Diagnosis of supra-esophageal gastric reflux: correlation of oropharyngeal pH with esophageal impedance monitoring for gastro-esophageal reflux.

BACKGROUND: Oropharyngeal (OP) pH monitoring has been developed as a new way to diagnose supra-esophageal gastric reflux (SEGR), but has not been well validated. Our aim was to determine the correlation between OP pH and gastro-esophageal reflux (GER) events detected by multichannel intraluminal impedance-pH (MII-pH).
METHODS: Fifteen patients (11 males, median age 10.8 years) with suspected GER were prospectively evaluated with ambulatory 24-h OP pH monitoring (positioned at the level of the uvula) and concomitant esophageal MII-pH monitoring. Potential OP events were identified by the conventional pH threshold of <4 and by the following alternative criteria: (i) relative pH drop >10% from 15-min baseline and (ii) absolute pH drop below thresholds of <5.5, 5.0, and 4.5. The 2-min window preceding each OP event was analyzed for correlation with an episode of GER detected by MII-pH. KEY
RESULTS: A total of 926 GER events were detected by MII-pH. Application of alternative pH criteria increased the identification of potential OP pH events; however, a higher proportion of OP events had no temporal correlation with GER (45-81%), compared with the conventional definition of pH < 4 (40%). A total of 306 full-column acid reflux episodes were detected by MII-pH, of which 10 (3.3%) were also identified by OP pH monitoring. CONCLUSIONS & INFERENCES: Use of extended pH criteria increased the detection of potential SEGR events, but the majority of decreases in OP pH were not temporally correlated with GER. Oropharyngeal pH monitoring without concurrent esophageal measurements may overestimate the presence of SEGR in children.