Investigation Into Nasal Saline Irrigation Within a Healthy Human Nose

Abstract

Nasal saline irrigation is a therapy that bathes the nasal mucosa with a liquid saline solution to treat inflammatory nasal and paranasal disease or manage post nasal and sinus surgery recovery. Saline irrigation is thought to improve nasal airway surface liquid (ASL) hydration and mucociliary transport. Also, it has previously shown that mechanical factors, including cyclic pressure and wall shear stresses distribution, may positively influence mucociliary clearance. A detailed saline flow analysis within the nasal cavities and maxillary sinuses during saline irrigation in various head positions and side directions, in the presence of a nasal cycle geometry, has not previously been investigated. Knowledge of the saline flow fields within the nasal cavities and maxillary sinuses during nasal saline irrigation is essential to an understanding of how different head positions and side directions affect the targeted delivery site, and whether the irrigant has the potential to stimulate the mucociliary functions at different regions of the nasal cavities and maxillary sinuses. In this thesis the distribution and pressure of the irrigant, and the mucosal wall shear stress in the human nasal cavities and maxillary sinuses, have been mapped during nasal saline irrigation using computational fluid dynamics (CFD) simulations in the presence of the nasal cycle at four different head positions: Mygind (lying with head back), 90° (tilting the head sideways at 90°), head back (head is oriented 45° upward from the ground), and head forward (head is inclined downwards at 45° to the ground). Particle image velocimetry (PIV) measurements have been applied to confirm the validity of the numerical methodology used in this study. Close agreement was found between numerical and experimental results performed under identical conditions and geometries.

New findings of this study have shown that saline irrigation at different head positions and side directions results in different saline distribution and saline pressure and mucosal wall shear stress distribution. The findings of this study will allow both clinicians and patients to make better-informed decisions on optimal irrigation techniques to better realise the full benefits of this form of treatment.