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Lung sound analysis is useful for monitoring the therapeutic course in bronchial asthma patients

Terufumi Shimoda1, Yasushi Obase2, Yukio Nagasaka3, Hiroshi Nakano1, Reiko Kishikawa1, Tomoaki Iwanaga1

1Clinical Research Center, Fukuoka National Hospital, Fukuoka, Japan
2Department of Respiratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
3Kyoto Respiratory Center, Otowa Hospital, Kyoto, Japan

J Investig Allergol Clin Immunol 2017; Vol. 27(4)
doi: 10.18176/jiaci.0132

Background: Lung sound analysis (LSA) has been reported to be useful for predicting airway obstruction and inflammation in patients with bronchial asthma.
Objectives: We examined whether the exhalation-to-inhalation sound pressure ratio in the middle frequency range of 200-400 Hz (E/I MF) is useful for monitoring the therapeutic course in patients with asthma.
Methods: This study included 84 patients with mild to moderate asthma whose LSA data were available before and after a 1 year daily 800 μg budesonide treatment.We analyzed whether the E/I MF before and after treatment was associated with the fractional exhaled nitric oxide (FeNO) level, sputum eosinophil percentage, respiratory function, and airway hyperresponsiveness.
Results: Prior to the budesonide treatment, the E/I MF was significantly correlated with respiratory function, airway hyperresponsiveness, FeNO, and sputum eosinophil percentage. The cutoff values for the E/I MF to detect the abnormalities of respiratory function, FeNO, and sputum eosinophil percentage were 0.367, 0.358, and 0.363 respectively. The E/I MF was significantly improved in groups with budesonide-induced improvements in respiratory function or FeNO with respect to the appropriate reference value compared with groups with no improvement (odds ratios of 6.39 and 4.78, respectively). According to the multivariate analysis, patients without improvements in E/I MF had a longer smoking history (p=0.038), a lower post-treatment respiratory function (p=0.028), and a higher post-treatment FeNO (p=0.0095).
Conclusion: Similarly to respiratory function and FeNO, E/I MF based on LSA is a useful indicator for monitoring therapeutic efficacy in asthmatic patients.

Key words: Bronchial asthma, Fractional exhaled nitric oxide, Induced sputum, Inhaled corticosteroid, Lung sound analysis.