Pharyngeal Pressure and Timing During Bolus Transit

Abstract

Determining intrabolus pressure (IBP) at the upper esophageal sphincter (UES) and in the esophagus has given compelling evidence that IBP can be a predictor for swallowing dysfunction. Studies have looked most superiorly at the low hypopharynx region but there has been no inquiry into what IBP measures throughout the entire pharynx can tell us. We present a study to describe the pressures within and surrounding the moving bolus throughout the pharynx and into the UES. Simultaneous high-resolution manometry (HRM) and videofluoroscopy were performed in ten healthy subjects swallowing ten 10 mL thin-liquid barium boluses. Three events surrounding bolus movement were tracked via videofluoroscopy, and two additional events were found using manometric measures. As the bolus passes through the pharynx, low pressure is created at and below the head of the bolus. A modest pressure increase is seen as the bolus passes through the pharynx, and finally, high pressure is observed at the bolus tail, followed by an even larger pressure generation of a clearance event. HRM allows for greater resolution in data collection in the pharynx and in this study, aided in identifying semi-unique characteristics around the hypopharynx and the UES which are consistent with the complex anatomy of the regions and the transition of the UES from active closure to relaxed opening. In the future, additional studies designed to look at aged and diseased populations may lead to better understanding of disease etiology, and treatment options.

Keywords: Deglutition; Deglutition disorders; High-resolution manometry; Intrabolus Pressure; Videofluoroscopy.

Fig. 1

High-resolution manometry (HRM) pressure wave and spatiotemporal plot alignment of sensor regions of a 10 mL swallow. The left side of the figure outlines the pressure wave shapes that helped us determine the regions of interest, and shows where the corresponding sensors line up on the HRM spatiotemporal plot (on the right). The pressure wave and spatiotemporal plots are time aligned along the x-axis.

Fig. 2

Visual Description of the Bolus Events on fluoroscopy stills. The Leading Bolus Point, Trailing Bolus Point and Clearance Point were each found using videofluoroscopy, and the coordinates were then used to find the corresponding pressure values. Leading Pressure was not found using videofluoroscopic techniques like the other points outlined on the stills, it is represented here as a way to better visualize the event that was measured manometrically.

Fig. 3

High-resolution manometry (HRM) sensor readings from a single 10mL swallow. Each measured pressure event is temporally displayed on each corresponding sensor of the measurement.

Fig. 4

Mid Bolus measurement was made at each sensor between the Leading and Trailing Bolus Pressure events’ timing (see Figure 3 for description of bolus events).

Fig. 5

An alternate display of the five described pressure events superimposed on the corresponding HRM spatiotemporal plot from a single swallow. Each marker indicates the timing and positioning of the event as caught on videofluoroscopy, and then aligned with HRM data. The number of markers for each event varies due to the rate of movement on videofluoroscopy. For example, the bolus head moves much more rapidly than the tail and therefore has less event specific markers.

Fig. 6

An overview of all the pressure profiles, divided out by swallowing pressure event then pharyngeal location. P = Pressure, BP = Bolus Pressure, MBP = Mid Bolus Pressure, ‘rUES’ rostral upper esophageal sphincter, and ‘cUES’ caudal upper esophageal sphincter. Within individual pressure events, significant pressure differences were observed across regions. For the leading pressure event, average pressure at the rUES was significantly greater than at the tongue base and hypopharynx. For the mid-bolus pressure event, average pressure at the tongue base is significantly greater than at the rUES and the cUES. For the trailing bolus pressure event, average pressure at the cUES is significantly greater than at the tongue base, hypopharynx, and rUES. For the clearance pressure event, average pressure at the cUES is significantly greater than at the tongue base, hypopharynx, and rUES. Error bars indicated standard error of the mean. *P < 0.05. **P < 0.01. ***P <0 .001.