Changes of timing variables in swallowing of boluses with different viscosities in patients with dysphagia.

Objective: To evaluate the timing of the swallowing process and the effect of bolus viscosity on swallowing.

Methods: Prospective observational study. Methods: General teaching hospital, rehabilitation unit. Methods: We 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). Methods: Swallowing of a 5-mL thick bolus and a 5-mL thin bolus in all patients. Methods: Kinematic 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.

Results: In 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.

Conclusions: Our 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.