Delivered Dose Efficiency of Conventional Jet Nebulizers – Does It Allow Comparison of the Likely Effective Performance?

S. Byrne, D. Jeffrey & R.H.M. Hatley

Nebulizers with different modes of operation differ considerably in terms of particle size, delivered dose, and efficiency. (1) The question is how much do 2 nebulizers of the same mode of operation differ in terms of relative delivered and respirable delivered dose efficiency?

In this study, we focus on 2 conventional nebulizers: the Salter 8900 and SideStream Disposable nebulizer. Although conventional nebulizers are simple devices with few parts and are similar in appearance, this does not mean that they are equivalent. The 2 conventional nebulizers were compared in terms of particle size by laser diffraction and delivered dose using simulated breathing patterns with different inhalation:exhalation ratios. To characterize the nebulizers, 2.5 mL of 5 mg/2.5 mL salbutamol sulphate solution was used. Three of each nebulizer type were tested in triplicate, resulting in n=9. A filter was used and placed between the ASL 5000 breathing simulator and the nebulizer to capture the aerosol available to the patient. Aerosol deposited on the filter was analyzed by high performance liquid chromatography. Respirable delivered dose and respirable delivered dose efficiency were subsequently calculated from the particle size, delivered dose and nebulizer fill. All percentages are expressed relative to nebulizer fill. The delivered dose efficiency for the Salter 8900 nebulizer ranged from 14.90% to 5.58% across the breathing patterns, and for the SideStream Disposable nebulizer it ranged from 14.88% to 7.99%. Efficiency in terms of respirable delivered dose ranged from 4.49% to 1.68% for the Salter 8900 nebulizer compared with 10.63% to 5.71% for the SideStream Disposable nebulizer across the breathing patterns. The 2 nebulizer types had similar delivered dose efficiencies, but the SideStream Disposable nebulizer was the more efficient nebulizer in terms of respirable delivered dose.

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