Realistic computer simulation of bolus flow during swallowing

Abstract

In this study, swallow simulation, Swallow Vision ®, was used to estimate the velocity, shear rate, and viscosity of food during swallowing. The subjects were a healthy young person and an elderly patient with aspiration. The test food was a Newtonian fluid (viscosity 2.5 mPa･ s) and a non-Newtonian fluid (viscosity 300 mPa･s at a shear rate of 50 [1/s]). A realistic numerical organ model was created based on Computed Tomography and Video-fluorography while swallowing the test food, and the bolus flow was analyzed using a numerical model whose validation was evaluated.Consequently, in the analysis of a model in which a healthy person swallowed the Newtonian fluid, the median velocity of the bolus flow changed in the range of 0.2–0.6 m/s, and there was a bimodal peak. The median shear rate ranged from 75 to 200 [1/s], and there were three peaks. In the swallowing of the non-Newtonian fluid, the flow velocity smoothly changed between 0.1 and 0.5 m/s, the shear rate varied between 50 and 100 [1/s], and the average of the median values during the entire swallowing process was 78 [1/s].The trajectory analysis of the simulation model of the dysphagia patient demonstrated that the aspirated particles flowed faster than the non-aspirated particles.These results indicate that the numerical simulation based on medical images can analyze the bolus flow during swallowing, although there are still issues to be solved.