Document Detail

Collateral ventilation and gas exchange during airway occlusion in the normal human lung.
MedLine Citation:
PMID:  8442584     Owner:  NLM     Status:  MEDLINE    
The effectiveness of collateral ventilation in maintaining alveolar gas tensions in obstructed lung segments was investigated using fiberoptic bronchoscopy to place an occluding catheter-tip balloon in selected lobar and segmental bronchi in supine normal human subjects. Gas tensions from beyond the occlusion were measured with a respiratory mass spectrometer. Collateral ventilation is known to be minimal between lobes; therefore, values measured in obstructed lobes provide a control. No significant difference was found between the partial pressures of oxygen or carbon dioxide measured in obstructed lobes and in obstructed segments. In both cases respiratory gas tensions approached reported values for mixed venous levels. The time taken to attain a steady state of gas composition in the obstructed lung was rapid (approximately 50 s), and it was no different for lobes and segments. In addition, collateral ventilation was assessed by measuring the amount of helium reaching occluded lobes and segments when subjects breathed a mixture of 21% oxygen and 79% helium. The rate of rise in helium concentration was less than 1%/min in both lobes and segments, a figure that may be explained by delivery of helium in recirculated blood rather than by collateral ventilation. We conclude that intersegmental collateral ventilation has a negligible role in the maintenance of alveolar gas tensions in supine normal humans during tidal breathing.
N W Morrell; C M Roberts; T Biggs; W A Seed
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American review of respiratory disease     Volume:  147     ISSN:  0003-0805     ISO Abbreviation:  Am. Rev. Respir. Dis.     Publication Date:  1993 Mar 
Date Detail:
Created Date:  1993-04-01     Completed Date:  1993-04-01     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370523     Medline TA:  Am Rev Respir Dis     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  535-9     Citation Subset:  AIM; IM    
Department of Medicine, Charing Cross and Westminster Medical School, London, United Kingdom.
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MeSH Terms
Airway Obstruction / etiology,  physiopathology*
Bronchoscopy / methods
Carbon Dioxide / physiology
Fiber Optic Technology
Oxygen / physiology
Partial Pressure
Pulmonary Gas Exchange / physiology*
Reference Values
Respiration / physiology*
Tidal Volume / physiology
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen
Comment In:
Am J Respir Crit Care Med. 1994 Feb;149(2 Pt 1):553-4   [PMID:  8306060 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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