There doesn't seem to be any mention of Pulsatile Irrigation ie:
Grossan Nasal Irrigation System which might pump the solution deeper.
Also, adjusting the posture so as to allow the saline to penetrate
deeper in a certain direction is another possibility.  All the same,
it will be interesting to see what kind of technique such as the
spacer used for inhalers this study may inspire.  Judy J