title: Analysis of Forced Expiratory Flow Signals Using the New Luus-Jaakola Optimization Procedure.
abstract: OBJECTIVE
  The aim of this study was to estimate forced vital capacity (FVC) by analyzing incomplete forced expiratory flow-time (FEFT) curves using the new Luus-Jaakola (NLJ) optimization procedure.
  
  
  METHODS
  Complete FEFT curves from 90 subjects with and without respiratory disease were used to validate the method, and its application performance was evaluated by FEFT curves containing incomplete curves from nine obstructive patients. First, a lumped parameter model of the FEFT curve, taking FVC as one of the model parameters, is chosen. The 0- 1 s, 0-1.5 s, . . . , 0-6 s curves chosen from the accepted FEFT curves are, respectively, taken as the local system observations. Then, the NLJ optimization procedure was used to get the estimate of FVC (FVCest) by estimating the model parameters. Finally, FVCest was compared with the measured FVC (FVCmea).
  
  
  RESULTS
  The difference between FVCest and FVCmea decreased with the lengths of observed curves increasing. When the lengths of observed curves reached 3 s, the mean difference (±SD) between FVCest and FVCmea was -11 ± 58 mL. Estimated FVC derived from the incomplete curves were close to FVC from accepted maneuvers.
  
  
  CONCLUSIONS
  The method can be used to estimate FVC by analyzing an incomplete FEFT curve, providing the length of the curve is more than 3 s.
  
  
  CONCLUSIONS
  This method can help the subjects who cannot complete the forced expiratory maneuver to provide a reliable estimate of FVC and also can be used to analyze the unacceptable spirometry because of early termination of exhalation.
authors: Zijun
authors: Z
authors: He
authors: Zuchang
authors: Z
authors: Ma
authors: Yubing
authors: Y
authors: Xu
authors: Yongliang
authors: Y
authors: Zhang
authors: Fusong
authors: F
authors: Hu
authors: Yining
authors: Y
authors: Sun
authors: Duoq
authors: D
authors: Zhou
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005540:Forced Expiratory Flow Rates / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D012815:Signal Processing, Computer-Assisted; D013147:Spirometry / Q000379:methods*; D014797:Vital Capacity