title: [Resistances of dry powder inhalers and training whistles and their clinical significance].
abstract: BACKGROUND
  Flow resistance of dry powder inhaler (DPI) is important information when physician choose a suitable DPI to individual patient. We previously reported flow resistances of several DPIs and training devices. In the present in vitro study, we measured resistances of new DPIs and new trainers.
  
  
  METHODS
  Flow resistances were obtained from driving pressure and flow through the devices.
  
  
  RESULTS
  All devices had parabolic relationships between the driving pressure and flow. Resistances were: 8.44 ± 0.45×10-2(mean±SD) for Elipta®, 5.53±0.13×10-2 for Breezhaler®, 7.27 ± 0.40×10-2 for new Diskhaler®, 12.15 ± 0.40×10-2 for Swinghaler®, 7.07 ± 0.24×10-2 for new Diskus trainer, 8.72 ± 0.4.5×10-2(√cmH2O/L/min) for Elipta trainer. Sounding threshold of Diskus trainer was 38.1 ± 5.1 and that of Elipta trainer was 39.9 (meidan) L/min.
  
  
  CONCLUSIONS
  In change from Diskus® to Elipta®, flow instruction is not necessary. Breezhaler® is a suitable DPI for patients with low pulmonary function but patients should be alert to avoid excessively high inhalational flow. In flow instruction, a flow higher than trainer sounding should be advised.
authors: Department of Respiratory Medicine, Shonan Fujisawa Tokushukai Hospital.
authors: Tetsuri
authors: T
authors: Kondo
authors: Division of Respiratory Medicine, Atsugi Circulation Clinic.
authors: Toshimori
authors: T
authors: Tanigaki
authors: Department of Respiratory Medicine, Shonan Fujisawa Tokushukai Hospital.
authors: Makoto
authors: M
authors: Hibino
authors: Department of Respiratory Medicine, Shonan Fujisawa Tokushukai Hospital.
authors: Motoki
authors: M
authors: Ohe
authors: Department of Respiratory Medicine, Tokai University Oiso Hospital.
authors: Sakurako
authors: S
authors: Kato
mesh_terms: D058995:Dry Powder Inhalers / Q000295:instrumentation*