Orocaecal transit time in health and disease

Appetite, the enteroendocrine system, gastrointestinal disease and obesity

The enteroendocrine system is located in the gastrointestinal (GI) tract, and makes up the largest endocrine system in the human body. Despite that, its roles and functions remain incompletely understood. Gut regulatory peptides are the main products of enteroendocrine cells, and play an integral role in the digestion and absorption of nutrients through their effect on intestinal secretions and gut motility. Several peptides, such as cholecystokinin, polypeptide YY and glucagon-like peptide-1, have traditionally been reported to suppress appetite following food intake, so-called satiety hormones. In this review, we propose that, in the healthy individual, this system to regulate appetite does not play a dominant role in normal food intake regulation, and that there is insufficient evidence to wholly link postprandial endogenous gut peptides with appetite-related behaviours. Instead, or additionally, top-down, hedonic drive and neurocognitive factors may have more of an impact on food intake. In GI disease however, supraphysiological levels of these hormones may have more of an impact on appetite regulation as well as contributing to other unpleasant abdominal symptoms, potentially as part of an innate response to injury. Further work is required to better understand the mechanisms involved in appetite control and unlock the therapeutic potential offered by the enteroendocrine system in GI disease and obesity.

Assessment of Small Intestinal Transit Times in Ulcerative Colitis and Crohn's Disease Patients with Different Disease Activity Using Video Capsule Endoscopy

Small intestinal transit times (SITT) influence drug bioavailability. This study aimed to compare SITT in Crohn's disease and ulcerative colitis patients with non-inflammatory bowel disease (IBD) and to determine influence of disease activity on transit times, and in addition, to establish the utility of small bowel video capsule endoscopy (SB-VCE) in investigation of SITT in IBD patients. A retrospective review was performed on consecutive patients who had undergone SB-VCE at a university hospital out-patient clinic. In total, 125 non-IBD patients, 55 Crohn's disease patients, and 23 ulcerative colitis patients were included. SITT were calculated from the first duodenal image to the first cecal image. Disease activity was assessed based on endoscopy results and inflammatory markers (calprotectin, C-reactive protein, erythrocyte sedimentation rate). SITT were longer in ulcerative colitis patients compared to non-IBD patients (median 264 min vs. 216 min, p = 0.010). Patients with active Crohn's disease (n = 33) also displayed prolonged SITT compared to non-IBD patients (median 253 min vs 216 min, p = 0.017) and patients with quiescent Crohn's disease (n = 22) (p = 0.005). SITT can be prolonged in IBD patients depending on disease activity which may alter the drug release profiles and clinical response to colonic drug delivery systems. SB-VCE is a simple, non-invasive tool that can be utilized in pharmacokinetic studies to understand drug bioavailability in different patient groups. Moreover, this variability in transit times needs to be simulated in dissolution testing for in vitro in vivo correlations.

Measurement of oro-caecal transit time by magnetic resonance imaging

OBJECTIVES

To assess prospectively the agreement of orocaecal transit time (OCTT) measurements by lactulose hydrogen breath test (LHBT) and magnetic resonance imaging (MRI) in healthy subjects.

METHODS

Volunteers underwent abdominal 1.5-T MRI using axial and coronal single-shot fast-spin-echo T2-weighted sequences, having fasted and after lactulose ingestion (10 g/125 mL). Imaging and H2 excretion gas-chromatography were performed concurrently every 15 min up to 180 min. MR images were analyzed using semiautomatic segmentation to calculate small bowel gas volume (SBGV) and visually to detect bolus arrival in the caecum. Agreement between MRI- and LHBT-OCTT was assessed.

RESULTS

Twenty-eight subjects (17 men/11 women; mean age ± standard deviation 30 ± 8 years) were evaluated. Two H2 non-producers on LHBT were excluded. OCTT measured by MRI and LHBT was concordant in 18/26 (69 %) subjects (excellent agreement, k = 0.924). Median SBGV was 49.0 mL (interquartile interval 44.1 - 51.6 mL). In 8/26 (31 %) subjects, MRI showed that the lactulose bolus was in the terminal ileum and not the caecum when H2E increased on LHBT. Median OCTT measured by MRI was significantly longer than OCTT measured by LHBT [135 min (120 - 150 min) vs. 127.5 min (105 - 150 min); p = 0.008]. Above baseline levels, correlation between [H2] and SBGV was significant (r = 0.964; p < 0.001).

CONCLUSIONS

MRI provides valid measurements of OCTT and gas production in the small bowel.

KEY POINTS

• MRI is a valid technique to measure OCTT. • Excellent agreement between MRI and LHBT was found. • Measuring gas production using MRI may provide evidence of small bowel fermentation.

