A thin flexible tube (about the diameter of a spaghetti noodle) is directed through the nose and down the esophagus where it is positioned in the esophagus (it's not as bad as it sounds). The outside of the tube is taped to the nose and worn around for the next 24hours where it records the pH (level of acidity) and impedence (whether there is liquid present) in the lower esophagus. The person is able to eat and drink normally with it in place. The tube is then removed after 24hours and the data is analyzed. We use this to quantitate the severity of GERD. It has the advantage over the BRAVO capsule that it can record both acidic and non-acidic reflux, but the disadvantage that the person has to endure having a small tube down their nose for a day.