Tu1141 Esophageal Body Response to Volumetric Distension in Patients With Achalasia: A Study Utilizing the Functional Lumen Imaging Probe

Abstract

Background: Achalasia subtypes are differentiated by esophageal body pressurization patterns identified with esophageal pressure topography (EPT). The functional lumen imaging probe (FLIP), which measures cross-sectional area (CSA) as a function of pressure during volume distension, may enhance characterization of achalasia subtypes by detection of non-occlusive esophageal contractions not appreciated with standard manometric assessment. Our aim was to evaluate the esophageal body response to volumetric distention in achalasia patients using a new analysis paradigm, FLIP topography. Methods: Treatment-naive patients with achalasia defined and sub-classified by EPT were evaluated with the FLIP (Crospon, Inc, Gallway, Ireland) during endoscopy. The FLIP consisted of an infinitely compliant cylindrical bag with 17 ring impedance-planimetry electrodes spaced 1 cm apart and a solid-state transducer for simultaneous measurements of 16 channels of CSA and intra-bag pressure. The distal end of the FLIP was positioned across the esophagogastric junction to allow three intragastric channels. Stepwise bag distension from 5 to 60 mL was conducted and CSA and intrabag pressure data was exported to MATLABTM (The Math Works, Natick, MA). A customized MATLAB program generated FLIP topography plots (Figure) of CSA by axial position over time. Esophageal reactivity was identified by noting periods of reduced CSA as a surrogate for contractions. The intrabag pressure and distension volume at the onset of esophageal body contraction was measured and compared between achalasia subtypes using non-parametric tests. Results: 19 patients (ages 19-72; 6 female) with achalasia (2 type I, 11 type II, and 6 type III) were studied. Esophageal reactivity was observed in 0/2 type I, 6/11 (55%) type II, and 6/6 type III patients. Of patients that exhibited reactivity, numerically, but not statistically significantly, higher pressures at reactivity onset were seen in type II [median (IQR): 18.8mmHg (8.8-32.4)] than type III [10.2 (10-13.2), p =0.42] achalasia patients. The distension volumes at the onset of reactivity between subtypes were similar [type II: 27.5mL (25-30); type III: 27.5 (21.25-30); p =0.74]. Retrograde contractions were observed in 4/6 type II patients and 5/6 type III patients demonstrating reactivity. Conclusions: Assessment with FLIP topography detected variable reactivity to esophageal body distension between achalasia subtypes and among patients with type II achalasia. In approximately half of our studied type II achalasia patients, FLIP topography demonstrated some degree of preserved esophageal body contractility. Subclassification by esophageal body reactivity may help predict symptom development and/or response to treatment.