Document Detail

Airway distensibility in normal and asthmatic subjects and partitioning of the Fowler dead space.
MedLine Citation:
PMID:  16900236     Owner:  NLM     Status:  MEDLINE    
Anatomical dead space measured by the Fowler method (VDF) is the sum of 2 serial volume compartments (VDF = VDp1 + VDp2). VDF has been shown to increase linearly with end-inspiratory lung volume (EILV) and the gradient of the relationship (DeltaVDF) has been used as an index of airway distensibility. The aim of this study was to partition VDF into its serial compartments VDp1 and VDp2 to test the hypothesis that, given the greater distensibility of distal airways, VDp2 would demonstrate greater volume dependence than VDp1. The relationships between each measure of VD (VDF, VDp1, and VDp2) and EILV were studied in 16 healthy subjects and 16 mildly asthmatic subjects. Significant (p < 0.05) linear relationships were obtained between each measure of VD and EILV in both subject groups. Changes in VDp1 with EILV (DeltaVDp1) accounted for 78.6% +/- 5.6% (mean +/- SEM) and 72.6% +/- 6.3% of DeltaVDF in the healthy and asthmatic groups, respectively. DeltaVDp1 was greater in the healthy subjects than in asthmatic subjects (18.4 versus 13.1 mL/L, p = 0.005). We conclude that in both asthmatic and healthy subjects, the major component of DeltaVDF was DeltaVDp1 and not DeltaVDp2, as originally hypothesized. We believe our results are reflecting the degree of asynchronous airway emptying.
David P Johns; Graham Burns; David W Reid; Justin Walls; Michael Maskrey; E Haydn Walters
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Applied physiology, nutrition, and metabolism = Physiologie appliquée, nutrition et métabolisme     Volume:  31     ISSN:  1715-5312     ISO Abbreviation:  -     Publication Date:  2006 Aug 
Date Detail:
Created Date:  2006-08-10     Completed Date:  2006-10-24     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  101264333     Medline TA:  Appl Physiol Nutr Metab     Country:  Canada    
Other Details:
Languages:  eng     Pagination:  460-6     Citation Subset:  IM    
Cardio-Respiratory Research Group, School of Medicine, University of Tasmania, Hobart, Tasmania 7000, Australia.
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MeSH Terms
Asthma / physiopathology*
Exhalation / physiology
Inhalation / physiology
Lung Volume Measurements*
Respiratory Dead Space*
Respiratory System / pathology,  physiopathology*
Tidal Volume

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

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