Background: Barostat is the only technique that allows assessment of gastric tone in humans. Our aim was to simultaneously assess gastric emptying and relaxation in response to a liquid meal.
Methods: Gastric tone was monitored using an electronic barostat in six healthy subjects after three liquid meals (200 mL, 400 mL, 600 mL, 1 kcal/mL). Scintigraphic imaging was obtained by using double isotopic labeling (technetium 99m for liquid of the 200 mL meal and xenon 133 for air into the barostat).
Results: Profound gastric relaxation was detected in every subject. The duration of proximal gastric relaxation increased with meal size. The proximal stomach remained relaxed through the duration of gastric emptying. Gastric tone returned to the fasting values simultaneously with completion of liquid emptying. Repeated measures after the 200-mL meal showed that amplitude (i.e., maximal volume change) and duration of relaxations were reproducible. However, the presence of the bag slightly accelerated gastric emptying and modified the intragastric distribution of the meal.
Conclusions: The barostat is a sensitive and reproducible technique to measure gastric relaxation following liquid meals in humans. The results also suggest that the role of gastric tone as the driving force of gastric emptying of liquids has been overestimated.