Cristina Ogliari

Perceptual sensitivity and response bias during rectal distension in patients with irritable bowel syndrome.

Abstract  Patients with irritable bowel syndrome (IBS) report an increased frequency of sensations during rectal distension in comparison with healthy subjects. This alteration might be due to a psychological response bias leading patients to over report their sensations. The aim of this study was to measure perceptual sensitivity and response bias during rectal distension in healthy subjects and IBS patients using the sensory decision theory (SDT). Thirteen healthy subjects and 22 IBS patients underwent five rectal distensions up to 100 mL, five up to 200 mL and five sham distensions. They were asked to identify the distension by means of an electronic marker. Perceptual sensitivity and response bias were calculated according to the SDT. The patients identified a more 100 mL distensions than the healthy subjects (P = 0.02), whereas there was no difference in the number of identified 200 mL and sham distensions between the two groups. The perceptual sensitivity of IBS patients was significantly greater during 100 mL (P = 0.01), but not during 200 mL distensions. The response bias was not significantly different between the two groups. These data suggest that the increased frequency of sensations reported by IBS patients is not due to a psychological response bias.

Abdominal distension after colonic lactulose fermentation recorded by a new extensometer

Abstract Colonic lactulose fermentation induces bloating, but whether it also causes abdominal distension is not known. The aim of this study was to assess the effect of colonic lactulose fermentation on abdominal girth using a new extensometer. We recorded abdominal girth in 24 healthy subjects by means of an extensometer that measures the phase shift of an ultrasound wave propagating in a tube encircling the abdomen. The recordings were continuously made for 3 h after the ingestion of 100 mL of tap water with (16 subjects) or without (eight subjects) 10 g of lactulose. Every 10 min, H2 in the breath was analysed and the intensity of bloating was recorded. Bloating was never reported after water ingestion, whereas it was reported by 10 subjects after lactulose ingestion (P = 0.002). The mean ± SD changes in abdominal girth in comparison with resting conditions were statistically significant after lactulose ingestion (3 ± 2.9 mm; P = 0.002) but not after water ingestion (−0.2 ± 2.7 mm; P = 0.82). The area under the curve of the changes in abdominal girth after lactulose were significantly greater than after water ingestion (P = 0.03). In conclusion, colonic lactulose fermentation induces bloating and abdominal distension. The new extensometer is useful for continuously recording changes in abdominal girth.

Fecal Clostridiales distribution and short-chain fatty acids reflect bowel habits in irritable bowel syndrome: Fecal microbial ecosystem of IBS subtypes

Irritable bowel syndrome (IBS), a common functional gastrointestinal disorder, is classified according to bowel habits as IBS with constipation (IBS-C), with diarrhea (IBS-D), with alternating constipation and diarrhea (IBS-M), and unsubtyped (IBS-U). The mechanisms leading to the different IBS forms are mostly unknown. This study aims to evaluate whether specific fecal bacterial taxa and/or short-chain fatty acids (SCFAs) can be used to distinguish IBS subtypes and are relevant for explaining the clinical differences between IBS subcategories. We characterized five fecal samples collected at 4-weeks intervals from 40 IBS patients by 16S rRNA gene profiling and SCFA quantification. Finally, we investigated the potential correlations in IBS subtypes between the fecal microbial signatures and host physiological and clinical parameters. We found significant differences in the distribution of Clostridiales OTUs among IBS subtypes and reduced levels of SCFAs in IBS-C compared to IBS-U and IBS-D patients. Correlation analyses showed that the diverse representation of Clostridiales OTUs between IBS subtypes was associated with altered levels of SCFAs; furthermore, the same OTUs and SCFAs were associated with the fecal cytokine levels and stool consistency. Our results suggest that intestinal Clostridiales and SCFAs might serve as potential mechanistic biomarkers of IBS subtypes and represent therapeutic targets.

Effect of rectal distension on abdominal girth

Abstract  It has been postulated that a viscerosomatic reflex activated by gut distension and inhibiting abdominal wall muscle tone may be one of the mechanisms underlying functional abdominal distension. Any demonstration of such a reflex has to take into account the fact that gut distension may increase abdominal girth as a result of volume displacement. As biomechanical and sensory rectal responses vary at different rates of rectal distension, we hypothesized that different rates of rectal distension might reveal different changes in abdominal girth. Abdominal girth was continuously recorded in 14 healthy subjects using a previously validated extensometer. The rectal distensions were made in a randomized order at rates of 100 mL min−1 or 10 mL min−1 up to 150 mL, and sham distensions were used as controls. An increase in abdominal girth was observed at the end of both distensions (P ≤ 0.008): it was greater after the fast (1.1 ± 0.5 mm) than after the slow distension (0.8 ± 0.7 mm), but this difference was not statistically significant (P = 0.2). In conclusion, we were unable to demonstrate the existence of a viscerosomatic reflex activated by gut distension under our experimental conditions.

W1079 Effect of Endoscopic Fundoplication With EsophyX Device on Proton Pump Inhibitors Usage in a Single Third Level Italian Care Center

Background: Handicapped patients with advanced neurological impairment and dysphagia require gastrostomy feeding and are associated with gastroesophageal reflux disease (GERD). Concurrent fundoplication is often recommended at the time of gastrostomy placement (GP) in those patients because of avoiding long-term anti-reflux medication or preventing future reflux symptoms. Fundoplication has recently been thrown doubts about its indication in those patients because of unignorable complications and the high incidence of recurrence of GERD. It was aimed in this study to conduct a retrospective review of the outcome of handicapped patients with GP alone. Methods: The subjects consisted of 60 profoundly handicapped patients requiring tube feeding, aged 1 yr to 33 yrs (median 9 yrs), who underwent GP alone. The operative criteria included no or medically controllable reflux symptoms. Operative procedure was laparoscopic in 53 and open in 7. They were divided into two groups based on % esophageal total time pH<4.0 (reflux index:RI) evaluated with preoperative 24-hour esophageal pH monitoring; Group I (GI, n=37): RI<5.0 %, median age 7 yrs (2yrs-33 yrs), Group II (GII, n=23): RI≥5.0 %, median age 11yrs(1yr -21 yrs). Postoperative pH monitoring was performed in 26 GI patients and 20 GII. Follow-up period ranged 2 yrs to 8 yrs(median 4 yrs). Data are expressed as medians and ranges. Results: Postoperative medical management of GERD succeeded in 3 of 4 GI patients and 12 of 13 GII with lansoprazole, famotidine, and a herbal medicine, rikkunshito. A GI patient with chromosomal anomaly required fundoplication after GP because of intractable emesis. A GII with Cockayne Syndrome required gastrojejunal continuous feeding because of emesis and diarrhea. Other patients were successfully nourished with gastrostomy bolus feeding. Respiratory symptoms were ameliorated in a GI patient and 3 GII presumably due to the removal of stimulation by nasogastric tubes. Chronic gastric volvulus was corrected in 4. The postoperative RI increased significantly in GI patients (2.0% [0%-4.8%] vs. 4.1%[0.2%11.9%], P=0.002), whereas decreased significantly in GII (11.8% [5.9%-67.2%] vs. 9.7%[1.0%-68.7%], P=0.048). Conclusions: Reflux symptoms and pathological esophageal acid exposure rarely deteriorate after GP in profoundly handicapped patients with dysphagia. GP alone is a less invasive and effective procedure to improve the quality of life in those patients. Concomitant fundoplication is unnecessary in most of them with adequate medical control of reflux symptoms.