title: Exhalation immediately before inhalation optimizes dry powder inhaler use.
abstract: OBJECTIVE
  Although exhalation immediately prior to inhalation (EPI) from dry powder inhalers (DPIs) is universally advised, its benefit has not been investigated. The objective of this study to assess the effects of EPI on inhaled flow from a DPI.
  
  
  METHODS
  We measured peak inhaled flow rate (PIFR) and inhaled gas volume of 25 volunteers unfamiliar with DPIs. They inhaled strongly and deeply through a flow meter either with or without EPI before and after connecting Turbuhaler or Diskus.
  
  
  RESULTS
  Median PIFR increased significantly with EPI both without connection to DPIs (178.8 versus 140.4 L min(-1)), and with connection to Diskus (75.6 versus 67.8 L min(-1)), or to Turbuhaler (51.0 versus 48.0 L min(-1)). As a result, the number of subjects whose PIFR exceeded 60 L min(-1) was significantly increased with connection to either Diskus (76 versus 64%) or to Turbuhaler (24 versus 4%). EPI significantly increased median inhaled volume both without connection to DPIs (2.84 versus 1.84 L), and with connection to Diskus (1.95 versus 1.66 L), or to Turbuhaler (1.86 versus 1.28 L). EPI significantly increased F0.2 (flow at 0.2 s after onset of inhalation) and AC30 (flow acceleration at 30 L min(-1)), parameters representing the rate of flow increase during the early phase of inhalation, in all the three groups.
  
  
  CONCLUSIONS
  EPI increases PIFR which may augment drug dispersion and facilitate fine particle generation from a DPI.
authors.affiliation: a Department of Respiratory Medicine , Shonan Fujisawa Tokushukai Hospital , Fujisawa , Kanagawa , Japan .
authors.forename: Tetsuri
authors.initials: T
authors.lastname: Kondo
authors.affiliation: a Department of Respiratory Medicine , Shonan Fujisawa Tokushukai Hospital , Fujisawa , Kanagawa , Japan .
authors.forename: Makoto
authors.initials: M
authors.lastname: Hibino
authors.affiliation: b Division of Respiratory Medicine , Atsugi Circulation Clinic , Atsugi , Kanagawa , Japan , and.
authors.forename: Toshimori
authors.initials: T
authors.lastname: Tanigaki
authors.affiliation: a Department of Respiratory Medicine , Shonan Fujisawa Tokushukai Hospital , Fujisawa , Kanagawa , Japan .
authors.forename: Motoki
authors.initials: M
authors.lastname: Ohe
authors.affiliation: c Department of Respiratory Medicine , Tokai University Oiso Hospital , Kanagawa , Japan.
authors.forename: Sakurako
authors.initials: S
authors.lastname: Kato
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D001249:Asthma / Q000188:drug therapy*; D001993:Bronchodilator Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D058995:Dry Powder Inhalers; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012129:Respiratory Function Tests
chemical_list: D001993:Bronchodilator Agents
keywords: Chronic obstructive pulmonary disease; drug delivery; handling; inhalation therapy; peak inspiratory flow