AN IN-VITRO METHOD FOR DETERMINING REGIONAL DOSAGES DELIVERED BY JET NEBULIZERS

A methodology for determining the regional dosages delivered to the re spiratory tract by a jet nebulizer is presented and applied to the DeV ilbiss PulmoNeb (R) disposable nebulizer delivering a 2.5 ml nebule of Ventolin (R) (1 mg/ml salbutamol sulphate). Results are obtained both with tapping of the nebulizer, which enhances nebulizer performance, and without tapping. The nebulizer output is characterised by measurin g the total mass and the mass of solids leaving the nebulizer per minu te, and performing a control volume analysis of the nebulizer. Particl e size distributions are determined by phased Doppler anemometry. Depo sition probabilities are calculated using a semi-empirical model for t he deposition of hygroscopic aerosol particles in healthy adult Caucas ian males. Deposition probabilities are then converted to regional dos ages using the measured nebulizer output characteristics. The regional dosages (% of initial dose in nebulizer) of Ventolin(R) delivered to the extrathoracic, bronchial, and alveolar regions of the respiratory tract are 0.248+/-0.005 mg (9.9%), 0.034+/-0.001 mg (1.4%), and 0.071/-0.002 mg (2.8%) respectively when the nebulizer was tapped during op eration, and 0.184+/-0.005 mg (7.4%), 0.025+/-0.001 mg (1.0%), and 0.0 52+/-0.002 mg (2.1%) when tapping was not used. This methodology provi des a well controlled and rapid means of comparing the effectiveness o f different nebulizers for use in aerosol therapy.