title: Predictive equations and the reliability of the impulse oscillatory system in Japanese adult subjects.
abstract: BACKGROUND
  The impulse oscillation system (IOS) measures respiratory impedance (Zrs) in terms of resistance (Rrs) and reactance (Xrs) at multiples of 5 Hz. These measurements can be used clinically to help diagnose and monitor respiratory disorders, independent of effort.
  
  
  METHODS
  The predictive equation for resistance at 5 and 20 Hz and impedance at 5 Hz (R5, R20, X5), for the first time, in 299 Japanese adult subjects was determined. In addition, the within single day variation and between day variation were determined.
  
  
  RESULTS
  The predictive equation for R5, R20 and X5 revealed a clear difference with respect to the subject's smoking history (lifelong non-smoker, n = 166, adjusted r = 0.55, 0.46 and 0.57, respectively, vs. smoker, n = 133, adjusted r = 0.47, 0.42 and 0.47, respectively). This difference was less obvious with respect to gender (female, n = 120, adjusted r = 0.42, 0.20 and 0.47, respectively, vs. male, n = 179, adjusted r = 0.46, 0.37 and 0.47, respectively). The predictive equations were dependent on the log of height (H) for both R5 and R20, and on age and log of height for X5. The equations were: R5 (KPa/L/s) = -3.841167 x logH + 8.671580; R20 (KPa/L/s) = -2.546561 x logH + 5.841867; and X5 (KPa/L/s) = -0.000097 x Age + 1.018597 x logH - 2.343672. For these parameters there were no statistically significant differences for within day repeatability or between day variations (P > 0.05), suggesting a high degree of reproducibility for IOS measurements.
  
  
  CONCLUSIONS
  It was possible to determine a predictive equation and confirm a high degree of reliability of IOS parameters in Japanese adult subjects.
authors.affiliation: Department of Respiratory Medicine, Juntendo University, School of Medicine, Hongo, Tokyo, Japan. s-shiota@iea.att.ne.jp
authors.forename: Satomi
authors.initials: S
authors.lastname: Shiota
authors.forename: Masako
authors.initials: M
authors.lastname: Katoh
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Fujii
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Aoki
authors.forename: Rokuro
authors.initials: R
authors.lastname: Matsuoka
authors.forename: Yoshinosuke
authors.initials: Y
authors.lastname: Fukuchi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000403:Airway Resistance / Q000502:physiology*; D044466:Asian People; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D007320:Inspiratory Capacity / Q000502:physiology; D007564:Japan; D008297:Male; D008875:Middle Aged; D009991:Oscillometry; D011237:Predictive Value of Tests; D012044:Regression Analysis; D015203:Reproducibility of Results; D012120:Respiration Disorders / Q000175:diagnosis; D012129:Respiratory Function Tests / Q000379:methods*; D015656:Respiratory Mechanics / Q000502:physiology*