title: [Study on respiratory impedance of patients with extratracheal tumour].
abstract: OBJECTIVE
  To determine the manifestation of impulse oscillometry (IOS) in variation of respiration impedance on patients with extratracheal tumour.
  
  
  METHODS
  The IOS indices in 30 normal persons and 28 patients with extracheal tumour were measured. The ratio of forced expiratory volume after 1 second to forced vital capacity (FEV1/FVC) was evaluated and the maximal expiratory flow-volume curve (MEFV curve) was examined. The above values with t-test of SPSS statistics software were analyzed.
  
  
  RESULTS
  Compared with the normal group, in the extratracheal group the ratio of actual value of resistance to the predict from 20 Hz to 35 Hz increased obviously and this only occurred with the reactance at 20 Hz (P < 0.01). The resistance curve showed clear rise after the 20 Hz and the reactance curve peaked at 20 Hz and was leveled to normal at 35 Hz.
  
  
  CONCLUSIONS
  IOS is capable of presenting the distinctive indices for the study of respiration impedance on patients with extratracheal tumour.
authors.affiliation: Pulmonary Function Laboratory, Chest Hospital, Tianjin 300051, China.
authors.forename: C
authors.initials: C
authors.lastname: Li
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.forename: L
authors.initials: L
authors.lastname: Zhao
mesh_terms: D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009991:Oscillometry; D012129:Respiratory Function Tests; D012137:Respiratory System / Q000503:physiopathology*; D014134:Tracheal Neoplasms / Q000503:physiopathology*