A technique for safe placement of a biliary endoprosthesis after laparoscopic choledochotomy

BACKGROUND

Biliary endoprosthesis has been proposed as an alternative to T-tube placement after laparoscopic choledochotomy in an attempt to eliminate the complications associated with T-tubes. Biliary endoprostheses have been, until now, placed under fluoroscopic guidance. We present a modification of Gersin's method for endoprosthesis placement under direct vision.

PATIENTS AND METHODS

As of July 2001, seven patients who fulfilled the criteria for common bile duct (CBD) exploration through a choledochotomy, a biliary endoprosthesis was inserted under direct vision at the end of the procedure with primary closure of the CBD above it. In all cases, plastic biliary stents 10F in diameter were used ranging from 5 to 10 cm in length. We describe in detail the technique of CBD stent placement using the choledochoscope as the advancing device. We also propose the use of intraoperative cholangiography instead of on-table endoscopy to check the final correct position of the stent.

RESULTS

The median postoperative hospital stay was 2 days. Two patients developed transient hyperamylasemia in the immediate postoperative period. None of the patients developed short-term complications (<30 days), namely bile leak, CBD erosion, stent occlusion, or stent migration. The long-term results revealed early return to full daily activities and normal liver function tests. Stents were removed endoscopically 4 weeks after the initial procedure except in two patients who spontaneously passed them.

CONCLUSION

We propose a 10F 10-cm biliary endoprosthesis placed under direct vision as a safe, effective, time-sparing, and cost-effective adjunct to CBD exploration through a choledochotomy. Placement of the endoprosthesis is associated with low morbidity and eliminates the complications related to T-tubes.

Comparison of scintigraphy and lactulose breath hydrogen test for assessment of orocecal transit: lactulose accelerates small bowel transit

The lactulose breath test (LBT) and gastroenterocolonic scintigraphy (GECS) can both be used to measure orocecal transit time (OCTT). The aims of this study were (1) to measure OCTT by LBT and GECS and (2) to determine whether lactulose alters orocecal transit.

METHODS

Eight normal subjects underwent simultaneous breath hydrogen testing, GECS, and duodenal manometry while receiving either 10 g lactulose or placebo with a radiolabeled solid/liquid test meal during two studies. There was a good correlation between OCTT by LBT and GECS when performed simultaneously (r = 0.95; P < 0.001). OCTT by GECS with lactulose was significantly faster (P = 0.004) than by GECS without lactulose, despite no change in gastric emptying of liquids and slowing of gastric emptying of solids (P = 0.02). The postprandial duodenal motility index was greater with lactulose than with placebo (P = 0.031). This study demonstrates that LBT and GECS (without lactulose) are not equivalent measures of OCTT. The standard LBT accelerates OCTT and slows gastric emptying. Therefore, lactulose has a direct accelerating effect on small intestinal transit.

Abnormal progression of a liquid meal through the stomach and small intestine in patients with Chagas' disease

This study describes the abnormal pattern of gastrointestinal progression of a liquid meal in patients with the digestive form of chronic Chagas' disease. This condition is known as a natural model of intramural denervation of the gut. Sixteen patients with clinical and radiographic evidence of esophageal and/or colonic involvement and 18 healthy volunteers were studied. Orocecal transit time after the ingestion of a 10% lactulose solution (180 ml) tagged with 99mtechnetium was measured by a conventional H2 breath technique. Gastric emptying and the arrival of the front of the meal to regions of interest corresponding to proximal and distal areas of the small intestine were assessed by abdominal scintigraphy. Orocecal transit time was significantly greater (P < 0.05) in Chagas' disease patients (N = 13) than in control subjects (N = 18) (mean +/- SD: 100.7 +/- 48.7 min vs 62.9 +/- 18.2 min). Half-time for gastric emptying of liquids in chagasic patients (N = 9) was significantly lower (P < 0.01) than in controls (N = 7) (9.7 +/- 2.7 min vs 26.4 +/- 3.4 min). The time of arrival of the liquid meal to the proximal small intestine was also significantly shorter (P < 0.02) in patients than in controls (5.6 +/- 3.7 vs 11.4 +/- 5.5 min), but there was no difference between the two groups concerning the time the meal first arrived to the distal small intestine (15.0 +/- 11.0 min vs 23.5 +/- 11.4 min, P > 0.05). These results indicate that patients with Chagas' disease have a combination of exceedingly rapid gastric emptying and abnormally delayed transit of liquids through the more distal segments of the small bowel.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of a liquid diet with and without soluble fiber supplementation on intestinal transit and cholecystokinin release in volunteers

