Mechanisms of gastric and supragastric belching: a study using concurrent high-resolution manometry and impedance monitoring.

BACKGROUND: Esophageal impedance monitoring has made it possible to distinguish two types of belches, designated gastric and supragastric. We aimed to compare the esophageal pressure characteristics during supragastric belches and gastric belches using combined high-resolution manometry and impedance monitoring.
METHODS: We included 10 patients with severe and frequent belching. Combined high-resolution manometry and impedance monitoring was performed. KEY
RESULTS: Whereas gastric belching was relatively rare in all patients (median incidence 2 per 90-min period), nine of the 10 patients exhibited excessive supragastric belching (36 in 90 min). Supragastric belches were characterized by: (i) movement of the diaphragm in aboral direction and increased esophagogastric junction (EGJ) pressure, (ii) decrease in esophageal pressure, (iii) upper esophageal sphincter (UES) relaxation, (iv) antegrade airflow into the esophagus, and (v) increase in esophageal and gastric pressure leading to expulsion of air out of the esophagus in retrograde direction. In contrast, gastric belches were characterized by: (i) decreased or unchanged EGJ pressure, which was significantly lower than during supragastric belches, (ii) absence of decreased esophageal pressure preceding entrance of air into the esophagus (iii) retrograde airflow into the esophagus, (iv) common cavity phenomenon, and (v) upper esophageal sphincter relaxation after the onset of the retrograde airflow. CONCLUSIONS & INFERENCES: In gastric belching UES relaxation is a late event, allowing efflux of air that entered the esophagus from the stomach. In most patients with supragastric belching air is brought into the esophagus by movement of the diaphragm in aboral direction, creation of negative esophageal pressure, and UES relaxation.