Role of colonic fermentation in the perception of colonic distention in irritable bowel syndrome and functional bloating.
ABSTRACT Bloating represents a frequent gastrointestinal symptom, but the pathophysiologic mechanism responsible for its onset is still largely unknown. Patients very frequently attribute the sensation of bloating to the presence of excessive bowel gas, but not all patients with gas-related symptoms exhibit increased intestinal production of gas. It is therefore possible that other still unrecognized mechanisms might contribute to its pathophysiology. Our aim was to evaluate whether a subgroup of patients affected by functional abdominal bloating presents hypersensitivity to colonic fermentation.
Sixty patients affected by functional gastrointestinal disorders (11 functional bloating, 36 constipation-predominant, and 13 diarrhea-predominant irritable bowel syndrome) and moderate to severe bloating took part in the study. Twenty sex- and age-matched healthy volunteers were enrolled as a control group. All the subjects underwent a preliminary evaluation of breath hydrogen excretion after oral lactulose. Then, on a separate day, an evaluation of sensitivity thresholds at rectal level was performed with a barostat before and after the induction of colonic fermentation with oral lactulose. A control test with electrolyte solution was also performed.
Both breath hydrogen excretion and mouth-to-cecum transit time did not differ between the 4 groups studied. Neither electrolyte solution nor lactulose modified sensitivity thresholds in healthy volunteers. In low hydrogen producers, basal perception and discomfort thresholds were similar to high hydrogen producers, but after lactulose both perception and discomfort thresholds were significantly reduced only in low hydrogen producers.
A subgroup of patients with functional gastrointestinal disorders and moderate to severe bloating might have hypersensitivity to products of colonic fermentation.
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ABSTRACT: The pathophysiology of bloating is largely unknown, and many mechanisms have been proposed. An alteration of intestinal gas production may have a role in a subgroup of patients, but available data are conflicting. We have previously shown that hypersensitivity to colonic fermentation is associated with severe bloating in a subgroup of patients with low intestinal gas production. Accordingly, we evaluated whether modification of intestinal gas production improves bloating severity according to the presence of visceral hypersensitivity to colonic fermentation. Twenty-four IBS-C patients with severe bloating underwent intestinal gas production measurement by hydrogen breath test after lactulose, and a recto-sigmoid barostat test in order to evaluate sensitivity thresholds in a basal condition and after induction of colonic fermentation. The subjects were then randomly assigned to receive either rifaximin or placebo according to a double-blind, randomized, cross-over trial. Rifaximin induced an improvement of symptom severity. A post hoc analysis according to the presence of hypersensitivity to colonic fermentation shows that rifaximin induces a significant improvement in symptom severity only in normosensitive, hyperproducer patients. Modulation of colonic flora, in order to reduce fermentation, does not interfere with bloating severity in patients with visceral hypersensitivity, thus suggesting that in this subgroup of subjects gas production is not crucial for the onset of bloating.Internal and Emergency Medicine 12/2010; 6(5):403-11. · 2.35 Impact Factor
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ABSTRACT: Irritable bowel syndrome (IBS) is a highly prevalent functional bowel disorder routinely encountered by healthcare providers. Although not life-threatening, this chronic disorder reduces patients' quality of life and imposes a significant economic burden to the healthcare system. IBS is no longer considered a diagnosis of exclusion that can only be made after performing a battery of expensive diagnostic tests. Rather, IBS should be confidently diagnosed in the clinic at the time of the first visit using the Rome III criteria and a careful history and physical examination. Treatment options for IBS have increased in number in the past decade and clinicians should not be limited to using only fiber supplements and smooth muscle relaxants. Although all patients with IBS have symptoms of abdominal pain and disordered defecation, treatment needs to be individualized and should focus on the predominant symptom. This paper will review therapeutic options for the treatment of IBS using a tailored approach based on the predominant symptom. Abdominal pain, bloating, constipation and diarrhea are the four main symptoms that can be addressed using a combination of dietary interventions and medications. Treatment options include probiotics, antibiotics, tricyclic antidepressants, selective serotonin reuptake inhibitors and agents that modulate chloride channels and serotonin. Each class of agent will be reviewed using the latest data from the literature.Therapeutic Advances in Gastroenterology 07/2009; 2(4):221-38.
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ABSTRACT: Irritable bowel syndrome patients with diarrhoea (IBS-D) often report intolerance to milk; however, the mechanism underlying these symptoms is unknown. To assess the role of psychological factors, immune activation and visceral sensitivity on the development of lactose intolerance (LI) in IBS-D patients. Fifty-five IBS-D patients and 18 healthy controls (HCs) with lactase deficiency underwent a 20-g lactose hydrogen breath test (LHBT). Patients were categorised as lactose malabsorption (LM; malabsorption only) or LI [malabsorption plus increase in total symptom score (TSS). Measurements included (i) psychological status; (ii) enteric biopsies with quantification of mast cells (MCs), T-lymphocytes and enterochromaffin cells; (iii) serum cytokines; (iv) rectal sensitivity before and after lactose ingestion. LI was more prevalent in IBS-D patients than HCs [25/55 (46%) vs. 3/18 (17%), P = 0.029]. IBS-D patients with LI had (i) higher levels of anxiety than those with LM (P = 0.017) or HCs (P = 0.006); (ii) increased mucosal MCs compared with LM (P = 0.006) and HCs (P < 0.001); (iii) raised serum TNF-α compared with LM (P = 0.034) and HCs (P < 0.001) and (iv) increased rectal sensitivity after lactose ingestion compared with LM (P < 0.001) or HCs (P < 0.001). Severity of abdominal symptoms after lactose ingestion was associated with the increase in visceral sensitivity after lactose intake (r = 0.629, P < 0.001), MCs (r = 0.650, P < 0.001) and anxiety (r = 0.519, P < 0.001). IBS-D patients with lactose intolerence are characterised by anxiety, mucosal immune activation and increased visceral sensitivity after lactose ingestion. The presence of these biomarkers may indicate an IBS phenotype that responds to dietary therapy and/or mast cell stabilisers (ClinicalTrials.gov Identifier: NCT01286597).Alimentary Pharmacology & Therapeutics 12/2013; · 4.55 Impact Factor