Changes of Timing Variables in Swallowing of Boluses With Different Viscosities in Patients With Dysphagia

ObjectivesTo evaluate the timing of the swallowing process and the effect of bolus viscosity on swallowing.DesignProspective observational study.SettingGeneral teaching hospital, rehabilitation unit.ParticipantsWe enrolled patients with dysphagia (n=82) in a videofluoroscopic swallowing study (VFSS) from January 13, 2009, to October 22, 2009. Based on VFSS results, we classified patients as “thin-fluid aspirators” (n=40) or as “nonaspirators” (n=42).InterventionsSwallowing of a 5-mL thick bolus and a 5-mL thin bolus in all patients.Main Outcome MeasuresKinematic analysis of various variables during the swallowing process (pharyngeal phase), including epiglottis contact with the bolus, laryngeal elevation, pharyngeal constriction, and upper esophageal sphincter opening.ResultsIn both groups, the thin bolus arrived at the vallecular pouch earlier than the thick bolus. During swallowing of the thick bolus, the thin-fluid aspirators had a delayed latency of upper esophageal sphincter opening, delayed laryngeal elevation to peak level, and significantly longer rise time of laryngeal elevation.ConclusionsOur results indicate clear differences in the degree of adaptation to bolus viscosity between patients classified as thin-fluid aspirators and as nonaspirators. These differences were mainly in activities of laryngeal elevators rather than pharyngeal constrictors.