Gastroesophageal reflux in achalasia. When is reflux really reflux?

An abnormal score during 24-hr esophageal pH monitoring in achalasia may be associated either with a slow steady drift to below pH 4, or else multiple sharp dips characteristic of typical gastroesophageal reflux. To test the hypothesis that the former pattern was due to food fermentation and not reflux, samples of chewed bland food (N = 22) were incubated with saliva at 37 degrees C for 24 hr and the pH monitored (in vitro study). Further, the pH tracings of 20 patients with achalasia before operation and 12 patients after operation were studied (in vivo study). The pH of chewed food fell to a median of pH 4.0 during incubation and in seven of 22 samples fell to below pH 4. Preoperatively, four of the five patients with an abnormal pH score showed a slow steady drift, and all of these had evidence of retained food at endoscopy. Postoperatively, three of the six patients with an abnormal pH score had a slow steady drift to below pH 4. Use of pH 3 as a threshold clearly distinguished true reflux from food fermentation, since the patients with reflux all had an abnormal percentage of time below pH 3.