a fast low-angle shot technique. The height of the onset of Zone 4 behaviour was not different between lung volumes (P = 0.23). There were no significant differences in perfusion (expressed as ml min⁻¹ g⁻¹) between lung volumes in the gravitationally intermediate (RV = 8.9 ± 3.1, FRC = 8.1 ± 2.9, TLC = 7.4 ± 3.6; P = 0.26) and dependent lung (RV = 6.6 ± 2.4, FRC = 6.1 ± 2.1, TLC = 6.4 ± 2.6; P = 0.51). However, at TLC perfusion was significantly lower in non-dependent lung than at FRC or RV (3.6 ± 3.3, 7.7 ± 1.5, 7.9 ± 2.0, respectively; P < 0.001). These data suggest that the mechanism of the reduction in perfusion in dependent lung is unlikely to be a result of lung volume related increases in resistance in extra-alveolar vessels. In supine posture, the gravitational influence on perfusion is remarkably similar over most of the lung, irrespective of lung volume. |
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Authors:
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Susan R Hopkins; Tatsuya J Arai; A Cortney Henderson; David L Levin; Richard B Buxton; G Kim Prisk |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't Date: 2010-10-04 |
Journal Detail:
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Title: The Journal of physiology Volume: 588 ISSN: 1469-7793 ISO Abbreviation: J. Physiol. (Lond.) Publication Date: 2010 Dec |
Date Detail:
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Created Date: 2010-12-02 Completed Date: 2011-04-11 Revised Date: 2011-12-21 |
Medline Journal Info:
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Nlm Unique ID: 0266262 Medline TA: J Physiol Country: England |
Other Details:
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Languages: eng Pagination: 4759-68 Citation Subset: IM |
Affiliation:
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Department of Medicine, Division of Physiology, University of California, San Diego, La Jolla, CA 92093-0623, USA. shopkins@ucsd.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Blood Flow Velocity Gravitation Humans Lung / blood supply*, physiology* Lung Compliance Magnetic Resonance Imaging Organ Size Pulmonary Circulation Supine Position |
| Grant Support | |
ID/Acronym/Agency:
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1F32-HL-078128/HL/NHLBI NIH HHS; HL-080203/HL/NHLBI NIH HHS; HL-081171/HL/NHLBI NIH HHS |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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