Effects of body position and liquid meal ingestion on esophageal acid exposure time in healthy subjects.

We investigated the effect of body position and ingestion of a test liquid meal on esophageal acid exposure time in 20 asymptomatic healthy subjects. Intraesophageal pH monitoring was performed for 1 h before meals and 3h postprandially with the subject in the supine (n = 10) or sitting position (n = 10). The test meal had a total volume of 800 ml and an energy content of 500 kcal. Esophageal acid exposure time was defined as the percentage of time at pH < 4.0. There was no difference in preprandial or postprandial esophageal acid exposure time between the supine and sitting positions. Esophageal acid exposure time for the 3-h postprandial period was significantly greater than that for the preprandial period in both the supine and the sitting positions. The difference in body position did not influence preprandial or postprandial esophageal acid exposure time, but ingestion of the liquid meal significantly increased the esophageal acid exposure time in both the supine and sitting positions in asymptomatic healthy subjects.