Lung sound analysis can be an index of the control of bronchial asthma

• Main Authors: Terufumi Shimoda, Yasushi Obase, Yukio Nagasaka, Hiroshi Nakano, Reiko Kishikawa, Tomoaki Iwanaga
• Format: Article
• Language: English
• Published: Elsevier 2017-01-01
• Series: Allergology International
• Subjects: Adherence; Airway inflammation; Bronchial asthma; Expiration-to-inspiration lung sound power ratio at low frequencies (E/I LF); Lung sound analysis
• Online Access: http://www.sciencedirect.com/science/article/pii/S1323893016300557

Background: We assessed whether lung sound analysis (LSA) is a valid measure of airway obstruction and inflammation in patients with bronchial asthma during treatment with inhaled corticosteroids (ICSs). Methods: 63 good adherence patients with bronchial asthma and 18 poor adherence patients were examined by LSA, spirometry, fractional exhaled nitric oxide (FeNO), and induced sputum. The expiration-to-inspiration lung sound power ratio at low frequencies between 100 and 200 Hz (E/I LF) obtained by LSA was compared between healthy volunteers and bronchial asthma patients. Next, post-ICS treatment changes were compared in bronchial asthma patients between the good adherence patients and the poor adherence patients. Results: E/I LF was significantly higher in bronchial asthma patients (0.62 ± 0.21) than in healthy volunteers (0.44 ± 0.12, p < 0.001). The good adherence patients demonstrated a significant reduction in E/I LF from pre-treatment to post-treatment (0.55 ± 0.21 to 0.46 ± 0.16, p = 0.002), whereas the poor adherence patients did not show a significant change. The decrease of E/I LF correlated with the improvement of FEV1/FVC ratio during the ICS treatment (r = −0.26, p = 0.04). The subjects with higher pre-treatment E/I LF values had significantly lower FEV1/FVC and V50,%pred (p < 0.001), and significantly higher FeNO and sputum eosinophil percentages (p = 0.008 and p < 0.001, respectively). Conclusions: The E/I LF measurement obtained by LSA is useful as an indicator of changes in airway obstruction and inflammation and can be used for monitoring the therapeutic course of bronchial asthma patients.