Esophageal pH-impedance monitoring in patients with therapy-resistant reflux symptoms: 'on' or 'off' proton pump inhibitor?

BACKGROUND: In patients with proton pump inhibitor (PPI)-resistant symptoms, ambulatory 24-h pH-impedance monitoring can be used to assess whether a relationship exists between symptoms and reflux episodes. Until now, it is unclear whether combined pH-impedance monitoring in these patients should be performed on or off PPI. METHODS: Thirty patients with symptoms of heartburn, chest pain, and/or regurgitation despite PPI twice daily underwent ambulatory 24-h pH-impedance monitoring twice, once on PPI and once after cessation of the PPI for 7 days. The order of the measurements was randomized. Reflux episodes were identified and classified as acid, weakly acidic, or weakly alkaline reflux. In addition, the symptom association probability (SAP) was calculated for each measurement. RESULTS: The total number of reflux episodes and proximal extent were not affected by PPI therapy. On PPI, there were fewer acid reflux episodes (49 +/- 34 off PPI vs 20 +/- 25 on PPI) while more weakly acidic reflux episodes were identified (24 +/- 17 off PPI vs 48 +/- 31 on PPI). Symptom association analysis identified 15 and 11 patients with a positive SAP in the measurement off and on PPI, respectively, the difference in yield of the SAP not being statistically significant. Eight of the 19 patients who had no symptoms or a negative SAP during measurement on PPI had a positive SAP off PPI therapy. In contrast, only 4 patients with a positive SAP on PPI were missed in the measurement off PPI therapy. CONCLUSIONS: In order to demonstrate or exclude GERD in patients with PPI-resistant symptoms, ambulatory 24-h pH-impedance monitoring should preferably be performed after cessation of PPI therapy because this approach seems to offer the best chance to assess a relationship between symptoms and reflux episodes