A New PH Catheter for Laryngopharyngeal Reflux: Normal Values

Objectives/hypothesis: Laryngopharyngeal reflux (LPR) represents a challenging field. Therapeutic studies of proton pump inhibitors in LPR have shown mixed results. The Restech pH catheter (Respiratory Technology Corp., San Diego, CA) is a minimally invasive device for detection of oropharyngeal acid reflux. The aim of this study was to provide normative data using this device in both distal esophagus and oropharynx.

Study Design: Prospective observational study.

Methods: Normal volunteers were recruited to undergo pH monitoring. A custom made longer catheter was used to assess distal esophageal pH. Oropharyngeal pH catheter was placed at the level of uvula. The distribution of % time was summarized using the 5th, 25th, 50th (median), 75th, and 95th quantiles for pH < 6, pH < 5, and pH < 4 for both upright and supine positions.

Results: A total of 20 normal, healthy volunteers underwent pH monitoring for 14 to 24 hours (median 20.5 hours). The 95th percentile for % total time pH < 4, pH < 5, pH < 6 for the distal esophageal pH catheter were 4.52%, 10.91%, and 42.99%, respectively. For the oropharynx pH probe, the 95th percentile for % total time pH < 4, pH < 5, and pH < 6 were 0.02%, 2.33%, and 21.41% respectively. The 95th percentile for number of reflux events for total pH < 4, pH < 5, and pH < 6 were 1.3, 8.1, and 128.0, respectively.

Conclusions: Oropharyngeal acid reflux is an infrequent occurrence in healthy volunteers without LPR. The normative data for Restech pH catheter may now be compared to those with suspected LPR.