Originally Posted by NOPD

The nasal cavity and sinuses are lined with a ciliated pseudostratified columnar epithelium, interspersed with goblet cells. The healthy sinonasal lining excretes approximately 1,000 mL of secretions every day. In the normal state, these secretions are carried from the sinuses into the nose, and then pass posteriorly to the nasopharynx to be swallowed. This transport is dependent upon efficient movement of the mucus by the epithelial cilia. Ciliary beat frequency, ciliary coordination, and mucus rheology are important determinants of mucociliary transport time through the nose.37 Acute and chronic rhinosinusitis, viral URI, and AR are thought to depress the normal mucociliary apparatus, leading to less efficient flow of mucus from the sinuses and nasal cavity, resulting in stagnation of secretions and increased risk of secondary bacterial infection.38

The exact mechanism of SNI is not well understood and is likely multifaceted. However, SNI has been reported to have several physiological effects that individually or in concert may result in improved function of the nasal mucosa. SNI may enhance the ability of the nasal mucosa to reduce the potential for infection and the pathologic effects of inflammatory mediators and triggers of AR, asthma, and other acute and chronic mucosal reactions. These SNI effects include the direct cleansing effect of the irrigant,39-41 reduction or removal of inflammatory mediators,10,42 and improved mucociliary function, demonstrated by increased ciliary beat frequency in the presence of hypertonic or normal saline37,43