Ambulatory esophageal pH monitoring using a wireless system

Limitations of catheter-based esophageal pH monitoring are discomfort, inconvenience, and interference with normal activity. An alternative to conventional pH monitoring is the wireless Medtronic Bravo pH System. The aim of this study was to evaluate the safety, performance, and tolerability of this system.

A total of 44 healthy subjects and 41 patients with gastroesophageal reflux disease (GERD) were studied for a 2-day period. The pH telemetry capsule was positioned transorally 6 cm above the squamocolumnar junction using endoscopic measurement. The signal transmitted from the capsule was received and recorded by a small, pager-sized receiver, and pH data were subsequently uploaded to a computer for analysis.

Successful 24-h pH studies were completed in 82 subjects (96%). During the 24-h study period the median percentage of the time that pH was <4 was 2.3% (95th percentile, 5.9%) in controls and 6.5% (range, 0.8-27.6) in GERD patients. In 76 subjects (89%), 36-48 h recordings were obtained. For the extended period the median percentage of the time that pH was <40 was 2.0% (95% percentile, 5.3%) in controls and 6.6% (range, 1.0-26.7) in GERD patients. Capsules required endoscopic removal in three subjects (4%). Optimal sensitivity in distinguishing controls from reflux patients was achieved when analyzed from the perspective of the worst of the 2 days.

The wireless Bravo pH System successfully recorded esophageal acid exposure in 96% of the patients during a 24-h period and in 89% of subjects for >36 h. The 95th percentile for the 2-day recordings in control subjects was 5.3%, slightly higher than observed with conventional systems.