Published online Feb 21, 2017. doi: 10.3748/wjg.v23.i7.1289
Peer-review started: October 9, 2016
First decision: November 9, 2016
Revised: December 8, 2016
Accepted: December 21, 2016
Article in press: December 21, 2016
Published online: February 21, 2017
Processing time: 135 Days and 17.7 Hours
To assess reference values in the literature for esophageal distensibility and cross-sectional area in healthy and diseased subjects measured by the functional lumen imaging probe (FLIP).
Systematic search and review of articles in Medline and Embase pertaining to the use of FLIP in the esophagus was conducted in accordance with the PRISMA guidelines. Cross-sectional area and distensibility at the esophagogastric junction (EGJ) were abstracted for normal subjects, achalasia, and gastroesophageal reflux disease (GERD) patients, stratified by balloon length and volume of inflation.
Six achalasia studies (n = 154), 3 GERD (n = 52), and 5 studies including healthy controls (n = 98) were included in the systematic review. Normative data varied widely amongst studies of healthy volunteers. In contrast, studies in achalasia patients uniformly demonstrated low point estimates in distensibility ≤ 1.6 mm2/mmHg prior to treatment that increased to ≥ 3.4 mm2/mmHg following treatment at 40mL bag volume. In GERD patients, distensibility fell to the range of untreated achalasia (≤ 2.85 mm2/mmHg) following fundoplication.
FLIP may be a useful tool in assessment of treatment efficacy in achalasia. The drastic drop in EGJ distensibility after fundoplication suggests that FLIP measurements need to be interpreted in the context of esophageal body motility and highlights the importance of pre-operative screening for dysmotility. Future studies using standardized FLIP protocol and balloon size are needed.
Core tip: Functional lumen imaging probe (FLIP) uses impedance planimetry to calculate the distensibility of a hollow organ. In this systematic review, we aimed to assess FLIP reference values for gastroesophageal junction distensibility in healthy and diseased states. We found available normative data to vary widely. In achalasia, patients uniformly demonstrated low distensibility that improved after treatment, highlighting the role of FLIP in assessment of achalasia treatment efficacy. In gastroesophageal reflux disease, distensibility fell to the range of untreated achalasia following fundoplication, emphasizing the importance of pre-operative screening for esophageal body dysmotililty. Future studies using a standardized FLIP protocol and balloon size are needed.