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Changing patterns of aerosol deposition during methacholine bronchoprovocation
T G O'Riordan1, L Walser, G C Smaldone
1Department of Medicine, State University of New York, Stony Brook 11794-8172.
Chest
|May 1, 1993
Summary
Changes in airway geometry during methacholine challenges affect drug deposition sites. However, these central airway deposition shifts do not significantly determine methacholine responsiveness in individuals with or without airway hyperresponsiveness.
Area of Science:
- Pulmonary Medicine
- Respiratory Physiology
- Aerosol Science
Background:
- Airway geometry changes during bronchoprovocation testing influence drug deposition sites.
- The role of these deposition site changes in determining measured airway responsiveness remains unclear.
Purpose of the Study:
- To assess the significance of deposition sites as determinants of airway reactivity.
- To compare particle behavior in subjects with and without airway hyperresponsiveness during methacholine challenge.
Main Methods:
- Administered radiolabeled aerosols with consistent aerodynamic properties during methacholine challenge.
- Measured the specific central to peripheral deposition ratio (sC/P) before and after methacholine inhalation.
- Classified subjects as methacholine responsive (MR) or non-methacholine responsive (NMR) based on FEV1 changes.
Main Results:
- Both MR and NMR groups showed similar baseline FEV1 and initial peripheral deposition patterns (sC/P1).
- Following methacholine, all subjects exhibited a significant shift towards central airway deposition (sC/P2).
- The observed shift to central deposition during bronchoprovocation testing did not significantly differentiate between MR and NMR groups.
Conclusions:
- Preferential deposition in central airways occurs universally during bronchoprovocation testing.
- Changes in deposition sites during methacholine challenge do not appear to be a primary determinant of methacholine responsiveness.