title: Lung Sound Analysis and Airway Inflammation in Bronchial Asthma.
abstract: Our previous study on lung sound analysis (LSA) revealed that the expiration-to-inspiration sound power ratio in a low-frequency range (E/I LF) was increased in patients with bronchial asthma, even when they have no wheezes.
  
  
  
  We also monitored the expiration-to-inspiration sound power ratio in a mid-frequency range (E/I MF) and the mid- to low-frequency sound power ratio for inspiration and expiration (ie, I MF/LF and E MF/LF, respectively) using a new software program to examine which parameter is most suitable as an index of airway inflammation in patients with asthma.
  
  
  
  A study was conducted in 31 patients with mild-to-moderate bronchial asthma to examine potential correlations of LSA parameters (E/I LF, E/I MF, I MF/LF, and E MF/LF) with spirogram parameters, airway hyperresponsiveness (PC20), fractional exhaled nitric oxide (NO), and sputum eosinophils.
  
  
  
  E/I LF was significantly correlated with airway narrowing (forced expiratory volume in 1 second [FEV1.0]/forced vital capacity [FVC]%: r = -0.50, maximal expiratory flow at 50% [V50],%pred: r = -0.50) and peripheral airway inflammation (alveolar NO: r = 0.36, eosinophils in peripheral sputum: r = 0.41). E/I MF was significantly correlated with airway narrowing (FEV1.0/FVC%: r = -0.46, V50,%pred: r = -0.49), airway inflammation (bronchial NO: r = 0.43, alveolar NO: r = 0.47, eosinophils in peripheral sputum: r = 0.50), and airway hyperresponsiveness (logPC20: r = -0.49). E MF/LF was significantly correlated with airway inflammation (NO: r = 0.36, eosinophils in sputum: r = 0.40) and airway hyperresponsiveness (logPC20: r = -0.40). I MF/LF was not significantly correlated with any parameters.
  
  
  
  Among the 4 LSA parameters investigated, E/I MF demonstrated the highest correlation with airway inflammation, and also with bronchial hyperresponsiveness.
authors.affiliation: Clinical Research Center, Fukuoka National Hospital, Fukuoka, Japan. Electronic address: t-shimoda@mfukuoka2.hosp.go.jp.
authors.forename: Terufumi
authors.initials: T
authors.lastname: Shimoda
authors.affiliation: Second Department of Internal Medicine, School of Medicine, Nagasaki University, Nagasaki, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Obase
authors.affiliation: Kyoto Respiratory Center, Otowa Hospital, Kyoto, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Nagasaka
authors.affiliation: Clinical Research Center, Fukuoka National Hospital, Fukuoka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakano
authors.affiliation: Clinical Research Center, Fukuoka National Hospital, Fukuoka, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Kishikawa
authors.affiliation: Clinical Research Center, Fukuoka National Hospital, Fukuoka, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Iwanaga
mesh_terms: D000328:Adult; D001249:Asthma / Q000175:diagnosis* / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology; D004804:Eosinophils / Q000276:immunology; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism; D012119:Respiration; D012135:Respiratory Sounds / Q000175:diagnosis* / Q000276:immunology / Q000503:physiopathology; D012984:Software; D013183:Sputum / Q000166:cytology; D014797:Vital Capacity
chemical_list: D009569:Nitric Oxide
keywords: Airway hyperresponsiveness; Airway inflammation; Airway obstruction; Bronchial asthma; Lung sound analysis