Purpose: Ambulatory pH monitoring is the gold standard for the diagnosis of GERD. Whether to perform this test off or on PPI therapy continues to be debated. With the advent of the Bravo pH system, prolonged monitoring sessions have become feasible. Recent data have shown that 96 hour studies using two separate receivers calibrated to one Bravo capsule can effectively document off (first 24 hours) and on (remaining 72 hours) drug response1. While exciting, this approach may not be practical. Most institutions may not have the resources to allocate two receivers for one patient over a 4 day period. We have presented our experience using a standard 48 hour, single receiver, Bravo pH capsule to measure esophageal acid exposure both off and on PPI therapy.
Methods: All Bravo pH studies performed at our institution between 12/04 and 4/06 were reviewed. Patients were instructed to withhold PPI for 7 days prior to the study. All Bravo capsules were placed the standard 6 cm above the squamocolumnar junction. During the first 24 hours, the patient remained off a PPI. The patient was then instructed to take either 40 mg of rabeprazole or 80 mg of esomeprazole by mouth. This dose was repeated 12 hours later. The percent of time that pH was less than 4 over 24 hours (% time pH<4) was the primary variable examined. Total number of refluxes over a 24 hour period was also considered. Day 1 vs. day 2 values were compared using the Wilcoxon signed-rank test.
Results: Fifty-four studies were reviewed. One study was removed as the capsule was radiologically shown to have detached and fallen into the gastric chamber during the study period. Three studies had a% time pH<4 nine standard deviations above the mean and were therefore excluded. The mean% time pH<4 was significantly lower on day 2 (2.68%) as compared to day 1 (5.49%) (p= 0.003). The total number of refluxes per 24 hours was also significantly reduced (34.4 vs. 54.2) (p= 0.004).
Conclusions: We have shown that it is feasible to evaluate esophageal acid exposure both off and on PPI therapy during a single 48 hour Bravo pH study. By giving a high dose of a rapid acting PPI on day 2, the esophageal acid exposure can be significantly reduced. This may be more practical than performing two separate studies or a single prolonged study using multiple receivers.
1. Hirano I, et al. Clin Gastroenterol Hepatol 2005; 3:1083–8