Ventilation Heterogeneity Is a Treatable Trait in Severe Asthma

Abstract

BackgroundVentilation heterogeneity is a feature of asthma and indicates small airway disease. Nuclear imaging methods assess ventilation heterogeneity which can facilitate clinical diagnosis and further our understanding of disease aetiology. ObjectiveWe sought to assess ventilation heterogeneity in severe eosinophilic asthma using ventilation/perfusion single-photon emission computed tomography (V/P SPECT), and to assess its use as an objective test of the effect of biologic treatment for ventilation defects in severe eosinophilic asthma. MethodsAdults (≥18 years) with severe asthma were recruited to participate in a cross-sectional observational study. Participants underwent a clinical assessment and V/P SPECT/CT using Technegas as the ventilation agent. Measures were repeated for a nested before-after treatment study in people with severe eosinophilic asthma commencing biologics. ResultsA total of 62 participants with severe asthma were recruited. From this, 38 participants with severe eosinophilic asthma were included in the before-after study. Ventilation heterogeneity was associated with clinical variables such as lung function impairment and significantly improved after monoclonal antibody treatment in the severe asthma group. The changes in ventilation heterogeneity correlated with change in post bronchodilator FEV1%predicted (r=-0.503, p=0.001) and post bronchodilator FEV1/FVC (r=-0.415, p=0.01). ConclusionVentilation heterogeneity is clinically significant, measurable, and treatable, which establishes ventilation heterogeneity as a treatable trait in severe asthma.