Use of Esophageal String Test to Understand Symptoms, Inflammation, and Function in Eosinophilic Esophagitis

When children are scheduled to undergo an endoscopy, research assistants will contact the family to arrange for the Esophageal String Test (EST) to be performed within one week of the endoscopy. The string test involves swallowing a small capsule with a thin piece of string inside it. The string unravels as the capsule goes down into the stomach. The investigator would tape the end of the string to the child's cheek, leaving it there for one hour. At the end of the hour, the investigator would remove the string by gently pulling it out through the mouth. Prior to swallowing the EST, the patient will complete the PEESS form (Pediatric Eosinophilic Esophagitis Symptom Scores) to assess symptoms.

The endoscopy and Endoscopic Reference System (EREFs) and EndoFLIP will be performed. The EndoFLIP is a slender probe covered by a smooth long balloon that is passed into the esophagus and slowly expanded with a salt solution. After standard of care endoscopic visualization, the FLIP, a 16 cm probe (Crospon) will be placed transorally and positioned 3 cm distal to the lower esophageal sphincter. Esophageal cross sectional areas and intrabag pressure will be measured during stepwise distensions beginning with 5 mL and increasing to a maximum of 70mL or intrabag pressure of 50 mmHg is achieved, whichever comes first. FLIP is FDA-approved without age restriction and its use has been approved by our IRBs previously. Primary results will be reported as distensibility plateau (mm).

Endoscopic severity: Endoscopic esophageal appearances will be scored using a validated EoE scoring system (EREFS). Five features of EoE will be scored: Edema (0-1), Rings (0-3) Exudates (0-2), Furrows (0-1), Stricture (0-1). Results will be reported as an inflammatory score (edema, exudates, furrows) and fibrostenotic score (rings, stricture). Functional Luminal Imaging Probe (FLIP):