Impedance Analysis Using High-resolution Impedance Manometry Facilitates Assessment of Pharyngeal Residue in Patients With Oropharyngeal Dysphagia

Background/Aims Impedance analysis using high-resolution impedance manometry (HRIM) enables the recognition of pharyngeal residue in patients with oropharyngeal dysphagia. The aims of this study were to evaluate appropriate criteria for impedance analysis in a large patient cohort, as well as the diagnostic accuracy and agreement of analysis performed by HRIM trainees. Methods We reviewed 33 controls (13 males; median age, 61.2 years) and 104 oropharyngeal dysphagia patients (61 males; median age, 70.4 years) who underwent a flexible endoscopic evaluation of swallowing study (FEES) and HRIM. Two experts compared the pharyngeal residue on FEES and impedance color pattern at 1,000, 1,500 and 2,000 Omega of the impedance bar. Three trainees were given a 60 minutes tutorial to determine the diagnostic accuracy and agreement of this analysis. Results The diagnostic sensitivity of experts for predicting liquid residue was 73.1% for 1,000 Omega, 96.2% for 1,500 Omega and 100% for 2,000 Omega. Significantly higher sensitivity was observed at 1,500 Omega compared to 1,000 Omega (P < 0.001). The diagnostic specificity of experts for liquid residue was 98.3% for 1,000 Omega, 96.6% for 1,500 Omega and 83.1% for 2,000 Omega. There was a higher specificity at 1,500 Omega compared to 2,000 Omega (P = 0.008). The kappa value among the 3 trainees was 0.89 and the diagnostic accuracy of the trainees for liquid residue was comparable to that of the experts. Conclusions The impedance analysis at 1,500 Omega provides more accurate information for the detection of liquid residue, irrespective of the level of expertise.