The effect of adding fiber to liquid formula diets on gastrointestinal transit is still controversial. Different fiber types (soluble vs insoluble) and different methodology of transit time measurements yielded variable results. Factors affecting transit include colonic fermentation, neural, and hormonal factors. We have therefore compared the effects of a standardized normal diet and two liquid formula diets with and without supplementation of a soluble fiber (21 g/L) on orocecal transit time measured by the hydrogen lactulose breath test, colonic transit time measured by radiopaque markers with an abdominal x-ray, bowel movements, stool consistency, and cholecystokinin release in 12 healthy male volunteers. The diets were consumed in a randomized order, each one for 7 days. The addition of soluble fiber did not affect orocecal transit time. Colonic transit time, however, was significantly prolonged (55 h) with fiber supplementation compared with the liquid diet (39 h) and the self-selected diet (30 h) (p < .01). Stool frequency and consistency was not significantly affected. During administration of both liquid diets, fasting cholecystokinin concentrations were significantly elevated compared with the concentrations found with a self-selected diet (p < .05). The fasting cholecystokinin concentration correlated significantly with the increase of segmental (right colon) colonic transit time (p = .02). The prolongation of colonic transit time in liquid diet-fed volunteers might be caused by the combined effect of increased colonic fermentation and high basal cholecystokinin concentrations.

Estimation of small bowel transit time following colectomy and ileal reservoir construction

A study was carried out to evaluate the breath hydrogen test as a method of estimating small bowel transit in patients with an ileal pouch and to determine whether gut transit time influenced functional outcome. Twelve patients with an ileal reservoir and ten control subjects ingested a test meal of 400 ml chicken soup, 20 g lactulose and 50 ml dilute barium solution. Concurrent breath hydrogen testing and radiological screening was carried out until the head of the test meal reached the ileal pouch or caecum. At the time that the test meal arrived in the pouch, faecal anaerobic bacterial counts were obtained. Pouch compliance, functional capacity and anal sphincter pressures were also measured. While there was an excellent correlation between radiological and breath hydrogen measures of orocaecal transit time in controls (P less than 0.001), no such relationship was found for oropouch transit. Four of the 12 patients with a pouch produced no hydrogen after test meal ingestion, while in two other such patients breath hydrogen peaks occurred when the head of the meal was in the jejunum. The magnitude of the breath hydrogen rise in patients with an ileal pouch correlated well with faecal anaerobic bacterial counts (P less than 0.01). The median (95 per cent confidence interval) radiological small bowel transit time was more rapid in patients with a pouch than in control subjects: 28 (23-33) versus 72 (46-86) min (P less than 0.01). Increased 24-h frequency of defaecation was associated with more rapid small bowel transit after ileal reservoir construction (P less than 0.01) but correlated with neither pouch capacity nor compliance. These data show that small bowel transit time may be a determinant of ileal pouch function but that breath hydrogen estimation of gut transit time in patients with an ileal reservoir is unreliable.

Role of fasting gastrointestinal motility in the variability of gastrointestinal transit time assessed by hydrogen breath test

Gastrointestinal motility and transit time, measured by the hydrogen breath test, were simultaneously assessed in six healthy volunteers. Each subject underwent six studies on separate days. On each day motility was measured in the gastric antrum, duodenum, and proximal jejunum and 15 g of lactulose was given either by mouth during gastric phases I, II, III of the motor migrating complex or infused duodenally during duodenal phases I, II, III, one phase being studied each day in random order. Fasting activity was not interrupted by the lactulose. The lactulose transit time decreased significantly from a peak with phase I through phase II to a minimum with phase III (mean (SD) 155 (26) min v 120 (10) min v 94 (14) min, p less than 0.001). Similar results were noted when the lactulose was instilled intraduodenally (156 (23) min v 125 (19) min v 100 (17) min, p less than 0.001). No correlation was found between motility index and transit. These results suggest that different phases of fasting gastrointestinal motility are major determinants of the transit time estimated by the hydrogen breath test and explain the variability of this test in practice.

The effects of dietary fibre on upper and lower gastro-intestinal transit times and faecal bulking

A total of 10 obese patients (body mass index greater than 25) undergoing treatment with a very low-calorie (330 kcal/day) liquid diet were treated without and with 10.5 or 21 g/day dietary fibre. Mean (+/- SE) faecal bulking increased significantly (P less than 0.001) in a dose-dependent manner from 314.8 +/- 54.4 g on a fibre-free diet to 517.2 +/- 45.4 g and 748.9 +/- 78.5 g, respectively, over 5 days on diets containing 10.5 and 21 g/day dietary fibre. Total mean colonic transit time decreased from 53.9 +/- 3.6 h on a fibre-free diet to 25.8 +/- 44 and 17.3 +/- 4.6 h, respectively, on diets including 10.5 and 21 g/day dietary fibre. Both right and left colonic transit times were similarly affected but no effect on orocaecal transit time was detected.