Objective: To determine the effect of decreasing time intervals between acid exposures on the sensitivity of the esophageal mucosa.
Methods: Ten healthy subjects with no history of gastroesophageal reflux disease who were symptomatic during a modified Bernstein acid infusion test were recruited for the study. Hydrochloric acid solutions of pH 3, 2, and 1 were sequentially tested. The weakest pH solution that was perceived by the patient was used for the study. The same duration of acid infusions (9 ml/min for 5 min) were made but with decreasing time intervals between each subsequent acid infusion (30-0 min). Esophageal sensation during each of the infusions, the amount of distilled water required to raise intraesophageal pH > 4, and the duration of residual heartburn after pH > 4 were recorded.
Results: Seven of the 10 subjects (70%) were Bernstein-positive to pH 3, two to pH 2, and only one to pH 1 solution. The median time to initial heartburn was significantly reduced only between the initial infusion and the first subsequent acid exposure 30 min later (165 vs 51.5 s, p < 0.009). Subsequent reductions in the time interval between infusions did not significantly reduce the perception threshold. The water required to clear the esophagus to pH > 4 and time required for the residual esophageal sensation to disappear were not significantly altered throughout the study.
Conclusions: These data suggest that some episodes of reflux may be felt sooner and perhaps more severely despite similar levels of acid burden in the esophagus when sensitization by a prior reflux episode occurs.