Relationship between baseline impedance levels and esophageal mucosal integrity in children with erosive and non-erosive reflux disease

Background  Baseline impedance measurement has been reported to be related to esophageal acid exposure and hypothesized to be a marker of microscopic changes of the esophageal mucosa. Aims of the study were to establish whether any relationship existed between the magnitude of intercellular space diameter (ISD) of esophageal mucosa and baseline impedance levels in children with gastro-esophageal reflux disease (GERD), and to compare baseline impedance levels between children with non erosive (NERD) and erosive (ERD) reflux disease. Methods  Fifteen children (median age: 11.2 years) with NERD, and 11 with ERD (median age: 9.6 years) were prospectively studied. All patients underwent upper endoscopy. Biopsies were taken 2-3 cm above the Z-line, and ISD was measured using transmission electron microscopy. All patients underwent impedance pH-monitoring, and baseline impedance levels were assessed in the most distal impedance channel. Key Results  Mean (±SD) ISD did not differ between NERD (1.0 ± 0.3 μm) and ERD (1.1 ± 0.3 μm, ns). Considering all patients together, no correlation was found between distal baseline impedance and ISD (r: -0.15; ns). Conversely, negative correlations were found between distal baseline impedance and acid exposure time (r: -0.76; P < 0.001), long-lasting reflux episodes (r: -0.78; P < 0.001), acid reflux episodes (r: -0.62; P < 0.001), and acid clearance time (r: -0.79; P < 0.001). Distal baseline impedance was significantly lower in ERD [1455 (947-2338) Ω] than in NERD children [3065 (2253-3771) Ω; P < 0.01]. Conclusions & Inferences  In children with GERD baseline impedance levels are not useful in predicting reflux-induced ultrastructural changes in the esophageal mucosa, despite their ability to discriminate between NERD and ERD.