Document Detail


Bronchodilation response to deep inspirations in asthma is dependent on airway distensibility and air trapping.
MedLine Citation:
PMID:  21071596     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In healthy individuals, deep inspirations (DIs) have a potent bronchodilatory ability against methacholine (MCh)-induced bronchoconstriction. This is variably attenuated in asthma. We hypothesized that inability to bronchodilate with DIs is related to reduced airway distensibility. We examined the relationship between DI-induced bronchodilation and airway distensibility in 15 asthmatic individuals with a wide range of baseline lung function [forced expired volume in 1 s (FEV(1)) = 60-99% predicted]. After abstaining from DIs for 20 min, subjects received a single-dose MCh challenge and then asked to perform DIs. The effectiveness of DIs was assessed by the ability of the subjects to improve FEV(1). The same subjects were studied by two sets of high-resolution CT scans, one at functional residual capacity (FRC) and one at total lung capacity (TLC). In each subject, the areas of 21-41 airways (0.8-6.8 mm diameter at FRC) were matched and measured, and airway distensibility (increase in airway diameter from FRC to TLC) was calculated. The bronchodilatory ability of DIs was significantly lower in individuals with FEV(1) <75% predicted than in those with FEV(1) ≥75% predicted (15 ± 11% vs. 46 ± 9%, P = 0.04) and strongly correlated with airway distensibility (r = 0.57, P = 0.03), but also with residual volume (RV)/TLC (r = -0.63, P = 0.01). In multiple regression, only RV/TLC was a significant determinant of DI-induced bronchodilation. These relationships were lost when the airways were examined after maximal bronchodilation with albuterol. Our data indicate that the loss of the bronchodilatory effect of DI in asthma is related to the ability to distend the airways with lung inflation, which is, in turn, related to the extent of air trapping and airway smooth muscle tone. These relationships only exist in the presence of airway tone, indicating that structural changes in the conducting airways visualized by high-resolution CT do not play a pivotal role.
Authors:
George Pyrgos; Nicola Scichilone; Alkis Togias; Robert H Brown
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2010-11-11
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  110     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-02-09     Completed Date:  2011-06-07     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  472-9     Citation Subset:  IM    
Affiliation:
Johns Hopkins Univ., 615 N. Wolfe St., Rm. E7614, Baltimore, MD 21205, USA.
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Adult
Airway Resistance / drug effects*
Asthma / physiopathology*
Bronchial Provocation Tests / methods*
Bronchodilator Agents / administration & dosage
Female
Humans
Inhalation / drug effects*
Male
Methacholine Chloride / administration & dosage*,  diagnostic use*
Middle Aged
Young Adult
Grant Support
ID/Acronym/Agency:
P01 HL-10342/HL/NHLBI NIH HHS; R01 HL-62698/HL/NHLBI NIH HHS; R01HL-61277/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Bronchodilator Agents; 62-51-1/Methacholine Chloride
Comments/Corrections

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


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