[Effect of Bolus Volume on Pharyngeal Swallowing Dynamics Evaluated with Small High-Resolution Manometry Catheters]

The bolus volume has a modulating effect on the swallowing dynamics, but previously reported adaptations of the pharyngeal function have been inconsistent. Therefore, the aim of this study was to comprehensively evaluate changes of pressure and time parameters in the pharynx and upper esophageal sphincter (UES) in relation to the swallowed bolus volume with high-resolution manometry (HRM). To examine the normal swallowing physiology, particularly thin HRM probes were used, which were expected to influence the investigated structures only minimally.10 healthy volunteers accomplished 10 swallows with 2 and 10 ml water respectively in an upright position, while an HRM-examination was performed. Pressure and time parameters of the velopharynx, the tongue base region and the UES were determined and analyzed for statistical differences with respect to the bolus volume.Swallowing larger bolus volumes resulted in both, a longer closure of the velopharynx and in a longer opening of the UES. Volume dependent pressure changes in the pharyngeal swallowing sequence were not detectable.Under the chosen test conditions, bolus volume had an impact on the time parameters of the pharyngeal phase, thus, temporal adaptations of the automated swallowing dynamics were detected. Changes in pharyngeal pressure parameters as shown in other studies cannot be confirmed. They may be due to HRM probes with a larger diameter, which take an effect on the pharyngeal structures themselves. With regard to diagnostic aspects, HRM studies should always be conducted with different bolus volumes in order to investigate the swallowing process completely.