Document Detail

Ventilatory response to continuous incremental changes in respiratory resistance in patients with mild asthma.
MedLine Citation:
PMID:  8769505     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Conflicting results from previous studies on the effect of bronchial challenge on ventilatory patterns in asthmatics may be due to airflow obstruction present before induction of bronchospasm onset, as well as the different degrees of bronchoconstriction induced. PURPOSE AND METHODS: We examined the ventilatory response to stepwise increments in respiratory resistance (Rrs) induced by continuous methacholine inhalation in eight patients with mild stable asthma without airway obstruction and eight normal subjects. Methacholine was inhaled continuously during tidal breathing until a nearly two-fold increase in Rrs was observed. Respiratory parameters, including tidal volume (VT), respiratory frequency (f), inspiratory ventilation (VI), mean inspiratory flow (VT/TI), and duty ratio (TI/TT), were measured simultaneously by respiratory inductive plethysmograph (RIP). Arterial oxygen saturation (SaO2) was examined by pulse oximetry. The end-tidal CO2 fraction (FETCO2) was measured with a rapid-response infrared analyzer at the mouthpiece. RESULTS: Rrs, SaO2, FETCO2, and respiratory parameters, measured after saline solution inhalation, were not different between the two groups. Inhaled methacholine first decreased and then increased VI in both groups. However, changes in VI occurred earlier and to a greater extent in asthmatics than in normal subjects. At 200% Rrs (percent control), %VI was greater in asthmatics than in normal subjects (p<0.005) because of significant differences in %VT and %VT/TI between the two groups. CONCLUSION: For a given degree of bronchoconstriction, the ventilatory response was more rapid and greater in patients with mild stable asthma without airway obstruction than in normal subjects. The different response to bronchial challenge between the two groups may be due to different increases in drive due to irritant receptor stimulation.
K Fujimori; M Satoh; M Arakawa
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Chest     Volume:  109     ISSN:  0012-3692     ISO Abbreviation:  Chest     Publication Date:  1996 Jun 
Date Detail:
Created Date:  1996-10-03     Completed Date:  1996-10-03     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0231335     Medline TA:  Chest     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1525-31     Citation Subset:  AIM; IM    
Department of Medicine (II), Niigata University School of Medicine, Japan.
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MeSH Terms
Airway Resistance
Asthma / blood,  physiopathology*
Bronchial Provocation Tests
Methacholine Chloride / administration & dosage
Oxygen / blood
Respiratory Mechanics*
Reg. No./Substance:
62-51-1/Methacholine Chloride; 7782-44-7/Oxygen

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

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