title: Prediction of airway inflammation in patients with asymptomatic asthma by using lung sound analysis.
abstract: BACKGROUND
  The intensity and frequency of sounds in a lung sound analysis (LSA) may be related to airway constriction; however, whether any factors of an LSA can predict airway eosinophilic inflammation in patients with asthma is unknown.
  
  
  OBJECTIVE
  To determine whether an LSA can predict airway eosinophilic inflammation in patients with asymptomatic asthma.
  
  
  METHODS
  The expiratory-inspiratory ratios of sound power in the low-frequency range (E-I LF) from 36 patients with asymptomatic asthma were compared with those of 14 healthy controls. The relations of E-I LF with airway eosinophilic inflammation were analyzed. The E-I LF cutoff value for predicting airway eosinophilic inflammation also was analyzed.
  
  
  RESULTS
  The mean ± SD E-I LF was higher in the patients with asthma and with increased sputum eosinophils than in those patients without increased sputum eosinophils (0.45 ± 0.24 vs 0.20 ± 0.12; P < .001) or in the healthy controls (0.25 ± 0.10; P = .003). A multiple regression analysis showed that the sputum eosinophil ratio and exhaled nitric oxide were independently correlated with E-I LF, P = .0003 and P = .032, respectively. For the prediction of increased sputum eosinophils and increased fractional exhaled nitric oxide levels, the E-I LF thresholds of 0.29 and 0.30 showed sensitivities of 0.80 and 0.74 and specificities of 0.83 and 0.77, respectively.
  
  
  CONCLUSIONS
  We showed that LSAs can safely predict airway inflammation of patients with asymptomatic asthma.
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: Kyoto Respiratory Center, Otowa Hospital, Kyoto, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Nagasaka
authors.affiliation: Department of Respiratory Medicine, Kawasaki Medical School, Kurashiki, Okayama, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Obase
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: D000162:Acoustics; D000328:Adult; D001249:Asthma / Q000175:diagnosis* / Q000276:immunology / Q000503:physiopathology; D058070:Asymptomatic Diseases; D001944:Breath Tests; D001985:Bronchial Provocation Tests; D016022:Case-Control Studies; D004804:Eosinophils / Q000276:immunology; D045853:Exhalation; D005260:Female; D005541:Forced Expiratory Volume; D005583:Fourier Analysis; D006801:Humans; D001239:Inhalation; D007958:Leukocyte Count; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism; D011237:Predictive Value of Tests; D011657:Pulmonary Eosinophilia / Q000175:diagnosis* / Q000276:immunology / Q000503:physiopathology; D012135:Respiratory Sounds; D013018:Sound Spectrography; D013183:Sputum / Q000166:cytology / Q000276:immunology; D055815:Young Adult
chemical_list: D009569:Nitric Oxide
keywords: Airway inflammation; Bronchial asthma; Lung sound analysis