Xenon ventilation computed tomography and the management of asthma in the elderly

Background and objectiveXenon ventilation computed tomography (CT) has shown potential in assessing the regional ventilation status in subjects with asthma. The purpose of this study was to evaluate the usefulness of xenon ventilation CT in the management of asthma in the elderly. MethodsTreatment-naive asthmatics aged 65 years or older were recruited. Before initiation of medication, spirometry with bronchodilator (BD) reversibility, questionnaires to assess the severity of symptoms including a visual analogue scale (VAS), tests to evaluate cognitive function and mood, and xenon ventilation CT were performed. Xenon gas trapping (XT) on xenon ventilation CT represents an area where inhaled xenon gas was not expired and was trapped. Symptoms and lung functions were measured again after the 12-week treatment. ResultsA total of 30 elderly asthmatics were enrolled. The severity of dyspnoea measured by the VAS showed a significant correlation with the total number of areas of XT on the xenon ventilation CT taken in the pre-BD wash-out phase (r=-0.723, P<0.001). The total number of areas of XT significantly decreased after BD inhalation, and differences in the total number of areas of XT (between the pre- and post-BD wash-out phases) at baseline showed significant correlations with the per cent increases in forced expiratory volume in 1s after subsequent anti-asthma treatment (r=-0.775, P<0.001). ConclusionsXenon ventilation CT may be an objective and promising tool in the measurement of dyspnoea and prediction of the treatment response in elderly asthmatics. The present study using xenon ventilation CT, which enabled us to measure the ventilation status objectively, showed that dyspnoea and treatment response in elderly asthmatics were significantly correlated with the status of xenon gas trapping.