[Influence of the viscosity of the swallowed food bolus on the motility of the pharynx].

In 9 young men, healthy volunteers, we studied the effect of dry swallows, liquid and paste swallows on the pharyngeal motility. The viscosities of liquids and past were 200 centipoise (cP), 300 cP and 60000 cP, respectively. The bolus volume was 10 ml. For pharyngeal manometry we used two strain-gauge manometric probes taped together, so that a total of six transducers were staggered at 1.5 cm intervals. After its passage through the nose, the assembly was positioned so that all its transducers faced posteriorly, and manometric activity was recorded from oropharynx, hypopharynx and upper esophageal sphincter (UES). We also recorded infra-hyoid electromiographic activity. The amplitude and duration of the oropharyngeal and hypopharyngeal peristaltic pressure complex were not changed by the different boluses. The velocity of peristaltism propagation between oropharynx and UES was slower for paste than for liquids or dry swallows. The increased of viscosity was associated with longer duration of UES relaxation, and greater intrabolus pressure in hypopharynx and UES. The infra-hyoid electromiographic activity was longer for paste than for liquids or dry swallows. These findings suggest that pharyngeal motility is affected by the characteristics of the swallowed bolus.