Document Detail

Duration of deep inspiration and subsequent airway constriction in vivo.
MedLine Citation:
PMID:  12765312     Owner:  NLM     Status:  MEDLINE    
The effects of a deep inspiration (DI) in asthmatics differ from those observed in healthy subjects. When considering the effects of a DI, an implicit assumption is that all the airways are distending at the same rate as the lung parenchyma. However, with such rapid lung inflation, the ability of contracted airways to dynamically follow the lung parenchyma was recently shown to significantly lag the lung inflation. Another potentially important variable in the response of the individual airways to a DI that has not been well studied is the duration of the DI maneuver. The current study examines the effects of increasing duration at TLC during a DI on subsequent airway caliber. In five anesthetized and ventilated mongrel dogs, after DIs of increasing duration, changes in airway size were measured over the subsequent 5-minute period using high-resolution computed tomography. Results show that the duration of the maneuver is extremely important, leading to a qualitative change in the airway response. A long DI (> or = 30 seconds) caused subsequent airway dilation, while a shorter DI (< 30 seconds) caused bronchoconstriction. The precise mechanism underlying these observations is uncertain but seems to be related to intrinsic properties within the contracted airway smooth muscle.
Robert H Brown; Wayne Mitzner
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of asthma : official journal of the Association for the Care of Asthma     Volume:  40     ISSN:  0277-0903     ISO Abbreviation:  J Asthma     Publication Date:  2003 Apr 
Date Detail:
Created Date:  2003-05-26     Completed Date:  2003-06-11     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8106454     Medline TA:  J Asthma     Country:  United States    
Other Details:
Languages:  eng     Pagination:  119-24     Citation Subset:  IM    
Department of Anesthesiology, The Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
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MeSH Terms
Airway Resistance
Asthma / physiopathology*
Bronchoconstriction / physiology*
Time Factors
Tomography, X-Ray Computed
Total Lung Capacity
Grant Support

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