Document Detail

Deep breath reversal and exponential return of methacholine-induced obstruction in asthmatic and nonasthmatic subjects.
MedLine Citation:
PMID:  14660493     Owner:  NLM     Status:  MEDLINE    
A deep breath (DB) during induced obstruction results in a transient reversal with a return to pre-DB levels in both asthmatic and nonasthmatic subjects. The time course of this transient recovery has been reported to be exponential by one group but linear by another group. In the present study, we estimated airway resistance (Raw) from measurements of respiratory system transfer impedance before and after a DB. Nine healthy subjects and nine asthmatic subjects were studied at their maximum response during a methacholine challenge. In all subjects, the DB resulted in a rapid decrease in Raw, which then returned to pre-DB levels. This recovery was well fit with a monoexponential function in both groups, and the time constant was significantly smaller in the asthmatic than the nonasthmatic subjects (11.6 +/- 5.0 and 35.1 +/- 15.9 s, respectively). Obstruction was completely reversed in the nonasthmatic subjects (pre- and postchallenge mean Raw immediately after the DB were 2.03 +/- 0.66 and 2.06 +/- 0.68 cmH2O.l-1.s, respectively), whereas in the asthmatic subjects complete reversal did not occur (2.29 +/- 0.78 and 4.84 +/- 2.64 cmH2O.l-1.s, respectively). Raw after the DB returned to postchallenge, pre-DB values in the nonasthmatic subjects (3.78 +/- 1.56 and 3.97 +/- 1.63 cmH2O.l-1.s, respectively), whereas in the asthmatic subjects it was higher but not significantly so (9.19 +/- 4.95 and 7.14 +/- 3.56 cmH2O.l-1.s, respectively). The monoexponential recovery suggests a first-order process such as airway wall-parenchymal tissue interdependence or renewed constriction of airway smooth muscle.
Andrew C Jackson; Margaret M Murphy; John Rassulo; Bartolome R Celli; Roland H Ingram
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Controlled Clinical Trial; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  96     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2004 Jan 
Date Detail:
Created Date:  2003-12-08     Completed Date:  2004-08-09     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:  137-42     Citation Subset:  IM    
Biomedical Engineering Dept., Boston Univ., 44 Cummington St., Boston, MA 02215, USA.
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MeSH Terms
Airway Obstruction / chemically induced,  drug therapy,  physiopathology*
Airway Resistance / physiology*
Anti-Asthmatic Agents / administration & dosage
Asthma / drug therapy,  physiopathology*
Bronchial Hyperreactivity / drug therapy,  physiopathology
Bronchial Provocation Tests
Bronchoconstrictor Agents / diagnostic use
Forced Expiratory Volume
Methacholine Chloride / diagnostic use
Middle Aged
Respiratory Mechanics
Grant Support
Reg. No./Substance:
0/Anti-Asthmatic Agents; 0/Bronchoconstrictor Agents; 62-51-1/Methacholine Chloride

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

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