Impaired transit and tolerance of intestinal gas in the irritable bowel syndrome

TLDR

Patients with irritable bowel syndrome frequently complain of excessive gas, yet fasting intestinal gas volumes appear normal. The study aimed to determine whether impaired intestinal gas transit and tolerance contribute to IBS symptoms by comparing IBS patients with healthy controls. Researchers infused a gas mixture into the jejunum of 20 IBS patients and 20 controls at 12 ml/min for four hours, recording flatus and intrarectal gas evacuation, symptom perception, and abdominal distension at 10‑minute intervals. IBS patients exhibited markedly higher gas retention, gastrointestinal symptoms, and abdominal distension after two hours of gas collection—18 of 20 patients versus four of 20 controls—and 13 of 17 still showed abnormal responses during intrarectal collection.

Abstract

Abstract <i>Background</i>—Patients with irritable bowel syndrome (IBS) frequently complain of excessive gas but their fasting volume of intestinal gas is apparently normal. We hypothesised that the pathophysiological mechanism involved may be impairment of intestinal gas transit. <i>Aim</i>—To investigate intestinal gas transit and tolerance in IBS patients compared with healthy subjects. <i>Methods</i>—A gas mixture (N₂, O₂, and CO₂ in venous proportions) was infused into the jejunum of 20 patients with IBS and 20 healthy controls at 12 ml/min for four hours. Gas evacuation, initially flatus from the anus (two hours) and then intrarectally (two hours), was continuously recorded. Symptom perception (0–6 scale) and abdominal distension were measured at 10 minute intervals. <i>Results</i>—After two hours of external gas (flatus) collection, 18 of 20 IBS patients had developed gas retention (&gt;400 ml), increased gastrointestinal symptoms (score &gt;3), or abdominal distension (&gt;3 mm girth increment) compared with only four of 20 control subjects. During intrarectal gas collection, 13 of 17 patients still exhibited abnormal responses. <i>Conclusion</i>—A large proportion of patients with IBS can be shown to have impaired transit and tolerance of intestinal gas loads. This anomaly may represent a possible mechanism of IBS symptoms, specifically pain and bloating.