title: Unlocking the quiet zone: the small airway asthma phenotype.
abstract: The small airways in the distal lung have been called the quiet zone because they are difficult to assess and treat in patients with asthma who have disproportionate impairment of small airway function. Evidence is accumulating to support a distinct clinical phenotype for patients with asthma who have impaired small airway function. The small airway asthma phenotype, which is prevalent in patients at all steps of management guidelines, seems to be associated with poor disease control. Alternatively, small airway dysfunction might be a sensitive indicator of early disease rather than a phenotype. Conventional coarse-particle inhalers, which emit particles larger than 2 μm, might not address persistent small airway dysfunction in patients with asthma. To target the entire lung with extra-fine particle formulations (smaller than 2 μm) of inhaled corticosteroids alone or in combination with long-acting β-agonists might result in improved long-term asthma control along with a commensurate improvement in small airway function. Prospective randomised controlled trials with extra-fine-particle inhaled drugs are now needed for patients with the small airway asthma phenotype.
authors.affiliation: Scottish Centre for Respiratory Research, Ninewells Hospital and Medical School, Dundee, UK. Electronic address: b.j.lipworth@dundee.ac.uk.
authors.forename: Brian
authors.initials: B
authors.lastname: Lipworth
authors.affiliation: Scottish Centre for Respiratory Research, Ninewells Hospital and Medical School, Dundee, UK.
authors.forename: Arvind
authors.initials: A
authors.lastname: Manoharan
authors.affiliation: Scottish Centre for Respiratory Research, Ninewells Hospital and Medical School, Dundee, UK.
authors.forename: William
authors.initials: W
authors.lastname: Anderson
mesh_terms: D000280:Administration, Inhalation; D018927:Anti-Asthmatic Agents / Q000008:administration & dosage*; D001249:Asthma / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D001980:Bronchi / Q000002:abnormalities*; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D010641:Phenotype
chemical_list: D018927:Anti-Asthmatic Agents