Technology review: Esophageal impedance monitoring.

Intraluminal impedance monitoring is a new technique that can be used to detect the flow of liquids and gas through hollow viscera. In combination with manometry, it is used for esophageal function testing and while manometry provides information on contractile activity, impedance provides information on esophageal bolus transit. This is especially useful in patients with nonobstructive dysphagia. However, impedance monitoring appears to be less suitable for the evaluation of patients with achalasia. When used in combination with esophageal pH monitoring, impedance monitoring makes gastroesophageal reflux monitoring more complete because it allows recognition of both acidic and weakly acidic reflux episodes. The results of several studies suggest that impedance-pH monitoring is useful in the evaluation of patients with PPI-resistant typical reflux symptoms, chronic unexplained cough, excessive belching, and rumination.