DUAL BRAVO PH MONITORING: A Feasibility Trial

24-hour pH monitoring is often considered the "gold standard" in the diagnosis of GERD and is increasingly utilized in patients with extra-esophageal symptoms (1). However, the clinical utility of pH monitoring in this patient population remains controversial. An important limitation of traditional pH catheters is their suboptimal sensitivity especially in patients with extraesophageal GERD. Vaezi et al. tested reproducibility and reliability of the proximal and distal esophageal pH probe in 32 patients (2). Among these patients,11 were controls, 10 had distal reflux, and 11 had both proximal and distal reflux. In this group of patients the sensitivity of distal and proximal pH probes were 70% and 55%, respectively. Additionally, a more recent study by Shaker et al. showed the number and duration of hypopharyngeal reflux events to be similar between the control subjects and patients with reflux laryngitis and vasomotor rhinitis (3).

Poor sensitivity of catheter based pH monitoring in detecting acid reflux may be due to day to day variability of test, its less than adequate reliability as well as possible intermittent nature of the reflux events (not recorded in only a 24-hour period) (4). Additionally, since the traditional ambulatory device is commonly placed transnasally through the oropharynx into the esophagus, patients often complain of throat and nose discomfort and usually restrict their daily activity. This potentially leads to false negative findings and reduced test sensitivity. Furthermore, incorrect results may be collected if the pH electrode slips away from the initial manometrically determined placement site. In light of these limitations, a new wireless (catheter free) pH monitoring device was developed to improve patient comfort and increase test sensitivity. The Bravo pH monitoring system (Medtronic Inc, Minneapolis, MN) uses a radiotelemetric capsule temporarily attached to the esophageal mucosa which transmits pH data to a receiver carried on patient's belt.

Although well studied in the distal esophagus, there are currently no studies in adults assessing the feasibility and patient tolerance to placement of this device more proximally. Such a placement may increase the sensitivity of the test and add to our ability to study potential predictors of treatment response in patients with extraesophageal GERD.