Abstract

The medical community has lately shown increased interest in drug administration via the internal surfaces of the lung. Administration of medication to the lungs is typically performed using either an aerosol or a spray, that is inhaled by the patient. Spray droplet size distribution is a primary determinant of whether medication will deposit effectively within the lungs. Spray liquid flow rates will determine required treatment time. Examination of three typical atomizer (nebulizer) designs used to generate inhalation sprays is presented. The separate stages in the design of these nebulizers include entrainment (jet pump), atomization, and conveyance stages. Mass flow rate of liquid in the sprays delivered from all examined designs was at least two orders of magnitude less than the mass flow rates of liquid pumped through the atomization stages. This indicated that liquid typically circulated through the atomization stages many times before being completely administered. Visualization was performed on the atomization stages showing less than ideal mechanisms for break up. Final outlet droplet cumulative number distributions obtained via Phase Doppler Particle Analyzer (PDPA) demonstrate that approximately 80% of the droplets generated by each design are within the range of sizes generally considered desirable for inhaled administration. (1–5 μm).

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