Esophageal impedance recording: clinical utility and limitations.

Multichannel intraluminal impedance (MII) is a new technique available for the evaluation of esophageal bolus transit and reflux similar to barium swallow, but without the hazards of radiation exposure. Combined MII and pH monitoring (MII-pH) allows evaluation of the nature and pH of the refluxate and the proximal extent of a reflux event. Thus, MII-pH is useful in evaluation of nonacid reflux in patients with persistent typical or atypical symptoms of gastroesophageal reflux disease that are refractory to acid suppression therapy. Additionally, combined MII and esophageal manometry (MII-EM) affords concurrent assessment of esophageal function (bolus transit) and motility. Therefore, it provides a more complete esophageal function test than esophageal manometry alone. The few limitations of impedance monitoring include the complexity of interpreting the tracings and the lack of data in the diseased population. However, continued improvements in the software and increasing studies in different patient populations will aid in overcoming these limitations.