Characteristics of aerosol plumes from various inhalers for COPD maintenance therapy: SMI, DPI and pMDI

Clinical Research Results Abstract Introduction:Inhaled medications are required for patients with COPD. Various inhaler types are available: dry powder inhalers (DPIs), soft mist inhalers (SMIs) and pressurised metered-dose inhaler (pMDIs). For active inhalers, aerosol generation relies on the inhaler (pMDI, SMI), whereas for DPIs a patients’ inspiratory flow is important. The objective of this work was to assess the aerosol characteristics velocity and duration, as these impact the dose to the lungs.Methods:The experimental set-up included a lung simulator, video recorder and COPD maintenance inhalers, each enclosed in airtight casing with an air inlet and opening for the mouthpiece. Air was delivered by the programmable lung simulator to generate plumes. Active devices were also released in quiescent air. Exit/plume velocity and duration were assessed for each inhaler.Results:SMIs are unique with respect to their long spray duration and fast decrease in exit velocity. pMDIs have a higher exit velocity aerosol plume, which is not strongly influenced by the airflow rate passing through the device. In contrast, aerosols generated by DPIs depend on airflow and their design (outlet diameter), with different aerosol velocities and formations observed.DiscussionThe effectiveness of inhaled therapies depends upon the dose delivered to the lungs, which is in turn affected by inhaler/aerosol characteristics. This in vitro study demonstrates the differences between inhaler types in terms of their aerosol plume characteristics. Oropharyngeal deposition is associated with aerosol velocity (higher -> more deposition); for active inhalers, co-ordination between inhalation and generating the aerosol is also critical for lung deposition, with a longer spray duration reducing the criticality of precise co-ordination. For DPIs, the different aerosol generation mechanisms (e.g., blister, capsule, reservoir) result in a variety of plumes and durations, with the exit velocity (affecting oropharyngeal deposition) depending on the inner mouthpiece diameter and the airflow rate applied. Research Idea Abstract Service Development & Evaluation Abstract Declaration of Interest The analysis was funded by Boehringer Ingelheim. Herbert Wachtel and Rachel Emerson-Stadler are employees of Boehringer Ingelheim. Peter Langguth has nothing to declare. References and Clinical Trial Registry Information