Effect of proximal gastric volume on hiatal hernia

Background Spatial separation of the diaphragm and the lower esophageal sphincter (LES) occurs frequently and intermittently in patients with a sliding hiatus hernia and favors gastro-esophageal reflux. This can be studied with high-resolution manometry. Although fundic accommodation is associated with a lower basal LES pressure, its effect on esophagogastric junction configuration and hiatal hernia is unknown. Therefore, the aim of this study was to investigate the relationship between proximal gastric volume, the presence of a hiatal hernia profile and acid reflux. Methods Twenty gastro-esophageal reflux disease (GERD) patients were studied and compared to 20 healthy controls. High-resolution manometry and pH recording were performed for 1 h before and 2 h following meal ingestion (500 mL per 300 kcal). Volume of the proximal stomach was assessed with three-dimensional ultrasonography before and every 15 min after meal ingestion. Key Results During fasting, the hernia profile [2 separate high-pressure zones (HPZs) at manometry] was present for 31.9 +/- 4.9 min h-1 (53.2%) in GERD patients, and 8.7 +/- 3.3 min h-1 (14.5%) in controls (P < 0.001). In GERD patients, the presence of hernia profile decreased during the first postprandial hour to 15.9 +/- 4.2 min h-1, 26.5%, P < 0.01 whilst this phenomenon was not observed in controls. The rate of transition between the two profiles was 5.7 +/- 1.1 per hour in GERD patients and 2.5 +/- 1.0 per hour in controls (P < 0.001). The pre and postprandial acid reflux rate in GERD patients during the hernia profile (6.4 +/- 1.1 per hour and 18.4 +/- 4.3 per hour respectively) was significantly higher than during reduced hernia (2.1 +/- 0.6 per hour; P < 0.05 and 3.8 +/- 0.9 per hour; P < 0.05). A similar difference was found in controls. Furthermore, an inverse correlation was found between fundic volume and the time the hernia profile was present (r = -0.45; P < 0.05) in GERD patients, but not in controls. Conclusions & Inferences (i) In GERD patients a postprandial increase in proximal gastric volume is accompanied by a decrease in hernia prevalence, which can be explained by a reduction of the intra-thoracic part of the stomach. (ii) A temporal hernia profile also occurs in healthy subjects. (iii) During the hernia profile, acid reflux is more prevalent, especially after meal ingestion.