Impedance detected abnormal bolus transit in patients with normal esophageal manometry. Sensitive indicator of esophageal functional abnormality?

When used in combination with manometry, multichannel intraluminal impedance better characterizes the established manometric abnormalities into those with and without associated transit defects. However, the significance of the finding of normal manometry and abnormal impedance is not known. The objective of this study is to evaluate the clinical relevance of abnormal impedance associated with normal manometry during esophageal function testing in patients with a variety of esophageal symptoms. All patients referred for esophageal function testing during a 27-month period underwent combined multichannel intraluminal impedance and esophageal manometry studies including 10 liquid and 10 viscous swallows in supine position. From 576 patients with normal esophageal body manometry we identified 158 patients (27%) with abnormal impedance. The primary symptom in these 158 patients was compared to that in 146 consecutive patients with normal manometry and normal impedance selected from the original 576 patients. Abnormal bolus transit was found with viscous, liquid and both type swallows in 60%, 19% and 21% of the patients respectively. Of patients with abnormal bolus transit, 23% presented with dysphagia compared to 10% of normal transit patients (p = 0.0035). In conclusion, abnormal impedance even in patients with normal manometry may be a sensitive indicator of esophageal functional abnormality as represented by the symptom of dysphagia in these patients. Abnormal transit was more frequently identified with viscous than liquid swallows. Prospective studies to further clarify impedance detected transit defects in patients with normal manometry and the role of viscous swallows in diagnostic testing are warranted.