Bravo Capsule Placement in the Gastric Cardia: a Novel Method for Analysis of Proximal Stomach Acid Environment

Background: Intragastric pH monitoring is currently done using catheter-based pH systems. This study assessed the feasibility of proximal intragastric pH recording with the Bravo wireless pH monitoring system using novel methodology.

Methods: Nine asymptomatic volunteers and 9 symptomatic patients were studied. One pH capsule was positioned under direct endoscopic visualization so that the device straddled the squamocolumnar junction (SCJ) with the attachment well positioned on squamous mucosa and the pH electrode 1.5-2 cm distal to the SCJ. A second capsule was placed 6 cm proximal to the SCJ. The signal from each capsule was recorded by a separate receiver synchronized for time.

Results: Successful placement and interpretable recording for >42 h from both pH capsules was achieved in 16 (88%) of 18 subjects. Data capture were 98.3% in the cardia and 97.7% in the esophagus. Two failures occurred due to premature capsule detachment (one esophageal and one gastric). The acid environment in the cardia was similar in asymptomatic controls and symptomatic patients and exhibited less meal-related buffering than is typical of more distal intragastric recordings. In addition, nadir gastric cardia pH was almost always less than nadir esophageal pH during reflux events.

Conclusions: Twenty-four hour gastric cardia pH monitoring is feasible with the Bravo system and can be added to esophageal pH monitoring to assess concomitant cardia acidity. Instantaneous cardia pH defines the potential nadir esophageal pH during reflux events.