Document Detail

Lower exhaled nitric oxide in hypobaric than in normobaric acute hypoxia.
MedLine Citation:
PMID:  19686871     Owner:  NLM     Status:  MEDLINE    
Analysis of exhaled nitric oxide (NO) has become an accepted complementary tool in the management of inflammatory airway diseases. Previous studies have demonstrated reduced exhaled NO at altitude and ascribed their findings to hypoxia. We studied exhaled NO partial pressures (Pe(NO)) in eight healthy subjects at reduced ambient pressure down to 540 hPa (equivalent to 5000 m altitude) and at sea level, with equivalently hypoxic breathing gases (down to 11.3% O2 in N2). Pe(NO) readings were corrected for gas density effects on the instrument performance. Sea level control values for Pe(NO) at an exhaled flow of 50 mls(-1) averaged 2.4 mPa and were virtually unchanged with normobaric hypoxia down to an inspired P(O)(2) of 10.7 kPa. With the same degree of hypoxia, hypobaric Pe(NO) was 1.4 mPa. The reduction in hypobaric Pe(NO) of up to 33+/-16% (mean+/-SD) in comparison to normobaric Pe(NO), is likely to have been caused by enhanced axial back diffusion of NO because of the reduced gas density and an associated increased alveolar NO uptake to the blood.
Tryggve Hemmingsson; Dag Linnarsson
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-08-15
Journal Detail:
Title:  Respiratory physiology & neurobiology     Volume:  169     ISSN:  1878-1519     ISO Abbreviation:  Respir Physiol Neurobiol     Publication Date:  2009 Oct 
Date Detail:
Created Date:  2009-10-05     Completed Date:  2009-12-09     Revised Date:  2010-04-16    
Medline Journal Info:
Nlm Unique ID:  101140022     Medline TA:  Respir Physiol Neurobiol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  74-7     Citation Subset:  IM    
Section of Environmental Physiology, Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
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MeSH Terms
Anoxia / physiopathology*
Nitric Oxide / blood*
Oxygen / blood
Partial Pressure
Respiratory Mechanics / physiology*
Reg. No./Substance:
10102-43-9/Nitric Oxide; 7782-44-7/Oxygen
Comment In:
Respir Physiol Neurobiol. 2010 Mar 31;170(3):211-2; author reply 213-4   [PMID:  20123043 ]

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