Experimental Evaluation of Perfluorocarbon Aerosol Generation with Two Novel Nebulizer Prototypes

Abstract

The potential of non-invasive ventilation procedures and new minimally invasive techniques has resulted in the research of alternative approaches as the aerosolization for the treatment of respiratory distress syndrome (RDS). The aim of this work was to design two nebulizer prototypes and to evaluate them studying the particle size distribution of the inhaled droplets generated with distilled water and two perfluorocarbons (PFCs). Different experiments were performed with driving pressures of 1⁻3 bar for each compound. An Aerodynamic Particle Sizer was used to measure the aerodynamic diameter (Da), the mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD). The results showed that both prototypes produced heterodisperse aerosols with Da mean values in all cases below 5 µm. The initial experiments with distilled water showed MMAD values lower than 9 µm and up to 15 µm with prototype 1 and prototype 2, respectively. Regarding the PFCs, relatively uniform MMAD values close to 12 µm were achieved. The air delivery with outer lumens of prototype 1 presented more suitable mass distribution for the generation and delivery of a uniform aerosol than the two half-circular ring geometry proposed in the prototype 2.

Keywords: aerodynamic particle sizer; aerosol; drug delivery; nebulizer; particle size distribution.

Figure A1

Mass and number distribution of an H₂Od aerosol sample with prototype 1 (left) and prototype 2 (right). (Screenshots taken directly from the Aerosol Instrument Manager software).

Figure 1

(a) 3D visualization of the prototype, distal section of (b) prototype 1, (c) prototype 2. Distal section of the manufactured (d) prototype 1 and (e) prototype 2.

Figure 2

(a) Aerodynamic Particle Sizer (APS) operation scheme, (b) detail view with aerosol droplets crossing the overlapping beams and generating the double-crested signal.

Figure 3

(a) Experimental setup used for the particle size characterization and (b) an aerosol visualization of a nebulizer prototype.

Figure 4

(a) MMAD (µm) and (b) Da (µm) values for prototype 1 (P1) and prototype 2 (P2) as a function of the driving pressure for distilled water (H₂Od). Values are given as mean ± standard deviation.

Figure 5

(a) MMAD (µm) and (b) Da (µm) values for prototype 1 (P1) and prototype 2 (P2) as a function of the driving pressure for PFD and FC75. Values are given as mean ± standard deviation.