524 Toward Complete Identification of Patients With GERD; 96-Hour Wireless pH Monitoring Increases Reflux Detection Rate

Abstract

Introduction: Accurate and complete identification of patients with symptoms secondary to gastroesophageal reflux disease has been a clinical challenge. This has led to the classification, perhaps erroneously, of some patients as 48-hour wireless pH monitoring has been shown to increase the diagnostic yield of reflux detection. We hypothesize that 96-hour monitoring would further increase reflux detection rate. Methods: The study population consisted of 31 patients who underwent 96-hour wireless pHmonitoring between February 2012 and October 2013.Patients with incomplete studies due to capsule dislodgement or failed signal transmission, achalasia, previous antireflux or gastric bypass surgery were excluded. Patient demographics, presenting symptoms, manometric and pHmonitoring parameters were collected and compared. Patients were divided into pH negative, single day positive or multiple day positive groups for comparison. All studies were done off PPI medications for at least 7 days. A positive study was defined by DeMeester score >14.72 on any day. Results: Eighteen (58%) of the 31 patients were negative on all 4 days, 7 (23%) were positive on a single day and 6 (19%) were positive on multiple days. Thirteen percent of the patients (4/31) were only positive on day 3 or day 4 and would have been considered normal on a 48 hour study. Lower esophageal sphincter (LES) parameters correlated with the number of pH positive days including LES overall length ( σ=-0.43, p=0.02), IBP (σ=0.41, p=0.02) and IRP (σ=-0.54, p=0.003). Mean axial separation between the LES and CD, 0.16cm in pH negative, 0.66cm in patients with one day positive and 0.26 in patients with multiple days positive (p=0.1506). Conclusions: 96 hour wireless pH monitoring identified pathologic esophageal acid exposure in 13% of patients who would have been considered normal on 48 hour study. These patients are more likely to have less profound alteration in characteristics of the gastroesopahgeal barrier including LES length and axial crural diaphragm separation. Prolonged 96-hour pH monitoring may be necessary before classifying patients as GERD negative or functional heartburn.