The relationship between the oral and pharyngeal phases of swallowing

OBJECTIVE: This study was designed to investigate a possible relationship between the duration of the oral and pharyngeal phases of swallowing. INTRODUCTION: The oral and pharyngeal phases of swallowing are independent from each other but may be related. METHODS: We used videofluoroscopy to evaluate 30 healthy volunteers between 29 and 77 years of age who swallowed 5- and 10-ml liquid and paste boluses in duplicate. The duration of the oral phase, pharyngeal transit, and pharyngeal clearance were measured. RESULTS: There were no differences in oral or pharyngeal transit times between the liquid and paste boluses or between the volumes of 5 and 10 ml (p>0.40). The pharyngeal clearance time for the paste bolus (0.48 +/- 0.27 s) was longer than for the liquid bolus (0.38 +/- 0.11 s, p = 0.03) with no difference between the volumes of 5 and 10 ml. There was no significant correlation between the oral transit time and the duration of pharyngeal transit for the liquid (5 ml, Spearman's coefficient rho: -0.14; 10 ml, rho: 0.18) or the paste (5 ml, rho: 0.08; 10 ml, rho: 0.10). The correlation between the oral transit time and the pharyngeal clearance time was not significant for the liquid bolus (5 ml, rho: 0.31; 10 ml, rho: 0.18), but it was significant for both the 5 ml (rho: 0.71) and 10 ml (rho: 0.64) paste boluses. DISCUSSION: The relationship between the oral and pharyngeal phases of swallowing can be affected by bolus consistency. CONCLUSION: There is a correlation between the duration of oral transit and the duration of pharyngeal clearance during the swallowing of paste boluses.