Particle deposition efficiency of therapeutic aerosols in the human maxillary sinus

The deposition efficiency of therapeutic aerosol particles in the human maxillary sinus is evaluated both in the human body and in a model cast of the upper airway. In the experiments, three sample materials, such as mono-dispersed polystyrene latex particles, aqueous glucose solution and pure water, in the range of particle diameter of from 0.5 to 15.8 microns, are employed in the model cast. The radioactive labelled aerosol particle is also used in the human body. From the results of the experiment, it is confirmed that even though the maxillary sinus is a closed hollow organ, aerosol flow is able to be induced only when the pressure gradient is applied between the nasal cavity and the maxillary sinus. In this case, the particle deposition is is explained in relationship to the inertia impaction of the aerosol particles on the inside wall of the maxillary sinus. The total deposition efficiencies and the deposited particle sizes in the sinus area for both experiments, with the model and in the human body, are almost the same at 3%, and 3-10 microns in diameter, respectively. A physical model for this particle deposition suggests that these experimental values change not only with the size distributions of therapeutic particles and the pressure gradient, but also with the diameter of the sinus ostium. Moreover, since the therapeutic particle might not enter the maxillary sinus when the diameter of the sinus ostium canal is less than 1 mm, some pretreatment to open the sinus ostium canal would be necessary before applying such aerosol therapy in practice.