Day to Day Discrepancy in Bravo Capsule Ph Monitoring: The Impact of Manometric Placement and Status of Lower Esophageal Sphincter

Introduction: The wireless esophageal pH monitoring (Bravo Capsule) is better tolerated and allows longer period of recording (2 days or more) in patients evaluated for gastroesophageal reflux disease. The use of this system may result in day to day discrepancy in measurement of distal esophageal acid exposure. This variation is thought to be due to the sedation used during the endoscopy for trans-oral placement of the capsule. An alternative is placing the capsule trans-nasally 5 cm above the upper border of the lower esophageal sphincter determined by manometry. We decided to assess if this method of placement, affects day to day discrepancy and if so, did the variability depend on the status of the gastroesophageal barrier.
Material and methods: Study population consisted of those who had Bravo capsule placed based on manometric measurements and had complete 2 days of pH recording. The esophageal pH monitoring components and composite pH score were compared between day 1 and day 2 using Mann-Whitney U test. The Spearman test was used to assess the correlation. In a separate analysis the study population was divided into 3 groups based on their composite pH score:
(1) Normal score on both days, (2) Abnormal score on both days and (3) Those with discrepancy between day one and day two. Lower esophageal sphincter characteristic were compared between these three groups.
Results: The study population consisted of 310 patients with a median age of 52 (IQR:42-63). No significant difference was found between day 1 and day 2 composite pH score (13.1, 14.4, p=0.66), this was also true for all the esophageal pH monitoring components (p>0.17). A strong correlation was found between composite pH score in day 1 and day 2 [r = 0.83 (95% CI: 0.79 – 0.86, p<0.0001)]. The composite pH score was normal on both days in 127(41%) patients and abnormal on both days in 123(40%). Sixty (19 %) patients had a discrepancy in their composite pH score between the two days (27 abnormal day 1 and 33 abnormal day 2).
Patients with abnormal esophageal acid exposure on both days tended to have more defective LES compared to those with abnormal pH score only in one day and those with normal composite pH score on both days. (51.2 %, 33.3%, 17.2%, p= 0.027). The LES pressure, overall length and intrabdominal length were significantly higher in patients with normal pH score in both days, compared to patients with discrepancy and those with abnormal pH score in both days (p<0.0001).
Conclusion: Manometric placement of the Bravo capsule results in less day to day discrepancy in pH recording compared to previously reported placement via endoscopy. Patients with abnormal pH on both days tend to have a greater prevalence of defective LES than those with abnormal score only on one day. The variability between the 2 days may represent impairment of gastroesophageal barrier in patients with early reflux disease.

Session: Podium Presentation

Program Number: S075