Introduction and objectives Laboratory evaluation of VHC-facemask add-ons is ideally undertaken simulating conditions of use. We report a study in which VHC-facemask add-on devices for infants and small children use were evaluated using anatomical models.

Methods 2 VHCs with facemask (n=3 devices/group) were evaluated using anatomical models comprised of airway replicas commensurate with that of a 7 month old infant and 4 year old child. Each VHC was prepared to manufacturer instructions, then evaluated by breathing simulator (ASL5000), mimicking a short coordination delay of 2 s followed by age appropriate tidal breathing. The facemask was attached to ADAM-III infant and child anatomical models. The airways were coupled directly to the breathing simulator via a filter below its exit to capture drug particles that would penetrate as far as the carina in a real patient. 5-actuations of fluticasone propionate (50 µg, FP) were delivered at 30 s intervals. FP recovered from various locations in the aerosol pathway was subsequently assayed by HPLC-UV spectrophotometry.

Results The distribution of recovered FP from each type of VHC is summarized in table 1.

Conclusions Significantly more FP was delivered to the model ‘carina’ from the AC Plus VHC (p<0.001), the increased mass counterbalanced by decreased retention of medication within the VHC. It is important that clinicians are aware that large differences in delivery efficiency may exist when a facemask is present and some VHCs may fail to deliver any medication in certain cases.