title: Analysis of the contributing factors to airway hyperresponsiveness by a forced oscillation technique in patients with asthma.
abstract: BACKGROUND
  Forced oscillation technique (FOT) is increasingly used to obtain much information on the state of the respiratory system. However, there are little data about FOT parameters on methacholine provocation test in adult asthma. This study was designed to determine the physiological implications of FOT parameters during methacholine provocation and analyze the major contributing factors to airway hyperresponsiveness (AHR) in asthma.
  
  
  METHODS
  Spirometry and FOT were performed in 22 asthmatic patients and 21 normal control subjects before and after provocation with a maximal dose of methacholine.
  
  
  RESULTS
  In asthmatic patients, the percent increase in resistance at 5 Hz (R5) and resistance at 20 Hz (R20) after the methacholine provocation was 70 [45-93] % and 16 [5-23] %. The percent change in R20 was not significantly correlated with the percent change in FVC or FEV1. Similarly, the percent change in R5 was not significantly correlated with the percent change in FEV1, but was significantly correlated with the percent change in FVC. Moreover, the percent change in R5 was significantly correlated with the closing index (r = 0.55, p = 0.01). In addition, AHR to methacholine was closely correlated with the percent change in R5 (r = -0.71, p = 0.001).
  
  
  CONCLUSIONS
  Simultaneous measurement of FOT and bronchial challenge test provide meaningful information, and greater change in R5 may represent exaggerated response of small airways in asthmatic patients. This study will provide new insights into the physiological implications of each FOT parameter in asthmatic patients.
authors: Yumiko
authors: Y
authors: Imahashi
authors: Hiroshi
authors: H
authors: Kanazawa
authors: Naoki
authors: N
authors: Ijiri
authors: Naoko
authors: N
authors: Yoshii
authors: Gakuya
authors: G
authors: Tamagaki
authors: Kazuhisa
authors: K
authors: Asai
authors: Yoshihiro
authors: Y
authors: Tochino
authors: Kazuto
authors: K
authors: Hirata
mesh_terms: D000328:Adult; D000403:Airway Resistance; D001249:Asthma / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D016084:Bronchoconstriction; D016085:Bronchoconstrictor Agents; D016022:Case-Control Studies; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D011237:Predictive Value of Tests; D012307:Risk Factors; D013147:Spirometry / Q000379:methods*; D014797:Vital Capacity
chemical_list: D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride