Exhalation immediately before inhalation optimizes dry powder inhaler use

AbstractObjective: 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 conn...