Background & aims: Although acid is likely to play a role in the genesis of symptoms in dyspeptic patients, most studies have failed to show an increase in gastric acid secretion. The aim of this study was to investigate clearance of acid from the duodenum and its relationship with symptoms in patients with functional dyspepsia.
Methods: Twelve patients and 10 healthy volunteers were studied using an assembly allowing recording of pressures and pH. Acid and saline were infused intraduodenally during phase II and postprandially. Sensations were scored before and 1 and 5 minutes after each infusion.
Results: After acid infusion in the fasting period, a greater increase in acidity in the duodenal bulb (P = 0.007) and fewer duodenal pressure waves (P = 0.002) were observed in dyspeptic patients. No significant differences in the time with pH < 4 and duodenal motor activity were observed in the postprandial period. Acid infusion reproducibly increased the sensation of nausea in patients (P < 0.001) but not in the controls. Saline infusion had no effect on upper gastrointestinal sensations.
Conclusions: In fasting dyspeptic patients, clearance of exogenous acid from the duodenal bulb and duodenal motor activity are decreased. The duodenal bulb in dyspeptic patients is hypersensitive to acid infusion, which induces the nausea.