How Much Pharyngeal Exposure Is Normal? Normative Data for Laryngopharyngeal Reflux Events Using Hypopharyngeal Multichannel Intraluminal Impedance (HMII)

Laryngopharyngeal reflux (LPR) can cause atypical symptoms, asthma, and pulmonary fibrosis. The aim of this study was to establish the normative data for LPR using hypopharyngeal multichannel intraluminal impedance-pH (HMII). Asymptomatic subjects underwent endoscopy followed by 24-h HMII using a specialized impedance catheter configured to detect LPR before and after a 2-week course of proton pump inhibitors (PPI). Subjects were excluded if they had esophageal pathology or a positive DeMeester score. A cohort of 24 LPR patients who had a complete response to treatment was used for comparison with the normative data. Forty subjects were enrolled. Thirty-four subjects completed one, and 25 completed both HMII testing periods off and on PPI. There was no difference in the total number of reflux events between off and on PPI [22 (8-32) and 24 (10-28), respectively, p = 0.89]. The 95th percentiles of LPR off and on PPI were 0 and 1, respectively. All patients with treatment responsive LPR had pre-treatment HMII values of LPR greater than the 95th percentile. LPR events are rare in an asymptomatic population. One or more LPR events should be considered abnormal in patients with LPR symptoms regardless of whether there is a positive DeMeester score.