FOUR-DIMENSIONAL IMPEDANCE MANOMETRY IN ESOPHAGEAL MOTILITY DISORDERS

Objectives: Four-dimensional high-resolution impedance manometry (4D HRM) uses impedance to estimate esophageal luminal cross-sectional area and track nadir impedance to measure intrabolus pressure (IBP). We aimed to determine whether 4D HRM metrics could define abnormal esophagogastric junction (EGJ) opening between Chicago Classification v4.0 (CCv4.0) motility disorders and compare 4D HRM with functional lumen imaging probe (FLIP) metrics. Methods: Symptomatic adult patients who completed high-resolution impedance manometry and FLIP were included and compared to an asymptomatic control group. 4D HRM analysis used custom-built software to measure IBP, maximum EGJ diameter and distensibility index (DI) on supine test swallows. 4D HRM metrics were compared to FLIP EGJ metrics. Results: Ninety patients (31 normal motility; 16 ineffective esophageal manometry; 9 absent contractility; 8 conclusive EGJ outflow obstruction (EGJOO); 12 type I achalasia; 14 type II achalasia; 12 type III achalasia and 34 asymptomatic controls) were included. Phase 2 and 3 IBP was higher in type II and III achalasia compared to controls and normal motility groups (p<0.03). Maximum EGJ diameter and EGJ-DI in the conclusive EGJOO and achalasia groups were significantly lower than in controls and normal motility groups (p<0.03). 4D HRM identified 37 out of 44 (84%) subjects with normal EGJ opening and 29 out of 39 (74%) subjects with reduced EGJ opening on FLIP. Conclusion: 4D HRM metrics correlated with expected clinical observations across a spectrum of esophageal motility disorders and defined EGJ obstruction. 4D HRM metrics may have value in defining EGJ obstruction in equivocal cases related to EGJOO or absent peristalsis.