Brunworth J, Djalilian H, Garg R. AAO-HNSF Presentation, 2010.

OBJECTIVES: 1) Ascertain the normal pH values in the aerosolized environment of the nasopharynx in healthy subjects. 2) Utilize a novel pH probe which allows measuring acidity in a non-liquid environment.

RESULTS: For normal individuals with no history of reflux or eustachian tube dysfunction, pH values obtained from the nasopharynx ranged from 6.10 to 7.92. The average pH was 7.03 with a standard deviation of 0.69. Eight subjects (40%) had at least one reflux event during the 24-hour pH study. Decreases in pH were considered reflux events if the pH dropped below 5.5 while in the upright position or below 5.0 in the supine position. The average number of reflux events for subjects in the upright position was 0.6 events over a 24-hour period. In the supine position, the average number of reflux events was 0.5 over 24 hours. One patient was found to have 3 significant reflux events in the supine position, with the longest episode lasting 61.2 minutes.

CONCLUSION: Until recently it has been difficult to detect reflux in the upper airway because available pH catheters were developed to measure reflux in a liquid environment such as the esophagus. By utilizing a novel self-condensing pH probe, we were able to successfully perform a 24-hour pH study in the nasopharynx of 20 healthy individuals. It is our conclusion that the average pH for individuals without symptomatic reflux or Eustachian tube dysfunction is about 7.03. Interestingly, approximately 40% of healthy controls were found to have at least one episode of silent reflux.