Design and assessment of an adherence monitoring device for inhalers

Methods We designed a device with a high fidelity microphone and small sized acoustic storage to make time stamped acoustic recordings of an individual’s use of an inhaler. We related the acoustic features to the various steps involved in the correct use of an inhaler. We established a minimum acoustic profile required to use the inhaler correctly, thereby objectively quantifying technique. A cohort of subjects with moderate/severe asthma (n=44) used a salmeterol/fluticasone discus inhaler with the device attached for a month. The subjects were instructed in the use of the inhaler.