Pre- and postoperative sinus penetration of nasal irrigation.

Endoscopic sinus surgery is an accepted treatment for medically recalcitrant chronic rhinosinusitis. Effective saline douching may improve long-term outcomes of chronic rhinosinusitis but is often impaired by postoperative ostial stenosis. The aim of this study is to determine a critical ostial size at which douching solution reliably enters the sinus cavities. Prospective study of consecutive patient cohort. Seventeen preoperative or well-healed postoperative endoscopic sinus surgery patients were irrigated with 5 mL blue food coloring mixed with 200 mL buffered saline from a squeeze bottle. The degree of sinus penetration, sinus ostial patency, and ostial size were endoscopically determined. Sinuses penetrated by blue dye had a significantly larger minimal ostial dimension (7.31 mm; 95% confidence interval 5.54-9.08) than those that had no blue dye penetration (1.26 mm; 95% confidence interval 0.86-1.66) as determined by Student t test. Chi-square analysis showed that operated sinuses were more likely to be penetrated than nonoperated sinuses (P = .0016) and obstructed sinuses (P = .0325). Logistic regression showed a 95% probability of penetration when the minimum ostial dimension is 3.95 mm or greater. Unoperated sinuses or cases with gross sinus ostial obstruction will not be reliably penetrated by sinus irrigant. A 3.95-mm ostial diameter seems to be the minimum size to guarantee penetration in paranasal sinuses to maximize the potential for topical sinus treatment.