Hypopharyngeal pH monitoring artifact in detection of laryngopharyngeal reflux.

Hypopharyngeal pH artifacts have been a concern in the detection of laryngopharyngeal reflux. Our purpose was to analyze and quantify artifacts from dual-sensor hypopharyngeal pH monitoring. In all, 42 hypopharyngeal and 58 esophageal pH studies were reviewed. Type 1 (out of range), type 2 (pH drift), and type 3 (isolated pH drop) artifacts were identified. The proportion of proximal-sensor pH drop to <4 that was artifactual was determined. The median number (range) of artifacts was 1 (0-17) and 2 (0-28) for hypopharyngeal and esophageal pH studies, respectively (P = NS). The median proportion of artifactual pH drop to <4 was 1% (0-84%) and 2% (0-74%) for hypopharyngeal and esophageal pH studies, respectively (P = NS). The diagnosis did not change in any patient after excluding pH artifacts. In all, 19% of the combined 2,432 hypopharyngeal pH drops of <4 were artifacts. In conclusion, hypopharyngeal pH artifacts per study were uncommon but can be prominent in a few patients. One can identify these artifacts and exclude them from analysis.