LAUSR

c 2020 The Korean Society of Neurogastroenterology and Motility J Neurogastroenterol Motil, Vol. 26 No. 4 October, 2020 www.jnmjournal.org Ambulatory reflux monitoring assesses reflux burden using acid exposure time and reflux-symptom association. Chronic esophageal acid exposure in the animal and human models induces changes in the mucosa, seen histologically by increased numbers of dilated intracellular spaces. Low baseline impedance (BI) in the distal esophagus is likely explained by reflux-mediated damage to the integrity of esophageal mucosa. Esophageal BI has been suggested as a surrogate marker for esophageal mucosal integrity which may reflect longitudinal reflux mucosal injury over time. Distal esophageal mucosal BI measured during the ambulatory 24-hour esophageal pH-impedance monitoring is considered to be a surrogated market of reflux burden. Esophageal BI values can be acquired via several approaches; (1) from nocturnal periods without swallows during ambulatory pH-impedance tracings as mean nocturnal baseline impedance (MNBI), (2) from prototype balloon-mounted electrodes during sedated endoscopy (mucosal integrity or mucosal impedance [MI]), or (3) from high-resolution impedance manometry (HRIM) studies during the resting landmark phase prior to administration of test swallows (BI-HRIM). MNBI, BI-HRIM, and MI are all considered adjunctive metrics supporting a gastroesophageal reflux disease (GERD) diagnosis. MNBI may be of particular value when acid exposure time is inconclusive in predicting symptomatic outcomes with antireflux therapy. Both MNBI and BI-HRIM may be compromised by inconsistent or incomplete contact between impedance sensors and the esophageal mucosa due to the presence of intraluminal air or liquid bolus or a dilated esophagus. The recent study revealed that esophageal contractile segment impedance from HRIM correlates with MNBI and acid exposure time from 24-hour pH-impedance monitoring. BI-HRIM can distinguish patients with GERD from controls. Because HRIM catheters incorporate esophageal impedance sensors, BI-HRIM acquisition has the potential to provide complementary GERD diagnostic data with a shorter procedure time than JNM J Neurogastroenterol Motil, Vol. 26 No. 4 October, 2020 pISSN: 2093-0879 eISSN: 2093-0887 https://doi.org/10.5056/jnm20207 Editorial Journal of Neurogastroenterology and Motility