Rationale: Breath actuated technology (BA) allows for medication delivery to occur only on the inhalation phase of each breathing cycle, whereas breath enhanced technology (BE) delivers aerosol even during exhalation. We sought to compare the output of two high efficiency nebulizers at different inspiratory:expiratory (I:E) ratios simulating a patient breathing pattern with obstructive lung disease.

Methods: Each nebulizer/compressor (AeroEclipse* XL BAN* (BA)/Ombra* Table Top, PARI LC Sprint (BE)/PARI BOY Classic) was filled with 2mL of 1mg/mL salbutamol sulphate and the mouthpiece connected to a breathing simulator (ASL 5000). Tidal volume was fixed at 500mL, but I:E ratio and rate/minute (BPM) were varied (Table). Aerosol was collected at minute intervals and drug recovered from the filter assayed by HPLC. That mass was multiplied by fine droplet fraction (%<4.7µm) measured via Spraytec laser diffractometer to calculate fine droplet mass (FDM).

Results: Measures of FDM ((?g); mean ± SD) are summarized in the Table. FDM from the BA nebulizer was unaffected by changes in breathing pattern, whereas output from the BE nebulizer was lower and decreased with increasing I:E ratio

Conclusions: More consistent dose delivery was achieved with the BA technology rather than BE. Delivering medication only when the patient inhales would result in more stable therapy if I:E ratio was to change with disease progression or if patient took breaks to talk during treatment.