Determination of ability of a one-way valve to prevent bacterial transfer from patient to inhaler
Mark Sanders1, Ron Bruin1, Richard Webb2 & Gillian Iredale2
1Clement Clarke International Limited, Edinburgh Way, Harlow,
Essex, CM20 2TT, UK
2Industrial Microbiological Services Limited, Pale Lane, Hartley Wintney, Hampshire, RG27 8DH, United Kingdom
Background Placebo demonstrator inhalers are an important but limited technique training resource owing to the single patient use recommendation—absent decontamination—to avoid microbial contamination. This randomised study has looked in vitro at the potential for preventing a contamination that could arise if the inhaler was shared between users but used with single-use mouthpieces.
Methods A bespoke version of the Flo-Toneâ inhaler technique training aid (FTR) has been developed for use with Respimatâ soft-mist inhaler trainer, and further engineered to include a one-way valve (FTRv) to isolate the inhaler if the patient exhales into the device. Disinfected, aseptically air-dried FTR and FTRv, and associated Respimat inhalers (n = 10 replicates) were compared using a 10 s stimulated contaminated expiration delivered via a customised rig comprising air syringe, holding chamber, modified nebuliser, and high dose (7.8 x 108 CFU.mL-1) Pseudomonas aeruginosa inoculum (strain NCIMB 10421). Surviving bacteria from each inhaler were enumerated by quantitative re-suspension and dilution with a detection limit of 15 colony forming units (CFU) per inhaler. The statistical significance of the differences was determined by Student’s t-test following log10 transformation.
Results Geometric mean CFU per Respimat inhaler was 5.6 x 104 for FTR and 2.8 x 102 for FTRv (p < 0.0001): a reduction of > 98 %.
Conclusions Equating this performance to the clinical risk, the valved mouthpiece has shown performance capable of reducing microbial exposure to an extremely small level, and below that which a patient is likely to inhale from environmental air in the course of their normal dosing inhalation, and to an extent that could permit low-risk sharing of scarce placebo resources.