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Small-airway obstruction, dynamic hyperinflation, and gas trapping despite normal airway sensitivity to methacholine in adults with chronic cough.
J Appl Physiol (1985). 2019 02 01; 126(2):294-304.JA

Abstract

The clinical relevance of cough during methacholine challenge in individuals with normal airway sensitivity is unknown. We compared responses of individuals with chronic cough who cough during high-dose methacholine bronchoprovocation and have normal versus increased airway sensitivity to healthy controls. Fifteen healthy participants (CONTROL) aged 26 ± 7 yr (mean ± SD) and 32 participants aged 42 ± 14 yr with chronic cough and suspected asthma completed high-dose methacholine challenge testing. Three participants who did not cough and had normal airway sensitivity were excluded. Spirometry and lung volumes were compared at the maximum response (MAX) among 1) ASTHMA [ n = 15, provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 s (FEV1) from baseline (PC20) 4.71 ± 1.37 mg/ml], 2) methacholine-induced cough with normal airway sensitivity (COUGH, n = 14, PC20 41.2 ± 18.7 mg/ml for 3 participants with a measurable PC20), and 3) CONTROL (n = 15; PC20 93.4 ± 95.4 mg/ml for 4 participants with a measurable PC20). Esophageal pressure-derived pulmonary mechanics were compared at MAX for the ASTHMA and COUGH groups. From baseline to MAX, FEV1 and forced expiratory flow between 25% and 75% of forced vital capacity decreased more in ASTHMA (-36.2 ± 3.8 %pr; -47.1 ± 6.9 %pr, respectively) than COUGH (-12.2 ± 3.0 %pr (P < 0.001); -24.7 ± 6.5 %pr (P < 0.001), respectively) and CONTROL (-13.7 ± 2.0 %pr (P < 0.001); -32.8 ± 5.4 %pr (P < 0.017), respectively). In both ASTHMA and COUGH, inspiratory capacity decreased by 500-800 ml, and functional residual capacity and residual volume increased by ~800 ml. Individuals with COUGH develop dynamic hyperinflation and gas trapping comparable to individuals with ASTHMA despite less bronchoconstriction and smaller reductions in mid-to-late expiratory flows, which leads us to believe that COUGH is a distinct phenotype. NEW & NOTEWORTHY Healthy individuals and individuals with chronic cough who demonstrate normal airway sensitivity but cough during methacholine bronchoprovocation bronchoconstrict less than individuals with mild asthma. However, those who cough and have normal airway sensitivity develop dynamic hyperinflation and gas trapping comparable to individuals with mild asthma. Thus, methacholine-induced cough with normal airway sensitivity may be clinically relevant, related to reversible small airway obstruction and preservation of the bronchodilating and/or bronchoprotective effects of deep inspirations.

Authors+Show Affiliations

Department of Medicine, Kingston Health Sciences Centre and Queen's University , Kingston, Ontario , Canada. Department of Biomedical and Molecular Sciences, Queen's University , Kingston, Ontario , Canada.Department of Medicine, Kingston Health Sciences Centre and Queen's University , Kingston, Ontario , Canada. Department of Biomedical and Molecular Sciences, Queen's University , Kingston, Ontario , Canada.Department of Medicine, Kingston Health Sciences Centre and Queen's University , Kingston, Ontario , Canada. Department of Biomedical and Molecular Sciences, Queen's University , Kingston, Ontario , Canada.Department of Medicine, Kingston Health Sciences Centre and Queen's University , Kingston, Ontario , Canada.Department of Medicine, Kingston Health Sciences Centre and Queen's University , Kingston, Ontario , Canada.Department of Biomedical and Molecular Sciences, Queen's University , Kingston, Ontario , Canada.Department of Medicine, Kingston Health Sciences Centre and Queen's University , Kingston, Ontario , Canada. Department of Biomedical and Molecular Sciences, Queen's University , Kingston, Ontario , Canada.

