AJP - Gastrointestinal and Liver Physiology, Vol 269, Issue 5 653-G658, Copyright © 1995 by American Physiological Society
Influence of gravity and body position on normal oropharyngeal swallowing
F. Johnsson, D. Shaw, M. Gabb, J. Dent and I. Cook
Department of Surgery, Royal Adelaide Hospital, South Australia.
The influence of gravity, if any, on pharyngeal bolus transport is unknown.
The aim of the present study was to evaluate the effect of gravity and body
position on the radiological and manometric events during the normal
oropharyngeal swallow. In eight healthy male volunteers, we performed
simultaneous videoradiography and manometry, using a manometry catheter
incorporating a perfused sleeve measuring upper esophageal sphincter
pressure and three solid-state transducers recording pharyngeal pressures.
Swallows of 5 and 10 ml of barium were performed in three different body
positions: upright, horizontal, and 30 degrees head down (inverted).
Hypopharyngeal intrabolus pressure increased significantly in the
horizontal and inverted positions compared with upright, P = 0.0001. This
resulted in increased maximal sphincter diameters during bolus flow (P =
0.0001) and shorter duration of sphincter opening (P = 0.03). As a result,
transsphincteric flow increased in the horizontal and inverted positions, P
= 0.04. Total swallowing duration, oral and pharyngeal transit time,
pharyngeal peristaltic amplitude and duration, the length of the bolus in
the pharynx, and excursions of the hyoid and larynx were unaffected by body
position. We conclude that intrabolus pressure is an important determinant
of upper esophageal sphincter opening in the healthy oropharynx and that
gravity does not influence pharyngeal bolus transport. The healthy upper
esophageal sphincter has residual opening capacity that can be demonstrated
by altering body posture.
