Ingested acidic food and liquids may lead to misinterpretation of 24-hour ambulatory pH tests: focus on measurement of extra-esophageal reflux.

Normal values of extra-esophageal reflux are difficult to determine owing to variation in the location of the proximal electrode, limited information on the ingestion of acidic food, different exclusion periods for meals, and poor reproducibility of measurement of extra-esophageal reflux. We studied whether ambulatory esophageal pH testing is disturbed by acidic food ingestion. Eighteen healthy subjects were enrolled in standard dual-channel esophageal pH tests (recorder 1). Ten subjects were equipped with another pH device (recorder 2), positioned to measure extra-esophageal reflux. The subjects were exposed to controlled ingestion of different acidic food or liquid for five 1-min periods. The present study showed that acidic food ingestion for 5 min has a significant effect on the outcome of standard dual-channel ambulatory pH testing. Reflux occurs equally on proximal channels during ingestion of acidic food, whether the proximal channel position is normal or 2 cm above the upper esophageal sphincter. We recommend avoiding acidic food intake during esophageal pH testing.