Lung Sound Analysis Provides A Useful Index For Both Airway Narrowing And Airway Inflammation In Patients With Bronchial Asthma
Received 23 May 2019
Accepted for publication 18 September 2019
Published 4 October 2019 Volume 2019:12 Pages 323—329
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Melinda Thomas
Peer reviewer comments 2
Editor who approved publication: Dr Amrita Dosanjh
Terufumi Shimoda,1,2 Yasushi Obase,3 Yukio Nagasaka,4 Reiko Kishikawa,2 Sadahiro Asai1
1Department of Allergy, San Remo Rehabilitation Hospital, Sasebo, Japan; 2Department of Allergy, Clinical Research Center, Fukuoka National Hospital, Fukuoka, Japan; 3Department of Respiratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; 4Department of Respiratory Medicine, Kyoto Respiratory Center, Otowa Hospital, Kyoto, Japan
Correspondence: Terufumi Shimoda
Department of Allergy, San Remo Rehabilitation Hospital, l4848-1 Egamicho, Sasebo 859-3244, Japan
Background: The expiration-to-inspiration sound power ratio in a midfrequency range (E/I MF), a parameter of lung sound analysis (LSA), has been reported to be useful as an index of airway inflammation in patients with bronchial asthma. However, the E/I MF reflects airway narrowing caused by airway inflammation, and there is thus concern that it may not be an index of airway eosinophilic inflammation itself.
Methods: A total of 131 patients with bronchial asthma were classified into four groups according to the presence or absence of airway narrowing and airway inflammation to examine whether the E/I MF could serve as an index of airway inflammation.
Results: The E/I MF was significantly higher in patients with a normal forced expiratory volume in one second (FEV1) and high fractional exhaled nitric oxide (FeNO), those with a low FEV1 and normal FeNO, and those with a low FEV1 and high FeNO than in those with a normal FEV1 and normal FeNO (p < 0.05–0.01). In particular, the E/I MF was high even in the patients who had no airway narrowing but had airway inflammation (p < 0.01). The results of multivariate analysis of factors involved in FeNO in patients with a normal FEV1 revealed that the E/I MF was an independent factor (p = 0.0281).
Conclusion: The E/I MF is a useful index of airway inflammation in the treatment of asthma, regardless of the presence or absence of airway narrowing.
Keywords: airway inflammation, bronchial asthma, E/I MF, FeNO, lung sound analysis
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