Bravo Catheter-Free pH Monitoring: Normal Values, Concordance, Optimal Diagnostic Thresholds, and Accuracy

Background & Aims: The Bravo pH capsule is a catheter-free intraesophageal pH monitoring system that avoids the discomfort of an indwelling catheter. The objectives of this study were as follows: (1) to obtain normal values for the first and second 24-hour recording periods using a Bravo capsule placed transnasally 5 cm above the upper border of the lower esophageal sphincter determined by manometry and to assess concordance between the 2 periods, (2) to determine the optimal discriminating threshold for identifying patients with gastroesophageal reflux disease (GERD), and (3) to validate this threshold and to identify the recording period with the greatest accuracy. Methods: Normal values for a manometrically positioned, transnasally inserted Bravo capsule were determined in 50 asymptomatic subjects. A test population of 50 subjects (25 asymptomatic, 25 with GERD) then was monitored to determine the best discriminating thresholds. The thresholds for the first, second, and combined (48-hour) recording periods then were validated in a separate group of 115 patients. Results: In asymptomatic subjects, the values measured using a manometrically positioned Bravo pH capsule were similar between the first and second 24-hour periods of recording. The highest level of accuracy with Bravo was observed when an abnormal composite pH score was obtained in the first or second 24-hour period of monitoring. Conclusions: Normal values for esophageal acid exposure were defined for a manometrically positioned, transnasally inserted, Bravo pH capsule. An abnormal composite pH score, obtained in either the first or second 24-hour recording period, was the most accurate method of identifying patients with GERD.