Measurement of pepsin, an enzyme normally produced only in the stomach, has been used as a non-invasive way to detect gastric aspiration (reflux of stomach fluid into the airway) in both adults and children, but using pepsin to detect reflux has not been tested. Since pepsin should not be present in the normal esophagus and respiratory tract, but is always present in reflux fluid from the stomach, the investigators believe that the more GE reflux the investigators detect, the higher the levels of pepsin the investigators see in the fluid collected from the mouth. If patients do not have GE reflux, but have swallowing problems alone in which food or liquid goes into the airway, the investigators expect that these patients will have no pepsin in the fluid collected from their mouth.