Saliva transport to the distal esophagus

During esophageal acid clearance, saliva should reach the most distal esophagus. The mechanisms responsible for saliva transport are not completely understood but it is assumed that normal peristalsis plays a significant role. The aim of this study was to assess the role of esophageal peristalsis and gravity in saliva transport to the distal esophagus.

Esophageal transit and presence times of a 2-ml bolus of radiolabeled artificial saliva were assessed using concurrent scintigraphy and manometry in 10 healthy volunteers in the upright and supine positions before and after disruption of esophageal motility with sildenafil (50 mg).

With normal peristalsis, there was no difference in saliva transit to the distal esophagus between supine and upright positions 3.9 (1.5- >60.0) versus 3.3 s (1.3-8.3). Low amplitude contractions did not affect saliva transit but the disappearance of contractions after sildenafil was associated with prolonged saliva transit in supine position 7.4 (1.0- >60.0). Saliva presence time was significantly prolonged in both the upright and supine positions by esophageal dysmotility.

Saliva transport to the distal esophagus does not require complete normal peristalsis or gravity and mainly depends on an efficient pharyngeal pump. However, subjects in supine position with severe esophageal dysmotility might have both impaired volume clearance and delayed saliva transport, leading to abnormal acid clearance and esophagitis.