Objective: The mechanisms underlying symptoms in GERD, particularly in non-erosive reflux disease (NERD), remain to be fully elucidated. Weakly acidic reflux and presence of gas in the refluxate could be relevant in the pathogenesis of symptoms.
Design and Patients: To assess the relationship between symptoms and weakly acidic, acid and mixed (liquid + gas) reflux, 24-hour oesophageal pH-impedance monitoring was performed in 32 NERD and in 20 oesophagitis patients. In 12 NERD patients the study was repeated following 4-week PPI treatment. Impedance-pH data were compared with those of 10 asymptomatic controls. Heartburn and acid regurgitation were considered in the analysis of symptoms.
Results: 15 NERD patients showed a physiological acid exposure time (pH-negative). Weakly acidic reflux was significantly less frequent in patients (25±2%, m±SE) than in controls (54±4%, p<0.01). Gas was present in 45-55% of reflux events in patient groups and controls and decreased following PPI treatment. In NERD pH-negative patients, weakly acidic reflux accounted for 32±10% (vs 22±6% in NERD pH-positive and 12±8% in oesophagitis patients), mixed reflux for more than 2/3 of all symptom-related refluxes. Multivariate logistic analysis showed that in NERD pH-negative patients risk of reflux perception was significantly higher when gas was present in the refluxate (odds ratio: 3.2; 95% confidence intervals: 1.2-10; p<0.01).
Conclusions: The large majority of symptoms, in all patients, are related to acid reflux. In NERD patients, presence of gas in the refluxate significantly enhances probability of reflux perception. These patients are also more sensitive to less acidic reflux than oesophagitis patients.
- Gastro-oesophageal reflux disease
- Impedance-pH monitoring
- Non-erosive reflux disease
- Reflux perception