Mechanical properties of the esophagus in eosinophilic esophagitis

Abstract

Background & aims: This study aimed to analyze the mechanical properties of the esophagus in eosinophilic esophagitis (EoE) using the functional luminal imaging probe (EndoFLIP; Crospon Medical Devices, Galway, Ireland).

Methods: Thirty-three EoE patients (22 male; age range, 23-67 years) and 15 controls (6 male; age range, 21-68 years) were included. Subjects were evaluated during endoscopy with the EndoFLIP probe, comprised of a compliant cylindrical bag (maximal diameter 25 mm) with 16 impedance planimetry segments. Stepwise bag distensions from 2 to 40 mL were conducted and the associated intrabag pressure and intraluminal geometry were analyzed.

Results: The EndoFLIP clearly displayed the tubular esophageal geometry and detected esophageal narrowing and localized strictures. Stepwise distension progressively opened the esophageal lumen until a distension plateau was reached such that the narrowest cross-sectional area (CSA) of the esophagus maximized despite further increases in intra-bag pressure. The esophageal distensibility (CSA vs pressure) was reduced in EoE patients (P = .02) with the distension plateau of EoE patients substantially lower than that of controls (median: CSA 267 mm(2) vs 438 mm(2); P < .01). Mucosal eosinophil count, age, sex, and current proton pump inhibitor treatment did not predict this limiting caliber of the esophagus (P ≥ 0.20).

Conclusions: Esophageal distensibility, defined by the change in the narrowest measurable CSA within the distal esophagus vs intraluminal pressure was significantly reduced in EoE patients compared with controls. Measuring esophageal distensibility may be an important adjunct to the management of EoE, as it is capable of providing an objective means to measure the outcomes of medical or dilation therapy.

Figure 1

Schematic of the EndoFLIP® distensibility protocol. See Materials and Methods for details.

Figure 2

Examples of EndoFLIP® distensions in a control subject (A), an EoE patient with a diffusely narrowed distal esophagus (B) and an EoE patient with a dominant distal esophageal stricture (C). In each panel on the left, esophageal distension is illustrated as a cylinder of varying diameter corresponding to the 16 cross-sectional areas (CSAs) measured by impedance planimetry within the EndoFLIP® bag along with the location of the narrowest CSA (indicated by the pink dot) and corresponding intra-bag pressure. The corresponding CSA vs. distension pressure graphs are to the right. Note that in the example of a control subject (A) the distension plateau is not reached unlike in the examples of EoE patients (B-C). This occurred in 20% of control subjects.

Figure 3

Esophageal distensibility (A & C) and compliance curves (B & D) in control subjects (blue) and EoE patients (red). Distensibility curves were computed from the fit to the one phase exponential association model defined by the distension plateau (Table 2) and κ. EoE patients exhibited diminished distensibility first evident in the 5-30 mm Hg pressure range and continuing for the remainder of the curves (P = .02). Esophageal compliance curves were significantly divergent, most evident at distension pressure 10 mmHg above which they seeming merge at 25 - 40 mm Hg (P = .02). There were no differences in either the distensibility or compliance curves between EoE patients subgrouped by PPI therapy at the time of evaluation (A & B) or the presence of a stricture in addition to rings ± furrows (C & D). Data shown as medians.