The functional lumen imaging probe (FLIP) for evaluation of the esophagogastric junction

Abstract

P, Drewes AM, Gregersen H. The functional lumen imaging probe (FLIP) for evaluation of the esophagogastric junction. Am J Physiol Gastrointest Liver Physiol 292: G377-G384, 2007. First published August 31, 2006; doi:10.1152/ajpgi.00311.2006.-There is a need for new methods to study the dynamics of the esophagogastric junction (EGJ). The aims were to verify the efficacy and usefulness of a "functional lumen imaging probe" (FLIP) for the evaluation of the EGJ. Eight healthy volunteers (6 men), median age 26 (21-35) yr, and two achalasia patients underwent the FLIP procedure. The EGJ was located by manometry. The FLIP measured eight cross-sectional areas (CSAs) 4 mm apart together with the pressure inside a saline-filled cylindrical bag. The data showed the geometric profile of the EGJ reconstructed in a video animation of its dynamic activity. A plot of curve-fitted data for the smallest CSA vs. pressure after balloon distension indicated that the pressure increased from 18 cmH 2O at a CSA of 38 mm 2 to a pressure of 37 cmH2O at a CSA of 230 mm 2 for the healthy controls. In one achalasia patient (unsuccessfully treated with dilations), the CSA never rose above the minimal measurable value despite the pressure increasing to 50 cmH2O. In another achalasia patient (successfully treated with dilations), the pressure only reached 15 cmH2O despite opening to a CSA of 250 mm 2 . In conclusion, FLIP represents the first dynamic technique to profile the function and anatomy of the EGJ. The method can be used practically to evaluate difficult cases of EGJ dysfunction and may provide a role in evaluating patients before and after therapies for diseases affecting the EGJ such as achalasia and gastroesophageal reflux disease. esophagus; competence; distensibility; cross-sectional area; functional imaging THE LOWER ESOPHAGEAL SPHINCTER (LES) is not solely responsible for impeding the flow between the esophagus and the stomach. The crural diaphragm encircles ϳ2 cm of the esophagogastric junction (EGJ), and the sling or oblique fibers of the stomach also contribute to the mechanism (15, 21). Esophageal and gastric motility, pressures in the abdominal and thoracic cavities, and the exact location of the EGJ all play a role in defining its function. The anatomy and behavior of the EGJ also change with time and body posture (20). The EGJ is a very dynamic mechanical structure. A lot of knowledge about the anatomy of the EGJ has been assembled over the last 40 years, but much of our limited understanding of the behavior has been related to manometric studies. Intraluminal pressure recording is the current gold standard for determining the motility characteristics of the esophagus. Although manometry provides useful information on the location of the EGJ and on phasic motility within the lumens of the digestive tract, it may be more restrictive in what it can tell us about sphincteric regions and their dynamics.Two classic diseases involving the EGJ are gastroesophageal reflux disease (GERD) and achalasia. Achalasia is an esophageal ...

Current status of achalasia management: a review on diagnosis and treatment

“…Another diagnostic modality that can determine the dynamic profile of the esophagus is the functional lumen imaging probe (FLIP), used mostly at the esophagogastric junction [24]. This device consists of a distensible bag surrounding a catheter with impedance electrodes that measures cross-sectional area and impedance patterns [25].…”

Functional lumen imaging of the gastrointestinal tract

“…Variations in distensibility along the sphincter can be explained by the heterogeneous anatomy and active muscle function of the sphincters [39,54,56,57,69]. In addition to assessment of sphincter wall heterogeneity caused by changes in the mechanical properties and muscle tone, FLIP measurement is also capable of showing alterations caused by diseases, such as achalasia [47,68], systemic sclerosis [57], and idiopathic fecal incontinence [56]. These diseases are characterized by significant tissue reconstruction and remodeling, including increased collagen synthesis, dysmotility, and altered wall structure, which are all associated with the altered pressure-diameter relation [10].…”

“…Other groups led by Shaker, Mittal, and Pandolfino [11][12][13] independently developed other distension devices, but use of none of these has become common practice because of limitations caused by use of radiation, the degree of technical difficulty, and geometry-related factors. A major step forward in the development of impedance planimetry was made by Gregersen and coworkers [14] from 2004 and onward, where they developed several new designs of probes capable of making multiple geometric measurements and with improved electrode designs and signal conditioning for rectal studies and early FLIP studies by McMahon et al [15][16][17] on the esophagogastric junction (EGJ).…”

“…In recent years, several studies have also used the FLIP to characterize the functional properties of the esophagus and the EGJ. First, McMahon et al [15][16][17] showed the feasibility of the FLIP for evaluation of the EGJ. A few years later, Beaumont et al [32] examined Barrett's esophagus patients before and after radio-frequency ablation, and found the EGJ distensibility unchanged after the procedure.…”

“…Figure 7 shows a simple diagram of pressure versus stretch ratio for three locations in the anal sphincter. Studies done with the FLIP demonstrate the nonlinear pressure (tension)-deformation relationships of GI sphincters [33,54,57,68]. Often the pressure is observed to increase during the beginning of the measurement without much distension of the sphincter, but at some point, which may be termed the ''opening pressure,'' the sphincter starts to yield, after which it becomes much more compliant until a certain point.…”