Performance of the Micro Device with Different Inspiratory Flow Rates

J. Parker, L.E.A. Hardaker, R.H.M. Hatley

The Micro mesh aerosolization device guides the patient to perform an optimum breathing maneuver through visual signals that inform the patient if their inspiratory flow rate is too fast (>14 L/min) or too slow (<7 L/min). We tested the impact of different simulated inspiratory flow rates on the quality of aerosol produced by a Micro device. One Micro device was tested in triplicate with flow rates of 8, 10, or 12 L/min, when filled with 300 μL of 5 mg/2.5 mL salbutamol sulphate solution. The inspiratory flow rate was simulated through changes to the extraction flow of a Malvern Spraytec laser diffraction system, and a 9 L/min shroud air was set up to prevent recirculation of the aerosol in the Malvern Spraytec. Record capture was started and the Micro device was connected to the Malvern Spraytec via a custom connector. Aerosolization was run into the Malvern Spraytec to completion and the aerosol generation time was recorded. The results showed that there was no change in the mean volume median diameter and very little change in the fine particle fraction (% of particles <5 μm) between the different inspiratory flow rates. In addition, the aerosolization time was equally fast with all 3 inspiratory flow rates, with a mean time of 26 seconds. There was a slight change in the span of the aerosol particle size distribution, which decreased with increasing flow. In conclusion, the particle size of the aerosol from the Micro device was consistent across a range of flow rates representative of the intended normal operating range of the device.

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