Effectiveness of Prolonged pH Monitoring Using a Catheter-Free System in Children Undergoing Upper Endoscopy

Abstract

Purpose: Ambulatory 24-hour pH monitoring with a nasal catheter is currently the gold standard for measuring esophageal pH. The Bravo pH system is a catheter-free pH testing system that measures esophageal pH up to 48 hours via a radio-transmitted capsule which is endoscopically attached to the esophageal mucosa. The ability to perform prolonged esophageal pH determination in children increases the likelihood of having symptoms during the pH monitoring period and may improve diagnostic yield. The aim of the study was to compare the reproducibility of results obtained on the first day of the study with those obtained on the second day. Methods: The medical records of all patients who underwent catheter-free pH monitoring between 10/02 and 10/03 were reviewed. In each pt the squamocolumnar junction was located endoscopically and the pH capsule was placed approximately 5 cm above the proximal border of the lower esophageal sphincter. All pts were re-endoscoped immediately following capsule placement to document attachment. After a 48 hr period the recording device was returned with the following data: study duration, # of reflux episodes, fraction of time pH<4, symptoms. Only pts with greater than one day of recorded data were included in the study. Results: 18 symptomatic pts underwent endoscopy and pH capsule placement. The probe attached in the appropriate location in 100% of cases. In 15 pts (11M,4F), mean age 13.5 ±2.8 yrs (range 8-17 yrs), data was successfully recorded for > 24 hour period. Results from day one and day two were compared using the Wilcoxon matched-pairs signed-ranks test. There was no significant difference found between the number of reflux episodes (p=0.98) or fraction of time pH<4 (p=0.84) between day one and day two. In addition, the DeMeester score was not significantly different (p=0.72) between day one and day two. Conclusion: The catheter-free pH testing system successfully recorded reflux episodes and % acid exposure for > 24 hour period in 83% of children studied. The second period of monitoring was similar to the first 24 hr period. The lack of a significant difference in results between the two days suggests that this technique may be useful in evaluating the acute response to therapeutic interventions.