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Respir Physiol Neurobiol. 2013 Dec 1;189(3):506-12. doi: 10.1016/j.resp.2013.08.015. Epub 2013 Aug 29.

Deep inspiration volume and the impaired reversal of bronchoconstriction in asthma.

Author information

1
Medical School, University of Sydney, NSW 2006, Australia.

Abstract

It is unclear whether the failure to reverse bronchoconstriction with deep inspiration (DI) in asthma is due to reduced maximal dilatation of the DI. We compared the effect of different DI volumes on maximal dilatation and reversal of bronchoconstriction in nine asthmatics and ten non-asthmatics. During bronchoconstriction, subjects took DI to 40%, 70% and 100% inspiratory capacity, on separate days. Maximal dilatation was measured as respiratory system resistance (Rrs) at end-inspiration and residual dilatation as Rrs at end-expiration, both expressed as percent of Rrs at end-tidal expiration prior to DI. DI volume was positively associated with maximal dilatation in non-asthmatics (ANOVA p=0.055) and asthmatics (p=0.023). DI volume was positively associated with residual dilatation in non-asthmatics (p=0.004) but not in asthmatics (p=0.53). The degree of maximal dilatation independently predicted residual dilatation in non-asthmatics but not asthmatics. These findings suggest that the failure to reverse bronchoconstriction with DI in asthma is not due to reduced maximal dilatation, but rather due to increased airway narrowing during expiration.

KEYWORDS:

Airway hyperresponsiveness; Airway physiology; Asthma; Deep inspiration

PMID:
23994826
DOI:
10.1016/j.resp.2013.08.015
[Indexed for MEDLINE]

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