title: Evaluation of airflow limitation using a new modality of lung sound analysis in asthmatic children.
abstract: BACKGROUND
  Reliable assessment of not only symptoms but also lung function is essential in asthma management. We developed a new technology for analyzing lung sounds and assessed its clinical usefulness in asthmatic children.
  
  
  METHODS
  Forty-four children underwent lung sound recording with simultaneous airflow measurement using a sensor on the upper right anterior chest. We calculated a sound parameter index from the amplitude of inspiratory lung sounds at 700 Hz (ic700). ic700 were compared depending on flow and body size. In addition, 184 asthmatic children and 16 non-asthmatic children underwent lung sound analysis and lung function test in an asymptomatic state. In the asthma group, 135 children received treatment continually. The untreated asthma group included 28 children who had never received treatment continually and 21 children who had not been treated for at least 1 year. The asthmatic children were divided into four classes according to asthma severity. ic700 were compared depending on spirometric parameters and asthma severity classification.
  
  
  RESULTS
  The influences of flow and body size were negligible for ic700. ic700 correlated with FEV1%, MMF and FEF50 (r = -0.436, -0.339 and -0.302, respectively). There was a significant difference of ic700 between asthmatic and non-asthmatic children (p < 0.001), and ic700 correlated with the classification of asthma severity (p < 0.001). The ic700 scores of the severe group were higher than those of the intermittent group and non-asthmatic children.
  
  
  CONCLUSIONS
  It was possible to evaluate airway dysfunction of asthma using ic700, which was calculated non-invasively by analyzing lung sounds alone, without measuring body size and airflow.
authors.affiliation: Department of Pediatrics, Minami Wakayama Medical Center, Wakayama, Japan. Electronic address: gd6c-hbkw@asahi-net.or.jp.
authors.forename: Chizu
authors.initials: C
authors.lastname: Habukawa
authors.affiliation: Department of Pediatrics, Kinki University Sakai Hospital, Osaka, Japan.
authors.forename: Katsumi
authors.initials: K
authors.lastname: Murakami
authors.affiliation: R&D Division, Panasonic Corporation, Osaka, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Endoh
authors.affiliation: R&D Division, Panasonic Corporation, Osaka, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Yamada
authors.affiliation: R&D Division, Panasonic Corporation, Osaka, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Horii
authors.affiliation: Department of Pulmonary Medical Center, Otowa Hospital, Kyoto, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Nagasaka
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000175:diagnosis* / Q000503:physiopathology*; D049628:Body Size; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D012123:Pulmonary Ventilation; D012129:Respiratory Function Tests; D012135:Respiratory Sounds; D012720:Severity of Illness Index; D013147:Spirometry
keywords: Airway obstruction; Asthma; Children; Lung sound analysis; ic700