Detecting nasopharyngeal reflux: a novel pH probe technique

Abstract

Objectives: We sought to ascertain the normal pH values in the aerosolized environment of the nasopharynx in healthy subjects and utilize a novel pH probe that allows measuring acidity in a nonliquid environment.

Methods: Between November 2009 and February 2011, healthy volunteers without a history of reflux or eustachian tube dysfunction were enrolled in the prospective study. A total of 20 subjects had a Dx-pH Measurement System Probe (Respiratory Technology Corp) placed near the torus tubarius. The pH probe records the pH throughout the 24-hour study. A pH below 5.5 while the subject was upright or below 5.0 while the subject was supine was used as a criterion to determine a reflux event. Recording was stopped during meals.

Results: For normal individuals with no history of reflux or eustachian tube dysfunction, the pH values obtained from the nasopharynx ranged from 6.10 to 7.92. The average pH was 7.03 (SD, 0.67). Eight subjects (40%) had at least 1 reflux event during the 24-hour pH study.

Conclusions: By utilizing a novel self-condensing pH probe, we were able to perform a 24-hour pH study in the nasopharynx of 20 healthy individuals. In our study, the average pH for individuals without symptomatic reflux or eustachian tube dysfunction was 7.03. Interestingly, 8 control subjects had at least 1 episode of pH below 5.5 while awake or below 5.0 while asleep, which was considered to be a reflux event in our study.