Analysis of the gastric acid pocket

Gastro-esophageal reflux is a common phenomenon in which gastric contents flow
back into the esophagus. When reflux causes symptoms and/ or esophageal damage,
it is referred to as gastro esophageal reflux disease (GERD), which is a very
common chronic condition.
Most reflux episodes occur after a meal, when the stomach is filled. Until
recently, it was thought that gastric contents mix well after a meal. However,
already soon after a meal highly acidic reflux episodes occur. Fletcher et al
have shown that an unbuffered pool of acid floats on top of the meal in the
proximal stomach, which explains the acidic reflux after a meal, and this they
have called the gastric acid pocket. Recently, our lab has shown that the
position of the acid pocket in relation to the crural diaphragm mainly
determines the acidity of the refluxate. In patients with GERD, the fluid of
the gastric acid pocket is located above or at the level of the diaphragm, and
is then the most important source of the refluxate. In a substudy, we have
shown that it is possible to obtain the fluid of the acid pocket by applying
suction via a gastric tube. Thereby, suction of the pocket enables us to
analyze the composition of the refluxate, which is of importance in the
generation of symptoms and/or mucosal damage.
Until now, the acidity and localisation of the pocket are the only factors that
have been studied. Factors in refluxate that are known to cause either symptoms
or mucosal damage, are pepsin, trypsin and bile acids. The composition of
gastro-esophageal refluxate has been analyzed before. In this study, it was
shown that acid and pepsin in refluxate were the most important predictors of
mucosal damage. Nowadays, patients with GERD have potent acid suppressive
therapy, which was unavailable at the time of this study. Acid suppressive
therapy leads to less acid reflux, and probably to inactivity of pepsin.
Currently, a study is conducted in which the acid pocket composition in
patients with acid suppressant resistant symptoms is analyzed. (MEC 10/037) To
compare data to patients with GERD, the data from this study in healthy
volunteers will be used.
Furthermore, although frequently used therapies like antacids and alginates are
thought to influence the gastric acid pocket, this has not yet been studied.
Analysis of the fluid of the gastric acid pocket will be used to come to a
reliable in vitro model of the acid pocket. Using an in vitro model, the
influence of current therapies can be evaluated and potential new therapies can
be tested.

To obtain fluid from the the gastric acid pocket to:
1.) Compare fluid of patients on ppi, patients with Barrett's esophagus and
volunteers
2.) to assess the properties of the fluid to develop a reliable in vitro model

This is a non-therapeutic study

the burden is limited to one study visit in which a scintigraphy and suction
via an inserted gastric tube is performed. Risk is limited, but there is
radiation exposure and the the introduction of the gastric tubes.