Effects of Bronchodilators on Regional Lung Sound Distribution in Patients with Chronic Obstructive Pulmonary Disease

Abstract

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.

Regional Lung Sound Asynchrony in Chronic Obstructive Pulmonary Disease Patients

“…Since we did not find significant correlations between either AS or age in the control group, we believe that the difference in age between healthy subjects and COPD patients did not influence the higher AS in COPD patients. Furthermore, we did not define a washout time for 19 patients with bronchodilator treatment, although bronchodilator use for COPD patients was reported to change the distribution of the lung sounds [12]. However, we revealed positive correlations between AS and heterogeneity of emphysema distribution in 22 patients with no bronchodilator treatments.…”

“…Although there are many investigations regarding lung sound amplitude, transmission, distribution, or adventitious sounds [3,4,5,6,7,10,12,14,20,21], there are only a few reports to study lung sound asynchrony [8,9,13,15]. Wang et al [9] revealed that asynchrony between the left and right lung in asthma exacerbations was significantly reduced after clinical improvement.…”

“…Lung sounds were recorded using the VRIxp System (Deep Breeze, Ltd., Or-Akiva, Israel) during deep and regular breaths as previously described [5,6,7,8,9,10,12,13,14,15]. Prior to lung sound recordings, a physician examined all patients using a stethoscope.…”

“…Three CT slices were selected for each subject; the upper cranial slice was obtained 1 cm above the upper margin of the aortic arch, the middle slice was obtained 1 cm below the carina, and the lower caudal slice was obtained 1 cm below the right inferior pulmonary vein. CT images were then analyzed using a semiautomatic image processing program (ImageJ version 1.40g, a public domain Java image-processing program available at http://rsb.info.nih.gov/ij/) as previously described [12]. Low-attenuation areas (LAA) between -950 and -1,024 HU were identified as emphysema, and the percentage of the LAA for the entire lung area (%LAA) was calculated for 6 parts; i.e.…”

“…Vibration response imaging (VRI) is an acoustic lung imaging system that records and displays breath sound energy distribution as a dynamic grey-scale image [5,6,7,8,9,10,11,12,13]. Using VRI, Wang et al [14] reported that in subjects with obstructive airway diseases such as asthma and COPD, dynamic images of the lung showed asynchrony within each lung and between lungs.…”