Reflux Testing in the 21st Century: Is There a Role for pH Only?

In November 2002, a group of international experts met in Porto, Portugal for the express purpose of critically evaluating the available techniques to measure gastroesophageal reflux (GER). The consensus conclusion from this “Porto Meeting” was that “impedance monitoring is the most sensitive test for the detection of all types of reflux.”¹ This raised the question of whether it would become the new gold standard for GER monitoring. During the subsequent 5–6 years, there have been numerous studies showing that impedance changes recorded at multiple sites within the esophagus can identify postprandial reflux of a non-acid or “weakly acidic” nature that was undetected by an accompanying pH electrode in patients both on and off proton pump inhibitor (PPI) therapy. In addition, studies with ambulatory monitoring with combined multichannel intraluminal impedance and pH (MII-pH) for up to 24 hours in patients with persistent gastroesophageal reflux disease (GERD)–related symptoms have confirmed that considerable reflux having a pH >4.0 can be identified, and that a positive association of non-acid reflux with symptoms occurs in 30%–40% of patients identified as “PPI failures.”