Combined multichannel intraluminal impedance and pH-metry: an evolving technique to measure type and proximal extent of gastroesophageal reflux.

The accepted "gold standard" for measuring gastroesophageal reflux (GER), distal esophageal pH recording, has limited ability to measure nonacid GER, a potentially important cause of symptoms, in an era of potent acid-suppressing medications. A combination of multichannel intraluminal impedance (MII) and pH- metry offers an advantage over pH measurement alone. MII can detect GER at multiple levels of the esophagus independent of pH. In addition, use of MII enables refined characterization of intraluminal events, including presence, type (air, liquid, or mixed), and spaciotemporal characterization of a bolus. MII has the potential to become a useful clinical tool to assess ongoing reflux in patients on acid-suppression therapy.