RESPONSE TO INTRALUMINAL GAS IN IRRITABLE-BOWEL-SYNDROME - MOTILITY VERSUS PERCEPTION

Our aim was to evaluate the response to intraluminal gas in irritable bowel syndrome and to determine whether this response was consequent u pon disordered motility or altered perception. We evaluated 10 patient s who satisfied the clinical criteria for the diagnosis of irritable b owel syndrome and 10 healthy controls. An eight-lumen perfused cathete r assembly was positioned to monitor motor activity in the duodenum an d proximal jejunum; a separate side port in the distal duodenum permit ted gas infusion. Subjects recorded symptoms of abdominal pain, bloati ng, and nausea throughout the study, using a visual analog scale. Foll owing an overnight fast and a 60-min basal recording period in the fas ted state, subjects ate a standard meal; 60 min later, ''sham'' gas wa s administered for 20 min, followed by the actual infusion of nitrogen gas at 40 ml/min. Subjects were randomized to receive atropine (7 mu g/kg) or placebo intravenously during the period of actual gas infusio n. Patients with irritable bowel syndrome described more pain (score, mean +/- SE, control versus irritable bowel: 0.22 +/- 0.16 vs 1.65 +/- 0.5, P < 0.01) and nausea (0.25 +/- 0.21 vs 1.45 +/- 0.64, P < 0.04) during sham gas; motility indices were similar in both groups. During active gas, irritable bowel syndrome patients reported more pain (0.40 +/- 0.39 vs 2.94 +/- 1.16, P < 0.03); motility indices at all sites w ere similar in both groups. Symptom severity in irritable bowel syndro me subjects randomized to receive atropine was similar to control subj ects during active gas infusion; motility indices were similar. We con clude that irritable bowel syndrome patients are more sensitive to int raluminal gas. This does not appear related to an exaggerated motor re sponse, but may reflect heightened central perception.