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Avoiding deep inspirations increases the maximal response to methacholine without altering sensitivity in non-asthmatics.
Respir Physiol Neurobiol. 2010 Sep 30; 173(2):157-63.RP

Abstract

Airway hyperresponsiveness is characterised by a leftward shift of the dose-response curve (DRC) and an increase in the maximal response. Deep inspiration (DI) avoidance increases responsiveness in non-asthmatic, but not asthmatic, subjects. The aim was to determine the effect of DI avoidance on the sensitivity and maximal response of the FEV(1) DRC to methacholine. Thirteen non-asthmatic and ten asthmatic subjects underwent a standard cumulative high-dose methacholine challenge (0.1-200μmol). Subsequently, on separate days, increasing single doses of methacholine were administered after 10min of DI avoidance. A sigmoidal equation was fitted to the data to obtain values for α, the position constant, as a measure of sensitivity. The fall in FEV(1) at the highest common dose was used as a measure of the maximal response. The change in flow at 40% control vital capacity on the maximal (V˙40m) and partial (V˙40p) curves were calculated from the first manoeuvre after methacholine and the ratio of the values for V˙40m and V˙40p was calculated as a measure of the bronchodilator effect of DI (BD(DI)). In non-asthmatic subjects, avoiding DI increased the maximum fall in FEV(1) at the highest common dose (p=0.0001) but did not alter α (p=0.75). Avoiding DI before challenge did not alter BD(DI) (p=0.13). DI avoidance had no effect on airway responsiveness in asthmatic subjects. In non-asthmatic subjects, DI avoidance increases airway responsiveness by increasing the maximal response, but does not alter the sensitivity, suggesting that the loss of the effect of DI in asthma contributes to excessive bronchoconstriction.

Authors+Show Affiliations

Woolcock Institute of Medical Research, PO Box M77 Missenden Road, Sydney, NSW 2050, Australia. dcha7069@woolcock.org.auNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

20688195

Citation

Chapman, David G., et al. "Avoiding Deep Inspirations Increases the Maximal Response to Methacholine Without Altering Sensitivity in Non-asthmatics." Respiratory Physiology & Neurobiology, vol. 173, no. 2, 2010, pp. 157-63.
Chapman DG, King GG, Berend N, et al. Avoiding deep inspirations increases the maximal response to methacholine without altering sensitivity in non-asthmatics. Respir Physiol Neurobiol. 2010;173(2):157-63.
Chapman, D. G., King, G. G., Berend, N., Diba, C., & Salome, C. M. (2010). Avoiding deep inspirations increases the maximal response to methacholine without altering sensitivity in non-asthmatics. Respiratory Physiology & Neurobiology, 173(2), 157-63. https://doi.org/10.1016/j.resp.2010.07.011
Chapman DG, et al. Avoiding Deep Inspirations Increases the Maximal Response to Methacholine Without Altering Sensitivity in Non-asthmatics. Respir Physiol Neurobiol. 2010 Sep 30;173(2):157-63. PubMed PMID: 20688195.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Avoiding deep inspirations increases the maximal response to methacholine without altering sensitivity in non-asthmatics. AU - Chapman,David G, AU - King,Gregory G, AU - Berend,Norbert, AU - Diba,Chantale, AU - Salome,Cheryl M, Y1 - 2010/08/03/ PY - 2010/03/29/received PY - 2010/07/27/revised PY - 2010/07/27/accepted PY - 2010/8/7/entrez PY - 2010/8/7/pubmed PY - 2010/12/29/medline SP - 157 EP - 63 JF - Respiratory physiology & neurobiology JO - Respir Physiol Neurobiol VL - 173 IS - 2 N2 - Airway hyperresponsiveness is characterised by a leftward shift of the dose-response curve (DRC) and an increase in the maximal response. Deep inspiration (DI) avoidance increases responsiveness in non-asthmatic, but not asthmatic, subjects. The aim was to determine the effect of DI avoidance on the sensitivity and maximal response of the FEV(1) DRC to methacholine. Thirteen non-asthmatic and ten asthmatic subjects underwent a standard cumulative high-dose methacholine challenge (0.1-200μmol). Subsequently, on separate days, increasing single doses of methacholine were administered after 10min of DI avoidance. A sigmoidal equation was fitted to the data to obtain values for α, the position constant, as a measure of sensitivity. The fall in FEV(1) at the highest common dose was used as a measure of the maximal response. The change in flow at 40% control vital capacity on the maximal (V˙40m) and partial (V˙40p) curves were calculated from the first manoeuvre after methacholine and the ratio of the values for V˙40m and V˙40p was calculated as a measure of the bronchodilator effect of DI (BD(DI)). In non-asthmatic subjects, avoiding DI increased the maximum fall in FEV(1) at the highest common dose (p=0.0001) but did not alter α (p=0.75). Avoiding DI before challenge did not alter BD(DI) (p=0.13). DI avoidance had no effect on airway responsiveness in asthmatic subjects. In non-asthmatic subjects, DI avoidance increases airway responsiveness by increasing the maximal response, but does not alter the sensitivity, suggesting that the loss of the effect of DI in asthma contributes to excessive bronchoconstriction. SN - 1878-1519 UR - https://www.unboundmedicine.com/medline/citation/20688195/Avoiding_deep_inspirations_increases_the_maximal_response_to_methacholine_without_altering_sensitivity_in_non_asthmatics_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1569-9048(10)00274-0 DB - PRIME DP - Unbound Medicine ER -