title: [Dynamic characteristics of flow trainer for dpi and its clinical relevance].
abstract: BACKGROUND
  Trainer devices are widely employed for flow instruction in the use of dry powder inhalers (DPI). However, their aerodynamic characteristics in actual use have yet to be investigated.
  
  
  METHODS
  We recorded inhalation flow signals and sounds produced from trainers for Diskus®, Symbicort®, Pulmicort® and Twisthaler® while five volunteers inhaled from the trainers with various inhalation patterns.
  
  
  RESULTS
  Inhalation flow was classified into four patterns; the best, trapezoid, delayed peak and others. All the trainers exhibited flow-thresholds with appropriate precision for instruction. Sound intensity from the Diskus® trainer was almost proportional to inhaled flow rate, and it may be useful for flow pattern estimation. In other trainers, when flow exceeded some thresholds, sounds abruptly developed and continued with high intensity. Thus, they may be convenient for recognizing appropriate flow rates. In all trainers, when the subjects inhaled rapidly and forcefully, sound developed at 0.19-0.24 s after the onset of inhalation. Thus, with this flow pattern, trainers may indicate a flow rate approaching the peak of drug dispersion from the DPI. When the subject inhaled less rapidly, the threshold for sound development decreased by 10%.
  
  
  CONCLUSIONS
  The instructor in DPI use should be aware of the aerodynamic characteristics of each individual trainer. Rapid inhalation should also be encouraged.
authors.affiliation: Department of Respiratory Medicine, Shonan Fujisawa Tokushukai Hospital.
authors.forename: Tetsuri
authors.initials: T
authors.lastname: Kondo
authors.affiliation: Department of Gastrointestinal Medicine, New Tokyo Hospital.
authors.forename: Takanori
authors.initials: T
authors.lastname: Shimizu
authors.affiliation: Division of Respiratory Medicine, Atsugi Circulation Clinic.
authors.forename: Toshimori
authors.initials: T
authors.lastname: Tanigaki
authors.affiliation: Department of Respiratory Medicine, Shonan Fujisawa Tokushukai Hospital.
authors.forename: Makoto
authors.initials: M
authors.lastname: Hibino
authors.affiliation: Department of Respiratory Medicine, Shonan Fujisawa Tokushukai Hospital.
authors.forename: Motoki
authors.initials: M
authors.lastname: Ohe
authors.affiliation: Department of Respiratory Medicine, Tokai University Oiso Hospital.
authors.forename: Sakurako
authors.initials: S
authors.lastname: Tajiri
mesh_terms: D000280:Administration, Inhalation; D001249:Asthma / Q000188:drug therapy; D058995:Dry Powder Inhalers / Q000295:instrumentation*; D006801:Humans; D013997:Time Factors