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Tidal airway closure during bronchoconstriction in asthma: usefulness of lung volume measurements.
MedLine Citation:
PMID:  21039204     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
Background. The presence and extent of tidal airway closure is not routinely assessed in asthma. The objective of this study was to provide a simple functional tool able to detect tidal airway closure during bronchoconstriction in asthma. Methods. In 20 subjects with mild persistent asthma, we sequentially performed the measurement of functional residual capacity (FRC) by body plethysmography (pleth) and multibreath helium dilutional technique (He) and then computed residual volume (RV) and total lung capacity (TLC) at baseline, at the end of methacholine (MCh) challenge and after bronchodilator (albuterol). Measurements and main results. Despite substantial bronchoconstriction (fall in FEV(1) = 35 ± 7%), TLC,pleth did not change following MCh challenge, but FRC,pleth because of dynamic pulmonary hyperinflation (+0.68 ± 0.54 L) and RV,pleth because of air trapping (+0.65 ± 0.37 L), invariably increased (on average by 22% and 46%, respectively). In contrast, FRC,He (and RV,He and TLC,He) could either increase, as seen in 13 subjects (Group I), or decrease, as seen in 7 subjects (Group II). Hence, the difference between FRC,pleth and FRC,He (Diff. FRC,pleth - FRC,He) was much greater in Group II (1.03 ± 0.41 L) than in Group I (0.22 ± 0.20 L) (p < .01). No functional differences were found between the two groups, including baseline PD(20)FEV(1) and absolute and percent change in forced vital capacity (FVC) at the end of the MCh challenge. Conclusions. Comparison between FRC,pleth and FRC,He is useful to identify asthmatics prone to tidal airway closure during MCh-induced bronchoconstriction and Diff. FRC,pleth - FRC,He can be used to measure the overall unventilated lung volume upstream of the airways closed at end-expiratory lung volume (EELV).
Authors:
Claudio Tantucci; Michele Guerini; Enrico Boni; Luciano Corda; Laura Pini
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Publication Detail:
Type:  Journal Article     Date:  2010-11-01
Journal Detail:
Title:  The Journal of asthma : official journal of the Association for the Care of Asthma     Volume:  48     ISSN:  1532-4303     ISO Abbreviation:  J Asthma     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-01-18     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8106454     Medline TA:  J Asthma     Country:  England    
Other Details:
Languages:  eng     Pagination:  33-40     Citation Subset:  IM    
Affiliation:
Unit of Respiratory Medicine, Department of Medical and Surgical Sciences, University of Brescia, 1st Medicina, Spedali Civili, Brescia, Italy.
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