Comparison of swallowing dynamics between jelly and thickened liquid commonly used for swallowing training in Japan

This study investigated the swallowing dynamics of jelly, thickened liquid, and thin liquid in selected stroke patients who exhibited near-normal swallowing function with screening tests. Videofluoroscopic examination compared the pharyngeal transit time (PTT), pharyngeal delay time (PDT), and laryngeal elevation delay time (LEDT). Of 175 patients (104 men, 71 women; mean age: 68.6 ± 12.0 years) evaluated, 24 (13.7%) experienced aspiration, significantly prolonging LEDT in swallowing thin liquid. PTT did not differ in swallowing jelly, thickened liquid, or thin liquid among the patients who did not aspirate. However, in two-phase analysis of PTT, performed before and after the jelly passed the epiglottis, the former was significantly prolonged, whereas the latter was significantly shortened. PDT was significantly longer with jelly than with thickened and thin liquids. LEDT was significantly longer in swallowing thin liquids. Apparently, the thin liquid reached the pyriform sinus before maximum laryngeal elevation, posing a risk of laryngeal penetration and aspiration during swallowing. A thicker liquid prolonged the time taken to reach the pyriform sinus, reducing aspiration risk. Moreover, oropharyngeal passage of jelly took longer, triggering the swallowing reflex around the vallecula and allowing the jelly to pass through the hypopharynx after laryngeal closure.