Sonographic evaluation of physiologic bolus volume in oral swallowing.

Twenty-two nondysphagic normal subjects were sonographically studied to define the average volume of a physiologic fluid bolus. Several varying volumes (5, 10, 15, and 20 ml) of water were given to assess the average size of the swallowed bolus. At the onset of oral deglutition, when placed between the dorsum of the tongue and the groove of the hard palate, the bolus has an ellipsoidal shape, thus permitting sagittal, axial, and coronal measurements. Our results indicate that swallowed bolus volume rises proportionally to water bolus given up to 15 ml and that the average size of a physiologic fluid bolus is 7 ml.