Effect of reflux and esophagitis on esophageal volume and acid clearance in piglets

The study investigates esophageal motor function and esophageal clearance immediately after surgical induction of reflux in piglets and 8 weeks later after peptic esophagitis has developed.

Twenty-four sedated, nonintubated piglets were divided into three groups: sham (laparotomy only), reflux (distal esophageal myotomy), and reflux + esophagitis (8 weeks after myotomy). All animals underwent stationary manometry of the esophagus with a four-lumen perfused assembly after injection of 1-, 2-, and 3-mL boluses of saline and acid into the proximal esophagus. Simultaneous pH monitoring allowed assessment of acid clearance. Wave features and clearance times after saline and acid were compared among groups.

There were minor changes in peristaltic activity of the esophagus after saline boluses in animals with reflux. Acid clearance time was prolonged, especially the time to re-establish resting esophageal pH, in animals with esophagitis. These changes, which were volume-dependent, were related to the loss of peristaltic organization of the esophageal waves. The esophageal wave frequency, amplitude, and duration were only slightly changed by the induction of reflux and by esophagitis.

The esophagus affected by acid reflux, with or without esophagitis, was capable of near-normal motor responses after boluses of saline. Reflux impaired the peristaltic response to acid, and the effect was more pronounced when reflux and esophagitis were both present. The acid clearance time was also strikingly prolonged in the presence of reflux and esophagitis. The results suggest that long episodes of reflux seen on pH tracings from individuals with esophagitis might be secondary both to acid-related motor dysfunction and large volumes of refluxate.