Introduction and Objectives Priming VHCs with several actuations of medication before use may be an established practice to prepare the spacer before use. However this practice can have a significant influence on subsequent medication delivery. The present study set out to test the hypothesis that priming is not effective, or better than the use of anti-static materials.

Methods The following VHCs, each with mouthpiece as patient interface (n=5 devices/group) were evaluated: AeroChamber Plus Flow-Vu Antistatic VHC (AC +FV AVHC); AeroChamber Plus; Volumatic^…; Able Spacer 2^…; Anti-Static Compact Space Chamber plus^…. Each VHC was connected via a filter holder to a vacuum source operated at 28.3 L/min, evaluated with a pMDI (Flovent 125 µg, FP) and the Emitted Mass of FP (EM_FP) determined by HPLC-UV assay. The following sequence of testing was conducted: 1) Test VHC immediately after removal from packaging (no pre-treatment) and evaluate EM_FP following one actuation. 2) Supply two more actuations into the same VHC and evaluate EM_FP (representing 3 actuations of priming).3) Deliver 17 more actuations into the same VHC and evaluate EM_FP (representing priming of 20 actuations). 4) Clean VHC, then repeat part (1) (representing pre-conditioning by washing as an alternative to priming).

Results The behaviour of EM_FP (mean ±SD) with VHC type is summarised in figure 1.

Conclusions Clinicians should be aware that priming of VHCs Results in inconsistent medication delivery, and is wasteful of medication.

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Abstract P279 Figure 1