Effects of bronchodilators on regional lung sound distribution in patients with chronic obstructive pulmonary disease.

BACKGROUND Bronchodilators have been reported to influence regional lung ventilation in patients with chronic obstructive pulmonary disease (COPD), which may change regional lung sound distribution. Vibration response imaging (VRI) is a lung imaging system for the assessment of breath sounds. OBJECTIVE To evaluate the effects of a short-acting β2-agonist (SABA) on the regional distribution of lung sounds in COPD patients. METHODS A double-blind crossover trial was performed to compare the treatment of COPD patients with an SABA (20 µg of inhaled procaterol) versus a placebo. The percentage of regional lung sound energy [quantitative lung data (QLD)] was evaluated with VRI. VRI, spirometry, and impulse oscillometry (IOS) were performed immediately before and 30 min after SABA administration. RESULTS Ten male patients (69.6 ± 14.2 years of age, percentage predicted forced expiratory volume in 1 s: 43.8 ± 16.9%) were evaluated. The use of an SABA produced significant functional improvements in the spirometric and IOS measurements. Among the homogeneous emphysema patients (n = 7), the upper-lung QLD decreased (from 24.2 ± 5.8 to 18.8 ± 6.1%, p < 0.05) and the lower-lung QLD increased (from 37.9 ± 12.7 to 46.1 ± 14.3%, p < 0.05) following SABA inhalation. However, the significant redistribution of the regional lung QLD to the lower-lung field was not observed in 2 of the 3 inhomogeneous emphysema patients. CONCLUSION The additional use of an SABA by COPD patients improved their pulmonary function, which was accompanied by changes in regional lung air flow. The distribution of emphysematous lesions and the bronchial reactivity to SABA appeared to affect the redistribution of the lung sounds following bronchodilator administration.