Another approach would be therapy guided by investigations including high resolution (HR) esophageal impedance manometry and 24-hour pH-impedance studies. Study of esophageal function has greatly evolved with the recent availability of high resolution multi-channel solid state manometer and impedance. Water swallows are commonly used in esophageal manometric studies to evaluate for peristaltic abnormalities. Esophageal pH monitoring does not detect all gastroesophageal reflux (GER) events but with the combination of impedance, this technique allows detection of GER of gas and acid or non-acid liquids. These tests would enable diagnosis of GERD and functional chest pain and thereby allow targeted therapy.