Computational fluid dynamics for investigation of saliva pressure in parotid obstruction

OBJECTIVES/HYOTHESIS: Parotid obstruction is one of the most common problems affecting the parotid gland. We aimed to investigate the blockage ratio (BR) and the intraductal pressure change of Stensen's duct using computational fluid dynamics.

Retrospective review of 16 patients who had undergone interventional sialendoscopy for parotid obstruction from 2009 to 2011.

The three-dimensional configurations of Stensen's duct were reconstructed from computed tomography (CT) sialographic images. Finite volume modeling in fluid dynamics of parotid obstruction was used to analyze the pressure distribution under conditions of rest and stimulation.

Intraductal pressure increased with increasing distance from the orifice. The upstream pressure was higher than that of downstream pressure in the same BR (P < .05). The upstream pressure increased as the BR increased. Statistically, the pressure turning point was indicated when BR = 60%. Only when the BR was much greater than 90% did the pressure reach 811.64 Pa, at which point patients could feel the painful swelling under the rest condition. Under the stimulated condition, the upstream pressure increased from 1.3- to 2.9-fold of that of the no blocking state when the BR increased from 80% to 90%, which may aggravate the obstructive symptoms. There was no significant difference observed for downstream pressure under the same condition (P > .05).

CT sialography was effectively used for analysis of the intraductal pressure distribution in patients with parotid obstruction. Analysis of salivary fluid dynamics in Stensen's duct may provide a further pathophysiological mechanism for obstructive diseases.