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Targeting the small airways with dry powder adenosine: a challenging concept
Background: Small-particle inhaled corticosteroids (ICS) provide a higher small airway deposition than large-particle ICS. However, we are still not able to identify asthma patients who will profit most from small-particle treatment. Objective: We aimed to identify these patients by selectively chal...
Autores principales: | , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Taylor & Francis
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5642194/ https://www.ncbi.nlm.nih.gov/pubmed/29057065 http://dx.doi.org/10.1080/20018525.2017.1369328 |
Sumario: | Background: Small-particle inhaled corticosteroids (ICS) provide a higher small airway deposition than large-particle ICS. However, we are still not able to identify asthma patients who will profit most from small-particle treatment. Objective: We aimed to identify these patients by selectively challenging the small and large airways. We hypothesized that the airways could be challenged selectively using small- and large-particle adenosine, both inhaled at a high and a low flow rate. Design: In this cross-over study 11 asthma subjects performed four dry powder adenosine tests, with either small (MMAD 2.7 µm) or large (MMAD 6.0 µm) particles, inhaled once with a low flow rate (30 l min(–1)) and once with a high flow rate (60 l min(–1)). Spirometry and impulse oscillometry were performed after every bronchoprovocation step. We assumed that FEV(1) reflects the large airways, and FEF(25–75%), R5-R20 and X5 reflect the small airways. Results: The four adenosine tests were not significantly different with respect to the threshold values of FEV(1) (p = 0.12), FEF(25–75%) (p = 0.37), R5-R20 (p = 0.60) or X5 (p = 0.46). Both small- and large-particle adenosine induced a response in the small airways in the majority of the tests. Conclusions: In contrast to our hypothesis, all four adenosine tests provoked a response in the small airways and we could not identify different large- or small-airway responders. Interestingly, even the test with large particles and a high flow rate induced a small-airway response, suggesting that selective challenging of the small airways is not necessary. Future studies should investigate the relation between particle deposition and the site of an airway response. |
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