Document Detail

Morning-to-evening variation in exercise-induced bronchospasm.
MedLine Citation:
PMID:  12170263     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Exercise is one of the most common triggers of asthmatic symptoms. Many factors, including hyperventilation, determine the prevalence and severity of exercise-induced bronchospasm (EIB). However, the influence of time of day has not been adequately described. OBJECTIVE: We sought to compare morning and evening EIB and minute ventilation during exercise (VE). METHODS: Twenty-two patients with stable asthma and 12 control subjects underwent exercise challenge at 7 am and 6 pm. The time of the first challenge was randomly assigned; the second challenge was performed within 1 week of the first. The primary outcomes were EIB intensity (maximum fall in FEV(1)) and VE. RESULTS: The asthma group exhibited lower EIB values in the morning: 14.8% +/- 3.7% at 7 am vs 21.4% +/- 4.2% at 6 pm (P =.004)-ie, 0.37 +/- 0.09 L vs 0.53 +/- 0.10 L, respectively (P =.002). VE was higher at 7 am (55.4 +/- 4.7 L/min) than at 6 pm (52.4 +/- 4.3 L/min; P =.03). Baseline FEV(1) increased from 2.33 +/- 0.13 L (morning) to 2.49 +/- 0.15 L (evening; P =.04), and a significant correlation between baseline FEV(1) and EIB was found in the evening (r = +0.5; P =.049) but not in the morning. Post-exercise FEV(1) was similar at 7 am (1.96 +/- 0.13 L) and 6 pm (1.97 +/- 0.14 L). For the control group, no changes were detected in FEV(1) fall or VE. CONCLUSION: Baseline airway caliber contributes to the mechanisms of the morning-to-evening EIB enhancement.
Elcio O Vianna; Luiz C Boaventura; João Terra-Filho; Gilberto Y Nakama; José A B Martinez; Richard J Martin
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of allergy and clinical immunology     Volume:  110     ISSN:  0091-6749     ISO Abbreviation:  J. Allergy Clin. Immunol.     Publication Date:  2002 Aug 
Date Detail:
Created Date:  2002-08-09     Completed Date:  2002-09-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  1275002     Medline TA:  J Allergy Clin Immunol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  236-40     Citation Subset:  AIM; IM    
Department of Medicine, University of São Paulo Medical School at Ribeirão Preto, Av. Bandeirantes, 3900 Ribeirão Preto--SP 14048 900, Brazil.
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MeSH Terms
Activities of Daily Living*
Asthma, Exercise-Induced / physiopathology*
Bronchial Spasm / physiopathology
Exercise Test
Forced Expiratory Volume
Prospective Studies
Pulmonary Ventilation
Time Factors

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