Solving AeroChamber alert whistle inconsistencies
Mark Sanders1, Aurelien Martin1 & Darragh Murnane1
1University of Hertfordshire, College Lane, Hatfield, AL10 9AB, UK
Summary
The incidence of inhaler errors, some of which are critical, is high. Spacers are used as a means of reducing throat deposition and mitigating inhaler error. Some spacers such as Aerochamber Plus include an alert whistle to indicate a subject inhaling too fast. In the current study the flow rate at which the Aerochamber Plus whistle was activated was found to vary for different pMDIs, creating the potential to confuse. The range of whistle response was from 30 LMin-1 (Atrovent) to 140 LMin-1 (Flutiform), and is related to device resistance, higher resistance pMDIs sounded at a lower flow rate than low resistance pMDIs. This problem was attributed to the location of the whistle in the chamber where air enters through the pMDI and the whistle, the balance of which is determined by device resistance. The problem can be solved by moving the whistle to the mouthpiece area which then produces consistent whistle activation across all pMDIs.