Introduction Patients with NERD have no erosions but impaired oesophageal mucosal integrity, that is, dilated intercellular spaces. It has been proposed that such microscopic changes can underlie symptoms in NERD, however, the relationship between impaired mucosal integrity and acid perception is unclear. Thus far, oesophageal mucosal integrity has been studied in vitro. Recently, oesophageal impedance basal values have been suggested as an in vivo surrogate to assess mucosal integrity in man. Low basal impedance is seen in patients with higher oesophageal acid exposure, and improves after PPI treatment. Oesophageal mucosal integrity, as expressed by basal impedance, is probably a dynamic process reflecting (1) the damaging effect of repeated acid reflux events and (2) the mucosal capacity to recover integrity. We hypothesised that there may be a relationship between mucosal integrity, recovery capacity and acid perception. We aimed to study the relationship between the dynamic properties of oesophageal mucosal integrity after acid challenge and symptom perception in patients with reflux symptoms.
Methods We studied 53 patients with typical reflux symptoms and no oesophagitis. A combined pH-MII catheter was inserted, and baseline distal oesophageal mucosal impedance measured for 15 min (and continuously thereafter). We performed a 10 min mid-oesophageal perfusion (10 ml/min) of a neutral solution. After a 10 min rest period an acid perfusion was performed with pH1 solution. Symptoms were recorded with a visual analogue scale. Impedance recovery was observed for 2 h post-acid perfusion in ambulatory conditions. Subjects then completed a 24 h reflux study.
Results There was significant inter-individual variability in pre-perfusion impedance baselines (mean 2059Ω, range 462–5388). Neutral perfusion caused a drop in impedance that recovered fully in 10 min. Acid perfusion caused a drop in impedance that was slow to recover. The mean impedance recovery rate was 7.5 Ω/min (25th–75th percentile=3.1–10.9). 32 of 53 patients perceived heartburn during acid perfusion. Patients with slower impedance recovery (<25th percentile, n=12) had lower basal impedance (mean±SEM 1331Ω±256 vs 3325Ω±325, p<0.01), higher 24 h acid exposure (5.2%±1.0 vs 1.7%±0.3, p<0.01), and more often acid sensitivity (10/12 vs 5/13, p<0.05) than those with faster impedance recovery (>75th percentile, n=13).
Conclusion A continuous impaired mucosal integrity (low impedance) might be a consequence of repeated reflux episodes with slow recovery. There is a link between mucosal integrity, recovery capacity and symptom perception. Low basal impedance and slow recovery after acid challenge are associated with increased acid sensitivity.
Competing interests None declared.