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, ρ = 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 ρ: -0.14; 10 ml, ρ: 0.18) or the paste (5 ml, p: 0.08; 10 ml, p: 0.10). The correlation between the oral transit time and the pharyngeal clearance time was not significant for the liquid bolus (5 ml, ρ: 0.31; 10 ml, ρ: 0.18), but it was significant for both the 5 ml (ρ: 0.71) and 10 ml (ρ: 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.