Effect of Body Position on Pharyngeal Swallowing Pressures Using High-Resolution Manometry

Abstract

The effect of body position and gravitational pull on the complex pressure-driven process of pharyngeal swallowing remains unknown. Using high-resolution manometry (HRM), this study aims to identify positional adaptations of pharyngeal physiology by evaluating swallowing pressure patterns in a series of inverted body positions. Ten healthy adults each underwent swallowing tasks with pharyngeal HRM at six body positions using an inversion table (0°[upright], 45°, 90°[supine], 110°, 135°, and 180°[fully inverted]). Repeated measures ANOVA was used to assess impact of position on pressure parameters, and pharyngeal-UES pressure gradients translate. Velopharyngeal pressures varied by position (P < 0.001), with significantly higher pressures generated with inversion ≥90°, compared with upright and 45°. Change in position did not significantly affect common mesopharyngeal pressures or swallowing pressure durations. UES valving mechanisms were preserved during inversion, with subtle variations observed in integral pressures (P = 0.011). Pharyngeal-UES pressure gradients changed with position (P < 0.01), increasing with inversion > 90° compared to upright and 45°. Mechanisms of deglutition may differ with position and relative direction of gravity, particularly when at > 45° inclination. Increased palatal pressure is generated in the upside-down position to achieve nasopharyngeal closure and prevent regurgitation. While other classically measured pressures may not consistently differ with positioning, many individuals exhibit adaptations in pressure gradients when inverted, likely due to a combination of changes in pharyngeal driving force and UES opening mechanisms. Identification of these changes, relative to position, further builds on our understanding of the adaptability of the pharyngeal swallowing system.

Pharyngeal swallowing mechanics associated with upper esophageal sphincter pressure wave

“…[6][7][8] Existing literature describes the UES pressure wave during swallowing as an elevated resting (basal) pressure, a period of low pressure (relaxation), a post-deglutitive increase in pressure, and a return to resting pressure. 14 However, although these elements of UES opening have been documented in the literature, the swallowing mechanics underlying the generation of the HRPM UES pressure wave, particularly why there is an elevation of pressure prior to relaxation, have not been fully investigated. Omari et al also revealed how changes in mechanical states can be deduced by recording changes in pressure and diameter within the HRPM UES region.…”

“…13 Other variables that affect the timing and magnitude of the pressure wave include bolus volume 5,12 and body position. 14 However, although these elements of UES opening have been documented in the literature, the swallowing mechanics underlying the generation of the HRPM UES pressure wave, particularly why there is an elevation of pressure prior to relaxation, have not been fully investigated.…”

Pressure abnormalities in patients with Zenker's diverticulum using pharyngeal high‐resolution manometry

“…UES residual pressure , measured at the time point of maximum tongue base pressure, was extracted as a measure of downstream resistance during pharyngeal contraction 26 . Mean preswallow baseline pressure , captures UES resting pressure over a one‐second interval, 2 seconds before pre‐opening maximum pressure 23 . The following previously described UES regional parameters were also evaluated: maximum pre‐opening pressure , maximum postclosure pressure , nadir pressure (averaged over 0.25 seconds) , and nadir pressure duration 16,23,25 …”

A review of the approaches to predict the ease of swallowing and post-swallow residues

“…Wong et al (Wong et al, 2017) showed that the trajectory of the hyoid bone and the extent of larynx elevation in different subjects are adapted to maximize airway protection. The pressures generated in the velopharynx were found to be dependent on the body position (Rosen et al, 2017). From an engineering perspective, four main alternative swallowing control scenarios can be envisaged: -imposed displacements (with no control) -imposed forces (with no control) -355 feed-forward control adapting the applied forces or displacements to the bolus characteristics perceived before the swallow -feedback control during swallowing, adapting forces or displacements…”