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

30236044

Citation

Sood, Nilita, et al. "Small-airway Obstruction, Dynamic Hyperinflation, and Gas Trapping Despite Normal Airway Sensitivity to Methacholine in Adults With Chronic Cough." Journal of Applied Physiology (Bethesda, Md. : 1985), vol. 126, no. 2, 2019, pp. 294-304.
Sood N, Turcotte SE, Wasilewski NV, et al. Small-airway obstruction, dynamic hyperinflation, and gas trapping despite normal airway sensitivity to methacholine in adults with chronic cough. J Appl Physiol. 2019;126(2):294-304.
Sood, N., Turcotte, S. E., Wasilewski, N. V., Fisher, T., Wall, T., Fisher, J. T., & Lougheed, M. D. (2019). Small-airway obstruction, dynamic hyperinflation, and gas trapping despite normal airway sensitivity to methacholine in adults with chronic cough. Journal of Applied Physiology (Bethesda, Md. : 1985), 126(2), 294-304. https://doi.org/10.1152/japplphysiol.00635.2018
Sood N, et al. Small-airway Obstruction, Dynamic Hyperinflation, and Gas Trapping Despite Normal Airway Sensitivity to Methacholine in Adults With Chronic Cough. J Appl Physiol. 2019 02 1;126(2):294-304. PubMed PMID: 30236044.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Small-airway obstruction, dynamic hyperinflation, and gas trapping despite normal airway sensitivity to methacholine in adults with chronic cough. AU - Sood,Nilita, AU - Turcotte,Scott E, AU - Wasilewski,Nastasia V, AU - Fisher,Thomas, AU - Wall,Taylar, AU - Fisher,John T, AU - Lougheed,M Diane, Y1 - 2018/09/20/ PY - 2018/9/22/pubmed PY - 2020/4/28/medline PY - 2018/9/22/entrez KW - airway obstruction KW - asthma KW - bronchial provocation tests KW - bronchoconstrictor agents KW - respiratory mechanics SP - 294 EP - 304 JF - Journal of applied physiology (Bethesda, Md. : 1985) JO - J. Appl. Physiol. VL - 126 IS - 2 N2 - The clinical relevance of cough during methacholine challenge in individuals with normal airway sensitivity is unknown. We compared responses of individuals with chronic cough who cough during high-dose methacholine bronchoprovocation and have normal versus increased airway sensitivity to healthy controls. Fifteen healthy participants (CONTROL) aged 26 ± 7 yr (mean ± SD) and 32 participants aged 42 ± 14 yr with chronic cough and suspected asthma completed high-dose methacholine challenge testing. Three participants who did not cough and had normal airway sensitivity were excluded. Spirometry and lung volumes were compared at the maximum response (MAX) among 1) ASTHMA [ n = 15, provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 s (FEV1) from baseline (PC20) 4.71 ± 1.37 mg/ml], 2) methacholine-induced cough with normal airway sensitivity (COUGH, n = 14, PC20 41.2 ± 18.7 mg/ml for 3 participants with a measurable PC20), and 3) CONTROL (n = 15; PC20 93.4 ± 95.4 mg/ml for 4 participants with a measurable PC20). Esophageal pressure-derived pulmonary mechanics were compared at MAX for the ASTHMA and COUGH groups. From baseline to MAX, FEV1 and forced expiratory flow between 25% and 75% of forced vital capacity decreased more in ASTHMA (-36.2 ± 3.8 %pr; -47.1 ± 6.9 %pr, respectively) than COUGH (-12.2 ± 3.0 %pr (P < 0.001); -24.7 ± 6.5 %pr (P < 0.001), respectively) and CONTROL (-13.7 ± 2.0 %pr (P < 0.001); -32.8 ± 5.4 %pr (P < 0.017), respectively). In both ASTHMA and COUGH, inspiratory capacity decreased by 500-800 ml, and functional residual capacity and residual volume increased by ~800 ml. Individuals with COUGH develop dynamic hyperinflation and gas trapping comparable to individuals with ASTHMA despite less bronchoconstriction and smaller reductions in mid-to-late expiratory flows, which leads us to believe that COUGH is a distinct phenotype. NEW & NOTEWORTHY Healthy individuals and individuals with chronic cough who demonstrate normal airway sensitivity but cough during methacholine bronchoprovocation bronchoconstrict less than individuals with mild asthma. However, those who cough and have normal airway sensitivity develop dynamic hyperinflation and gas trapping comparable to individuals with mild asthma. Thus, methacholine-induced cough with normal airway sensitivity may be clinically relevant, related to reversible small airway obstruction and preservation of the bronchodilating and/or bronchoprotective effects of deep inspirations. SN - 1522-1601 UR - https://www.unboundmedicine.com/medline/citation/30236044/Small_airway_obstruction_dynamic_hyperinflation_and_gas_trapping_despite_normal_airway_sensitivity_to_methacholine_in_adults_with_chronic_cough_ L2 - http://journals.physiology.org/doi/full/10.1152/japplphysiol.00635.2018?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -