Introduction Although macroscopically normal, the oesophageal mucosa in patients with non-erosive reflux disease (NERD) displays epithelial dilated intercellular spaces (DIS). Such loss of barrier integrity is thought to be important in disease pathogenesis. Patients with NERD have DIS in both the distal and proximal oesophagus. Patients with functional heartburn (FH) do not have DIS. In healthy volunteers acid perfusion of the distal ooesophagus induces DIS not only in the exposed distal, but also the unexposed proximal oesophagus. It is unknown what impact distal acid perfusion has in the proximal oesophageal mucosa in symptomatic patients. Oesophageal impedance measurements can be an “in vivo” surrogate marker of functional mucosal integrity.

We aimed to assess with impedance the proximal oesophageal mucosal integrity during distal acid perfusion in symptomatic patients with NERD (+ve DIS) and FH (-ve DIS).

Methods We studied 22 patients (mean age 48, range 20–75) with typical reflux symptoms and negative endoscopy. 24-hour MII-pH monitoring identified 11 patients with NERD and 11 with FH. A pH-impedance catheter was inserted transnasally such that the proximal impedance segment was 15cm above the LOS. A 10 minute perfusion (10ml/min) of a neutral (pH7), then acidic (pH1) solution was performed in the distal oesophagus (10 cm from LOS) whilst simultaneously measuring proximal impedance. The absence of proximal fluid contamination was suggested by a lack of impedance drop during the neutral perfusion. Baseline impedance, and percentage change from baseline during the perfusion was calculated.

Results Distal perfusion of neutral solution caused no fall in proximal impedance (mean impedance 107 ± 2.8% of baseline). Distal perfusion of acidic solution caused a significant reduction in proximal impedance (mean impedance 80.3 ± 5.3% of baseline, p < 0.01). The drop of proximal impedance started at a mean of 175 seconds after commencement of acid perfusion. Proximal impedance did increase to a mean of 90% of baseline until 30 minutes after cessation of the acid perfusion. There was no significant difference in baseline proximal impedance (3165 ± 216Ω vs. 3116 ± 232Ω) or acid-induced change in proximal impedance (79.4 ± 8.1% vs. 81.2 ± 7.1% of baseline) between FH and NERD patients respectively.

Conclusion In keeping with morphological studies of healthy volunteers, distal oesophageal acidification modifies mucosal functional integrity of the proximal, unexposed oesophagus. This appears to occur regardless of the presence of pre-existing proximal DIS, suggesting that mechanisms of functional mucosal integrity as measured by impedance are beyond DIS formation.

Disclosure of Interest None Declared.