title: Evaluation of airway responsiveness using colored three-dimensional analyses of a new forced oscillation technique in controlled asthmatic and nonasthmatic children.
abstract: BACKGROUND
  Bronchodilator response (BDR) is routinely used in asthma management. A new forced oscillation technique (FOT) is able to quickly measure respiratory system resistance (Rrs) and reactance (Xrs) at each tidal breath phase. The present study evaluated bronchial changes by using the new FOT.
  
  
  METHODS
  Respiratory resistance and reactance were measured using FOT in 132 children (age, 10.86±4.78 years; M:F=88:44), including asthmatic (n=98) and nonasthmatic children (n=34), pre- and post-bronchodilator inhalation in an asymptomatic state. Whole-breath or within-breath changes in Rrs and Xrs were measured and compared pre- and post-bronchodilator inhalation and between each group. All patients performed spirometry and forced expiratory nitric oxide pre- and post-bronchodilator inhalation.
  
  
  RESULTS
  Spirometric parameters showed significant positive changes at V50 and V25 in both groups; however, these changes were not significantly different between the groups. eNO was significantly higher in the asthmatic group than in the nonasthmatic group; however, there was no significant change pre- and post-inhalation in either group. Rrs in the asthma group was significantly higher in the expiratory phase than in the inspiratory phase. Rrs and Xrs before and after bronchodilator inhalation were significantly different in the asthma group alone, except for the expiratory-inspiratory phase of each of these parameters. Changes in Rrs and Xrs at 5Hz (R5 and X5) in a whole-breath and the inspiratory phase were significantly different between the groups.
  
  
  CONCLUSIONS
  Changes in X5 and R5 reflect bronchial reversibility. The new FOT is useful for asthmatic children.
authors.affiliation: Department of Pediatrics, Kinki University Sakai Hospital, 2-7-1 Harayamadai, Minami-ku, Sakai, Osaka 590-0132, Japan. Electronic address: k-murakami@sakai.med.kindai.ac.jp.
authors.forename: Katsumi
authors.initials: K
authors.lastname: Murakami
authors.affiliation: Department of Pediatrics, Minami Wakayama Medical Center, 27-1 Takinai-machi, Tanabe-shi, Wakayama 646-0015, Japan. Electronic address: gd6c-hbkw@asahi-net.or.jp.
authors.forename: Chizu
authors.initials: C
authors.lastname: Habukawa
authors.affiliation: Environment and Safty Center, Tohoku University, 1-1 Seiryou-cho, Aoba-ku, Sendai-shi, Miyagi 980-8574, Japan. Electronic address: kurosawa-thk@m.tohoku.ac.jp.
authors.forename: Hajime
authors.initials: H
authors.lastname: Kurosawa
authors.affiliation: Department of Pediatrics, Kinki University, 277-1 Ohonohigashi, Osakasayama-shi, Osaka 589-8511, Japan. Electronic address: tsukasa@med.kindai.ac.jp.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Takemura
mesh_terms: D000280:Administration, Inhalation; D000293:Adolescent; D000403:Airway Resistance / Q000502:physiology*; D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D001985:Bronchial Provocation Tests / Q000379:methods*; D016084:Bronchoconstriction / Q000502:physiology*; D001993:Bronchodilator Agents / Q000008:administration & dosage; D002648:Child; D002675:Child, Preschool; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D009991:Oscillometry / Q000379:methods*; D013147:Spirometry
chemical_list: D001993:Bronchodilator Agents
keywords: Asthma; BDR; Bronchial reversibility; Children; FEV(1); FOT; Forced oscillation technique; Fres; Rrs; Xrs; bronchodilator response; eNO; forced expiratory nitric oxide; forced expiratory volume in 1 s; forced oscillation technique; reactance; resonant frequency; respiratory system resistance