Alteration of esophageal peristalsis by body position.

In order to determine the effect of body position on esophageal peristalsis, normal subjects were studied by manometry in upright and supine positions. In each position, responses to a standard sequence of "dry" and "wet" swallows were recorded. Amplitudes, durations, and propagation times of esophageal contractions were uniformly greater with wet than with dry swallows. Peristaltic amplitudes were greater throughout the length of the esophagus in the supine than in the upright position. Peristaltic wave durations were relatively little influenced by body position, while propagation times were shorter in the upper esophagus but longer in the proximal half of the lower esophagus in the upright than in the supine position. All differences were more marked with wet than with dry swallows. Thus, esophageal peristalsis is significantly altered by body position, and the effect of the latter is bolus-dependent.