Variability of aerosol delivery via spacer devices in young asthmatic children in daily life

Pressurized metered dose inhalers (pMDI) are widely used together with spacers for the treatment of asthma in children, However, the variability of daily medication dose for pMDI/spacer combinations is not known. Electrostatic charge is a potential source of dose variability. Metal spacers have no static charge, This study assessed and compared within-subject variability of aerosol delivery of metal and plastic spacers, This was a randomized, crossover study in children with stable asthma aged 1-4 (group I, n=17) and 5-8 (group II, n=16) yrs, In both groups the amount of drug delivered to the mouth by a metal spacer (Nebuchamber(R)) and one of two plastic (polycarbonate) spacers, i.e. Babyhaler(R) in group I and Volumatici(R) in group II was measured, The metal and plastic spacers mere tested at home in a randomized order for 7 days each, using budesonide (200 mu g b.i.d.). Aerosol was collected on a filter positioned between spacer and facemask or mouth. Budesonide on the filter was assessed by high performance liquid chromatography. The mean filter dose for each child (mean+/-SD) during the 7 days was expressed as a percentage of the nominal dose. Within-subject variability was expressed as coefficient of variation (CV).Mean filter dose in group I was 41.7+/-10.1% for Nebuchamber and 26.0+/-4.0% for Babyhaler (p