The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts

EVALUATION OF TWO VALVED HOLDING CHAMBERS WITH FACEMASK USING A NEW INFANT FACE MODEL: IMPORTANCE OF AVOIDING LEAKAGE BETWEEN FACEMASK AND FACE

Dominic P. Coppolo1, Jolyon P. Mitchell2, Heather A. Mackay2, Valentina I. Avvakoumova2, Mark W. Nagel2



Background: Valved Holding Chambers (VHCs) with facemask as patient interface are an important adjunct in delivery of medication particularly to infants. Leakage between facemask and face can result in severe loss of medication because there is no pressure source to drive the aerosol towards the patient once the inhaler has been actuated. Laboratory performance testing therefore needs to be undertaken with the facemask in place.

Methods: We evaluated the effect of two different but similar-sized VHCs (AeroChamber Plus® with small mask - Monaghan Medical Corp.) and Vortex® with Babywhirl™ mask - PARI Respiratory Equipment Inc., Midlothian, PA) on delivery of albuterol (2-actuations of Ventolin® HFA, GlaxoSmithKline) to an oral-breathing 9-12 month anatomical infant face model with simulated in-vivo facial surfaces where the mask was applied with a clinically relevant force of 1.6 kg. The VHCs were prepared in accordance with manufacturer instructions and evaluated at a flow rate of 4.9 L/min, sampling the aerosol by low-flow impactor to determine total emitted mass (TEM) and fine particle fraction (FPF) < 4.7 μm aerodynamic diameter. These conditions were considered to be representative of a 6-12 month old infant having a 50th percentile body weight range from 7.5 to 9.9 kg. Recovered albuterol was determined by HPLC-UV spectrophotometry.

Results: TEM/kg (n = 5 devices, mean ± SD) from the AeroChamber Plus® VHCs was in the range 1.6 to 2.2 μg/kg, comparable with data provided in the Patient Information Leaflet for this formulation with infant users, and FPF was 73%. No leakage was detected between facemask and face (100% flow to the face via the VHC). In contrast, a perfect seal could not be achieved between the Vortex® VHCs and associated wider facemask with the model face (97% of the flow by-passed the VHC under best conditions achievable), so that TEM/kg from these devices ranged from 0.07 to 0.09 μg/kg, with FPF of 100%.

Conclusion: The Aerosol-Delivery-to-Anatomical-Model (ADAM-II) face technique allows laboratory testing of VHC-facemask to be evaluated as a complete system. The data obtained confirm that no leakage between facemask and face must be achieved for reliable delivery of medication from these devices.