Impaired reflex control of intestinal gas transit in patients with abdominal bloating

Background: Patients with abdominal bloating and distension exhibit impaired transit of intestinal gas which may lead to excessive gas retention and symptoms. Furthermore, we have previously shown that intestinal gas transit is normally accelerated by rectal distension. We hypothesise that in patients with functional bloating this modulatory mechanism fails and impairs gas transit. Methods: In 12 healthy subjects and eight patients with abdominal bloating we compared, by paired studies, the effect of rectal versus sham distension on intestinal gas transit. Gas was infused into the jejunum ( 12 ml/min) for three hours with simultaneous perfusion of lipids into the duodenum ( Intralipid 1 kcal/min) while measuring evacuation of gas per rectum. Results: In healthy subjects, duodenal lipid infusion produced gas retention ( 409 ( 68) ml) which was prevented by rectal distension (90 (90) ml; p< 0.05 v sham distension). In contrast, rectal distension in patients with abdominal bloating failed to reduce lipid induced gas retention ( 771 ( 217) ml retention during rectal distension v 730 ( 183) ml during sham distension; NS; p< 0.05 v healthy controls for both). Conclusion: Failure of distension related reflexes impairs intestinal gas propulsion and clearance in patients with abdominal bloating.