Influence of Full-body Water Immersion on Esophageal Motor Function and Intragastric Pressure

BACKGROUND/AIMS: In Japan, it is customary to take a daily bath during which the body is immersed in water to the neck. During full-body immersion, hydrostatic pressure is thought to compress the chest and abdomen, which might influence esophageal motor function and intra-gastric pressure. However, whether water immersion has a significant influence on esophageal motor function or intragastric pressure has not been shown. The aim of this study was to clarify the influence of full-body water immersion on esophageal motor function and intragastric pressure. METHODS: Nine healthy male volunteers (mean age 40.1 ± 2.8 years) were enrolled in this study. Esophageal motor function and intragastric pressure were investigated using a high-resolution 36-channel manometry device. RESULTS: All subjects completed the study protocol. Intragastric pressure increased significantly from 4.2 ± 1.1 to 20.6 ± 1.4 mmHg with full-body water immersion, while the lower esophageal high pressure zone (LEHPZ) value also increased from 20.5 ± 2.2 to 40.4 ± 3.6 mmHg, with the latter being observed regardless of dietary condition. In addition, peak esophageal peristaltic pressure was higher when immersed as compared to standing out of water. CONCLUSIONS: Esophageal motor function and intragastric pressure were altered by full-body water immersion. Furthermore, the pressure gradient between LEHPZ and intragastric pressures was maintained at a high level, and esophageal peristaltic pressure was elevated with immersion.