Efficacy for aspiration prevention through thickening of liquid foods evaluated using a swallowing model apparatus

Abstract An apparatus simulating the swallowing process of liquid foods was constructed using a flow channel. In the channel, a circular cylindrical obstruction was fixed to serve as an epiglottis in the mesopharynx. The apparatus was designed with an adjustable gate for flow control to represent the processes of healthy swallowing and dysphagia. The parameters considered were the holding time and flow resistance controlled by the gate, which were assumed to indicate the swallowing reflex and power, respectively. When a Newtonian liquid with relatively low viscosity was used, the flow experiment performed using the apparatus under conditions of shorter holding time and larger flow resistance successfully reproduced a phenomenon similar to aspiration in a patient with dysphagia. In addition to a Newtonian liquid with high viscosity, non-Newtonian liquids thickened to various concentrations using commercially available thickeners were used. In flow experiments with these test liquids, the efficacy for aspiration prevention was inferred based not only on the viscosity of the liquid but also its elasticity, depending on its viscosity.