Intermittent spatial separation of diaphragm and lower esophageal sphincter favors acidic and weakly acidic reflux

Background & Aims: In small hiatal hernias, the size of the hernia is variable. Intermittent complete reduction can be observed with high-resolution manometry as a transition from a double-peak (hernia) to a single-peak (reduced) high-pressure zone. The aim of this study was to investigate whether intermittent separation of the diaphragm and lower esophageal sphincter (LES) favors the occurrence of gastroesophageal reflux. Methods: In :16 patients with a small hiatal hernia (3 cm), prolonged high-resolution manometry was performed. Acid and weakly acidic reflux episodes were detected with pH-impedance monitoring. Results: The single pressure peak profile (reduced hernia) was present for 814 minutes (56.5% of total time), and the double peak profile (unreduced hernia) was present for 626 minutes (43.5% of total time). In all patients, both pressure profiles were observed. The transition rate between the 2 profiles was 7.5 +/- 0.9 per hour. More reflux occurred when the LES and diaphragm were separated versus the reduced hernia state (23.1 +/- 5.1 vs 12.2 +/- 2.4 episodes per hour, respectively; P <.05). The proportions of acidic reflux episodes during the single and double pressure peaks were similar (70% and 67%, respectively). In the two-pressure-zone state, there was an increase in all reflux mechanisms except transient LES relaxation. Conclusions: In patients with a small hiatal hernia, intermittent reduction of the hernia occurs frequently. Spatial separation of the diaphragm and LES in the nonreduced state results in a 2-fold increase in acidic and weakly acidic reflux due to mechanisms other than transient LES relaxation.