Review article: oesophageal pH monitoring--technologies, interpretation and correlation with clinical outcomes

Using a simple 'test' to diagnose gastro-oesophageal reflux disease is difficult because accurately measuring gastric refluxate and correlating reflux events with symptom episodes is complex. This paper reviews the safety, tolerability and diagnostic accuracy of Bravo (Medtronic, Shoreview, MN, USA), ambulatory oesophageal pH monitoring technology. Catheter-based pH electrodes inhibit patients' normal activity, and can yield erroneous results because of placement or subsequent migration of the probe or errors in the thermal compensation algorithm that is requisite for antimony pH electrodes. Bravo pH studies reliably discriminated oesophagitis patients from controls, but are less discriminatory in endoscopy-negative gastro-oesophageal reflux disease patients. The Bravo system can be accurately placed using endoscopic landmarks and pH studies demonstrated more accurate in vivo pH recording than with a catheter-based system. The Bravo system detected fewer reflux events of short duration compared with a catheter-based system. Studies examining the correlation between reflux events and symptoms have not yet been conducted using the Bravo system. In conclusion, the Bravo system offers a more user-friendly ambulatory pH monitoring technique that more accurately records pH compared with a catheter-based system. More research is needed to determine whether the detection of reflux events with Bravo will provide a good correlation with symptom episodes.