Responses to gastric gas in patients with functional gastrointestinal disorders

Background Gas-related abdominal symptoms are common in patients with functional gut disorders, but the responses to cope with the large volumes of gas that enter daily into the stomach have not been studied in detail. Our aim was to evaluate transit and tolerance of gastric gas in patients with functional gastrointestinal disorders. Methods In eight healthy volunteers and 24 patients with functional gut disorders (eight functional dyspepsia, eight belching disorder, and eight functional bloating) 1500 ml of a gas mixture were infused into the stomach at 25 ml/min. Belching, rectal gas evacuation, and abdominal perception were continuously recorded for 90 minutes. Key Results Healthy subjects expelled the infused gas per rectum (1614 +/- 73 ml), with a small rise in epigastric perception (score increment 1.0 +/- 0.4) and virtually no belching (1 +/- 1 belches). Patients with functional dyspepsia had a hypersensitive response to gastric gas, with a significant rise in epigastric perception (score increment 2.5 +/- 0.6;P = .045), a transient delay in rectal gas evacuation and similar belching as healthy controls. Patients with belching disorders responded to gastric gas with continuous belches (33 +/- 13 belches;P = .002), low epigastric perception, and a small reduction in rectal gas evacuation. Patients with functional bloating exhibited a slow transit response, with reduced rectal gas evacuation (1017 +/- 145 ml;P = .002) and abdominal symptoms (score increment 2.5 +/- 0.7), but without compensatory belching. Conclusions and Inferences Different pathophysiological mechanisms underlay specific adaptive responses to gastric gas in patients with different functional gut disorders. Therapeutic interventions for gas-related abdominal symptoms should be addressed towards these specific pathophysiological disturbances.