Targeting the small airways asthma phenotype: if we can reach it, should we treat it?
Ann Allergy Asthma Immunol. 2013 Apr;110(4):233-9. doi: 10.1016/j.anai.2013.02.009. Lipworth B. Asthma and Allergy Research Group, Ninewells Hospital and Medical School, Dundee, Scotland.
OBJECTIVE: To review the available methods of evaluating the small airways disease in asthma and the therapeutic strategies to achieve better control using emerging extrafine particle inhaler technologies.DATA SOURCES:
The PubMed, MEDLINE (Ebsco), Scirus, Scopus, and Google Scholar databases were all scanned with Cross-search using the following keywords: asthma, small airways, hydrofluoroalkane 134a, extrafine particle, inhaled corticosteroid, long-acting β-agonist, spirometry, impulse oscillometry, nitrogen washout, exhaled nitric oxide, airway hyperresponsiveness, and adrenal suppression.
STUDY SELECTION: Key clinical studies considered to being relevant to the topic under review were evaluated.
RESULTS: There is an unmet need in current asthma guidelines for those individuals who exhibit the small airways asthma phenotype with a preserved forced expiratory volume in 1 second but abnormal forced midexpiratory flow and peripheral airway resistance, which tends to be associated with poorer control. Extrafine hydrofluoroalkane solution formulations of inhaled corticosteroid either alone or in combination with long-acting β-agonist may improve small airways outcomes and associated control.
CONCLUSION: From a pragmatic perspective, it makes sense to try to deliver asthma treatment to more of the lung to improve clinical outcomes, especially in patients who exhibit the small airways asthma phenotype.