Document Detail

Parasympathetic airway response and heart rate variability before and at the end of methacholine challenge.
MedLine Citation:
PMID:  15653958     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The autonomic nervous system plays a primary role in regulating airway caliber, and its dysfunction is likely to contribute to the pathogenesis of airways diseases. Moreover, some findings support the hypothesis that autonomic dysfunction and/or dysregulation contributes to the pathogenesis of airway hyperresponsiveness (AHR). Heart rate variability (HRV) spectral analysis allows identifying noninvasively perturbations of the autonomic system. PURPOSES: We tested the relationship between AHR and cardiac parasympathetic tone assessed by HRV spectral analysis in patients submitted to a diagnostic methacholine bronchial challenge (MBC). METHODS: Fifteen women and 38 men (age range, 18 to 56 years) participated in the study. The principal indications for MBC were suspected asthma, chronic cough, unexplained exercise-induced dyspnea, or cough. The R-R intervals were continuously recorded during the MBC. Autoregressive method was performed on two series of 256 R-R intervals extracted before and after the MBC to obtain low-frequency (LF) and high-frequency (HF) components. RESULTS: The MBC distinguished 29 subjects without airway responsiveness (R-) and 24 responder or hyperresponsive subjects (R+): mean provocative dose of methacholine causing a 20% reduction in mean (+/- SD) FEV1 of 467 +/- 351 microg (range, 70 to 1,426 microg). The HF component expressed in normalized units (n.u.) [the index of parasympathetic modulation] was significantly higher in R+ than in R- at baseline, before MBC (21 +/- 21 n.u. vs 11 +/- 9 n.u., p < 0.05). Interestingly, R+ showed a significant increase of HF component after MBC (243 +/- 30 to 567 +/- 620 ms2 and 21 +/- 21 to 34 +/- 30 n.u., p < 0.01). For all subjects, HF (n.u.) calculated at baseline and after MBC were significantly influenced by the bronchial responsiveness (r2 = -0.28 and -0.51, respectively; p < 0.001). CONCLUSION: In summary, we found that R+ had a significantly higher parasympathetic tone than R- at baseline, and that R+ showed a significant increase in cardiac reactivity after bronchial challenge. These findings demonstrate that the autonomic nervous system, which contributes to the pathogenesis of AHR, is closely linked to cardiac modulation.
Aurélien Pichon; Claire de Bisschop; Véronique Diaz; André Denjean
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Chest     Volume:  127     ISSN:  0012-3692     ISO Abbreviation:  Chest     Publication Date:  2005 Jan 
Date Detail:
Created Date:  2005-01-17     Completed Date:  2005-02-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0231335     Medline TA:  Chest     Country:  United States    
Other Details:
Languages:  eng     Pagination:  23-9     Citation Subset:  AIM; IM    
Service d'Explorations Fonctionnelles, Physiologie Respiratoire et de l'Exercice, Pôle Coeur-Poumons, CHU de Poitiers, France.
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MeSH Terms
Asthma / physiopathology
Bronchial Hyperreactivity / physiopathology*
Bronchial Provocation Tests*
Heart / innervation*
Heart Rate
Methacholine Chloride / diagnostic use
Middle Aged
Parasympathetic Nervous System / physiology*
Parasympathomimetics / diagnostic use
Reg. No./Substance:
0/Parasympathomimetics; 62-51-1/Methacholine Chloride

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