Influence of body position, dry and water swallows, smoking, and alcohol on esophageal acid clearing.

Esophageal acid clearing in normal subjects was studied in different body positions, with an assessment of reproducibility, after dry and water swallows, after smoking, and after alcohol intake. A significant increase in the number of swallows to raise the distal esophageal pH to 5.0 was found in the head-down position (p less than 0.003), after smoking (p less than 0.003), and after alcohol intake (p less than 0.001). It is proposed that the outcome of the acid-clearing test reflects both the transporting capacity of the esophageal muscles and the production of saliva. The precision of the acid-clearing test is not satisfactory, which makes it unsuitable for use in individual cases. It seems, however, well fitted for evaluation of esophageal acid clearing in larger samples.