title: Impulse oscillometry for leukotriene D4 inhalation challenge in asthma.
abstract: BACKGROUND
  The value of impulse oscillometry (IOS) for bronchial provocation testing is poorly defined. We investigated the positive threshold derived from the parameters and diagnostic power of IOS for asthma with the leukotriene D(4) bronchial provocation test.
  
  
  METHODS
  We enrolled 62 subjects with asthma and 21 healthy subjects. IOS was employed to perform the leukotriene D(4) bronchial provocation test, followed by spirometry. The positive threshold was determined based on the cutoff point in the receiver operating characteristic curve, from which the parameters with the highest diagnostic power were obtained.
  
  
  RESULTS
  Airway impedance at 5 Hz (Z(5)), resistance at 5 Hz (R(5)), and resonance frequency had the highest diagnostic power (areas under curve 0.82, 0.82, and 0.81, respectively), with increases of 57%, 43%, and 63%, corresponding to a 20% decrease in FEV(1), respectively. IOS indices yielded assay sensitivity and specificity similar to that of spirometry. The positive threshold for IOS, defined as either a 57% increase in Z(5) or a 63% increase in resonance frequency in the bronchial provocation test, yielded an assay accuracy of 0.6 in subjects with asthma.
  
  
  CONCLUSIONS
  IOS during the leukotriene D(4) bronchial provocation test has a diagnostic power similar to that of spirometry. Either a 57% increase in Z(5) or a 63% increase in resonance frequency may be regarded as a surrogate of FEV(1) decrease to determine airway hyper-responsiveness in asthma.
authors.affiliation: State Key Laboratory of Respiratory Disease, China Clinical Research Center for Respiratory Disease, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
authors.forename: Wei Jie
authors.initials: WJ
authors.lastname: Guan
authors.forename: Jin Ping
authors.initials: JP
authors.lastname: Zheng
authors.forename: Yi
authors.initials: Y
authors.lastname: Gao
authors.forename: Cai Yu
authors.initials: CY
authors.lastname: Jiang
authors.forename: Xu
authors.initials: X
authors.lastname: Shi
authors.forename: Yan Qing
authors.initials: YQ
authors.lastname: Xie
authors.forename: Qing Xia
authors.initials: QX
authors.lastname: Liu
authors.forename: Mei
authors.initials: M
authors.lastname: Jiang
authors.forename: Jia Ying
authors.initials: JY
authors.lastname: An
authors.forename: Xin Xin
authors.initials: XX
authors.lastname: Yu
authors.forename: Wen Ting
authors.initials: WT
authors.lastname: Liu
authors.forename: Li Ping
authors.initials: LP
authors.lastname: Zhong
authors.forename: Zhong Ping
authors.initials: ZP
authors.lastname: Wu
authors.forename: Nan Shan
authors.initials: NS
authors.lastname: Zhong
mesh_terms: D000328:Adult; D000403:Airway Resistance; D019540:Area Under Curve; D001249:Asthma / Q000175:diagnosis / Q000503:physiopathology; D001985:Bronchial Provocation Tests / Q000295:instrumentation / Q000379:methods; D016085:Bronchoconstrictor Agents; D057186:Comparative Effectiveness Research; D017097:Electric Impedance; D005260:Female; D006801:Humans; D017998:Leukotriene D4; D008297:Male; D008875:Middle Aged; D009991:Oscillometry / Q000379:methods*; D011237:Predictive Value of Tests; D012372:ROC Curve; D013147:Spirometry / Q000379:methods
chemical_list: D016085:Bronchoconstrictor Agents; D017998:Leukotriene D4
keywords: airway resistance; asthma; bronchial provocation test; impulse oscillometry; leukotriene D4; resonance frequency