Abstract
[Objective] Aspiration observed during a videofluoroscopic swallowing study (VF) may occur subsequent to an involuntary spillage of food boluses into the pharynx. To prevent such aspiration, attempts are often made to adjust the patient's posture and modify the physical properties of food. Iida developed a videofluoroscopic swallowing simulation system using a full-scale model of the oropharyngeal cavity as the subject and examined the kinetics of a test material. In this study, we simulated an involuntary spillage of food boluses into the pharynx through postural procedures and the physical properties of food boluses using VF simulation.
[Materials and Methods] Three full-scale models of the oropharyngeal cavity were created based on conebeam CT image data of the human head. The oropharyngeal cavity in the upright, chin-down, and head rotation to the left positions was reproduced in each cylindrical plaster model. Barium contrast medium, thickened barium contrast medium, and test materials such as pudding and cream were prepared as the test materials. Physical properties of the test materials were evaluated in terms of food texture including the hardness, adherability and aggregability using a texture analyzing system. Each sample was applied onto the center, right side and left side of the tongue of the model. VF images of the bolus sliding over the base of the tongue were acquired, and the speed of the bolus and the sliding route were measured.
[Results] The sliding speed of the 90% liquid barium contrast medium was decreased by approximately 90% by adding a more than 5 W/V% thickening agent, regardless of the patient's posture. The chin-down position model provided a slower sliding speed for the liquid barium contrast medium than the other positions tested. The gel-like test materials slid more slowly than the liquid barium contrast medium but faster than the thickened liquid barium contrast medium. The upright position model and chin-down position model allowed the barium contrast medium to slide along the midline regardless of where the barium contrast medium was applied, while the left neck rotation position model caused the barium contrast medium to slide over the left side.
[Discussion] The chin-down position may be effective for controlling the sliding speed of food boluses. Rotating the neck during active swallowing may guide the food bolus toward the opposite side to which the neck is rotated. However, in case of involuntary spillage, a food bolus may slide along an unintended route.
