Document Detail


Methacholine responsiveness using the raised volume forced expiration technique in infants.
MedLine Citation:
PMID:  9154874     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Infant lung function can be assessed with the tidal volume "squeeze" technique or, over an extended volume range, with the newer raised volume forced expiration technique (RVFET). We assessed methacholine responsiveness in 11 infants, measuring both maximal expiratory flow at functional residual capacity (V.max,FRC)with the tidal volume technique, and forced expiratory volume/time (FEV(t)) with RVFET. We used a standard methodology for the former. FEV(t) was measured by inflating the infant's lungs to 20 cm H2O and forcing expiration using a jacket setup to transmit a pressure of 20 cm H2O to the airway. Lung function was measured at baseline and after methacholine inhalations, increasing from 0.1 g/L to 10 g/L in half log dosage increments (DI). The provocative concentrations (PC) of methacholine leading to a 40% fall in V.max,FRC and a 15 or 20% fall in FEV(t) were calculated. The mean provocative concentration of methacholine required to produce a 40% fall in V.max,FRC was less than that required to produce a 20% fall in FEV0.5 by 0.39 DI (95% CI, -0.60 to 1.38) and less than that required to produce a 20% fall in FEV0.75 by 0.42 DI (95%, CI, -0.54 to 1.39). Similarly, the provocative concentration of methacholine required to produce a 40% fall in V.max,FRC was less than that required to produce a 15% fall in FEV0.5 by 0.14 DI (95% CI, -0.99 to 1.28) or a 15% fall in FEV0.75 by 0.13 DI (95% CI, -0.80 to 1.08), but the differences were small and not significant. Despite these differences the agreement between the two methods was good, and bronchoconstriction was not attenuated by the forced inspiration delivered by the raised volume maneuver. We conclude that the raised volume forced expiration technique is able to detect methacholine-induced bronchoconstriction.
Authors:
M J Hayden; S G Devadason; P D Sly; J H Wildhaber; P N LeSouëf
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  155     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  1997 May 
Date Detail:
Created Date:  1997-06-03     Completed Date:  1997-06-03     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1670-5     Citation Subset:  AIM; IM    
Affiliation:
Department of Respiratory Medicine, Princess Margaret Hospital, Perth, Western Australia.
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MeSH Terms
Descriptor/Qualifier:
Bronchial Provocation Tests
Bronchoconstriction / drug effects*
Forced Expiratory Flow Rates / drug effects
Forced Expiratory Volume / drug effects
Humans
Infant
Methacholine Chloride / diagnostic use*
Respiratory Function Tests / methods*
Respiratory Sounds / physiopathology*
Vital Capacity / drug effects
Chemical
Reg. No./Substance:
62-51-1/Methacholine Chloride

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


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