Therapeutische Implikationen der Diagnose „small airway disease“

Small airway disease (SAD) is a significant indicator for the severity of obstructive airway diseases and profoundly influences treatment strategies. Conventional lung function measurements, such as FEV1 and FEV1/FVC, are insufficient for evaluating the effects of inhalation treatment on the small airways as they primarily reflect the large airways. Therefore, alternative assessment methods, such as the single-breath nitrogen washout test, forced oscillometry and imaging techniques, such as high-resolution computed tomography (CT) or magnetic resonance imaging (MRI) with hyperpolarized helium or xenon are necessary for assessment of the small airways. A major problem is that many inhalation therapies do not effectively reach the small airways. The efficacy of these therapies is highly dependent on particle size, with smaller particles (mass median aerodynamic diameter, MMAD ≤ 2 μm) penetrating the peripheral lungs more effectively, resulting in better distribution and effects. Traditional inhalers, such as pressurized metered dose inhalers (pMDI) and dry powder inhalers (DPI), often produce particles that are too large leading to insufficient deposition in the small airways and unwanted systemic effects. Advances in the development of inhalers that emit small particles at low velocity have improved particle distribution within the lungs. In asthma patients the data indicate that aerosols with small particles enable better control and quality of life. The combination of beclomethasone/formoterol, administered with a hydrofluoroalkane (HFA)-driven pMDI, improves both SAD markers and asthma control. For chronic obstructive pulmonary disease (COPD) the small airways are a crucial therapeutic target. Modern bronchodilators and ultrafine particles have proven effective in treating SAD and improving lung function. Systemic treatment with biologics could also play a crucial role in treating SAD by affecting the entire lung. Ongoing research in this area aims to identify optimal treatment approaches.