[Comparative study on 24-hour multichannel intraluminal impedance-pH monitoring and Dx-pH monitoring in the diagnosis of laryngopharyngeal reflux].

Objective: The consistency and characteristics of 24-hour multichannel intraluminal impedance(MII)-pH monitoring and Dx-pH monitoring in the diagnosis of laryngopharyngeal reflux were investigated. Methods: Fifty-two patients with laryngopharyngeal reflux related symptoms or disease between March and October 2017 were included in this study.All patients were evaluated with 24-hour MII-pH monitoring and Dx-pH monitoring at the same time, recording each patient's number of positive laryngopharyngeal reflux events, time of acid clearance and Ryan index.The data was analysed with Mann-Whitney U test and consistency check. Results: Among all 52 patients, 16 patients(30.7%) had a positive MII-pH monitoring result and 14 patients(26.9%) had a positive Dx-pH monitoring results.The consistency of both technique for measurement of laryngopharyngeal reflux was general(κ=0.626). With MII-pH monitoring for reference, the sensitivity and specificity of 24-hour pH monitoring were 68.8% and 91.7%.A total of 62 positive reflux events(pH<4) were measured with MII-pH monitoring, and 50 positive reflux events(upright pH<5.5 or supine pH<5.0)were detected by Dx-pH monitoring.There were 44 positive reflux events detected by both techniques, the mean time of acid clearance was 22.8[13.5; 42.6] s. Correspondingly, 18 reflux events were measured by MII-pH monitoring without positive results of Dx-pH monitoring, the mean time of acid clearance was 5.2[3.5; 6.5] s. There was significant difference in the time of acid clearance between two groups( U =858.5, P <0.05). Conclusions: Dx-pH monitoring can accurately measure the change of pH value in airway, but exists the possibility of misdiagnosis especially when the time of acid clearance in laryngopharynx is short. MII-pH and Dx-pH monitoring can be complementary technique in the diagnosis of laryngopharyngeal reflux.