Reproducible lactulose hydrogen breath test as a measure of mouth-to-cecum transit time

Testing for Chronic Diarrhea

Chronic diarrhea is a frequently encountered symptom in clinical practice. The etiologies for chronic diarrhea are diverse and broad with varying clinical implications. A useful method of categorizing chronic diarrhea to guide a diagnostic work-up is a pathophysiology-based framework. Chronic diarrhea may be categorized as malabsorptive, secretory, osmotic, and inflammatory or motility related. Frequently, overlap between categories may exist for any given diarrhea etiology and diagnostic testing must occur with an understanding of the differential diagnosis. Investigations to achieve a diagnosis for chronic diarrhea range from screening blood and stool tests to more directed testing such as diagnostic imaging, and endoscopic and histological evaluation. The pathophysiology-based framework proposed in this chapter will allow the clinician to select screening tests followed by targeted tests to minimize cost and complications to the patient, while providing a highly effective method to achieve an accurate diagnosis.

Poor predictive value of breath hydrogen response for probiotic effects in IBS

BACKGROUND AND AIMS

Previous observations suggested that an early rise in breath hydrogen after lactulose (ERBHAL) may identify patients with irritable bowel syndrome (IBS) likely to respond to probiotics. Therefore, we aimed to (i) investigate whether treatment with a probiotic changes breath hydrogen response in patients with ERBHAL and (ii) whether these changes identify patients who may benefit symptomatically from probiotics.

METHODS

In a randomized, double-blind, placebo-controlled trial, patients with IBS (Rome III) were randomized to either 65 mL/day fermented milk product containing probiotic (FMPP) or placebo for 6 weeks, followed by 6 weeks' open-label treatment and 6 weeks' withdrawal. Breath hydrogen responses to lactulose (15 g) and liquid-gastric emptying time were evaluated before and at the end of each treatment period. Symptoms were measured using a 100-mm visual analog scale.

RESULTS

Loss of ERBHAL occurred in 36% of 23 patients receiving FMPP and 41% of 22 receiving placebo (P = 1.00). Amongst 40 patients who completed open-label FMPP treatment, ERBHAL was lost in a further 38%, continued in 25%, and regained in 10%. Similar variability occurred in the withdrawal phase. Variability was unrelated to changes in gastric emptying. No differences in symptom response were seen between treatment groups nor in relation to the loss or retention of ERBHAL.

CONCLUSIONS

Breath hydrogen patterns after lactulose are poorly reproducible. No FMPP-specific effects on fermentation patterns or symptoms were observed. The presence of ERBHAL is not useful to predict symptomatic response to probiotic therapy in patients with IBS.

Semiquantitative assessment of breath hydrogen testing

BACKGROUND AND AIM

A major use of breath hydrogen testing is to assess absorptive capacity for sugars to assist dietary design for management of gut symptoms. Qualitative reporting takes no account of the vigor of hydrogen response and provides little insight into degrees of malabsorption. This study aimed to describe a semiquantitative reporting method and to compare results with those reported qualitatively.

METHODS

In consecutive Caucasian patients with Crohn's disease (n = 87), ulcerative colitis (59), functional gastrointestinal disorders (FGID) (162), and healthy controls (76), area under the curve was calculated for lactulose (15 g). This was compared with that for lactose (50 g) and fructose (35 g). Degree of malabsorption was categorized into arbitrary groups.

RESULTS

Semiquantitative results for ≥ 30% (designated "convincing") malabsorption was most similar to those using a qualitative cutoff value of 20 ppm, but in 38% and 21% of patients, the classification of malabsorption (nil or clinically significant) changed for fructose and lactose, respectively. Using a cutoff of 10 ppm, 49% and 5% were classified differently. Crohn's disease had a higher prevalence (42%) of convincing fructose malabsorption than controls (24%) or patients with FGID (33%) (P < 0.02). Highest prevalence of convincing lactose malabsorption (38%) was in ulcerative colitis, greater than controls (18%) and FGID (18%) (P < 0.02).

CONCLUSIONS

Semiquantitative assessment provides different results with different clinical implications in more than one third of patients, but disease-related alterations in prevalence are similar to those defined qualitatively. This method may be preferable because it lessens the confounding influence of the vigor of the hydrogen response.

Impaired gastric emptying and small bowel transit in children with mitochondrial disorders

OBJECTIVES

The primary aim of our study was to evaluate gastric emptying (GE) and intestinal transit time (ITT) in children with mitochondrial disorders (MD), and secondarily to evaluate the effect of prokinetics in those with prolonged GE.

METHODS

We enrolled subjects 3 to 18 years with MD and having any of the following gastrointestinal (GI) symptoms: abdominal pain, vomiting, constipation, diarrhea, or gastroesophageal reflux. Abdominal pain was scored by visual analog pain scale (1-10). Age-appropriate diet was labeled with radioactive technetium-99 sulfur colloid and its movement tracked along the GI tract. Delayed GE based on our institutional standards was defined as half emptying time >90 minutes for a solid and >60 minutes for a semisolid meal. Prolonged ITT was defined as >4 hours for the tracer to pass from mouth to cecum. A prokinetic was instituted to those with delayed GE, and the study was repeated if possible in 4 to 8 weeks.

RESULTS

Of the 26 subjects, 18 (69%) had delayed GE (median GE 99 minutes) and 12 (46%) had prolonged ITT. The study was repeated in 9 subjects after administering a prokinetic for >1 month. GE normalized in only 3 subjects (median GE on treatment 128 minutes). Mean abdominal pain score, which was 4.8 (max 10) in the 9 subjects, did not improve (5.6 after prokinetic therapy).

CONCLUSIONS

A high prevalence of delayed GE and prolonged ITT was seen in children with MD having GI symptoms, and these abnormalities were poorly responsive to prokinetic therapy.

Beverage consumption, appetite, and energy intake: what did you expect?

BACKGROUND

Beverage consumption is implicated in the overweight/obesity epidemic through the weaker energy compensation response it elicits compared with solid food forms. However, plausible mechanisms are not documented.

OBJECTIVE

This study assessed the cognitive and sensory contributions of differential postingestive responses to energy- and macronutrient-matched liquid (in beverage form) and solid food forms and identifies physiologic processes that may account for them.

DESIGN

Fifty-two healthy adults [mean ± SD age: 24.7 ± 5.5 y; BMI (in kg/m(2)): 26.3 ± 6.3] completed this randomized, 4-arm crossover study. Participants consumed oral liquid and solid preloads that they perceived, through cognitive manipulation, to be liquid or solid in their stomach (ie, oral liquid/perceived gastric liquid, oral liquid/perceived gastric solid, oral solid/perceived gastric liquid, or oral solid/perceived gastric solid). However, all preloads were designed to present a liquid gastric challenge. Appetite, gastric-emptying and orocecal transit times, and selected endocrine responses were monitored for the following 4 h; total energy intake was also recorded.

RESULTS

Oral-liquid and perceived gastric-liquid preloads elicited greater postprandial hunger and lower fullness sensations, more rapid gastric-emptying and orocecal transit times, attenuated insulin and glucagon-like peptide 1 release, and lower ghrelin suppression than did responses after oral-solid and perceived gastric-solid treatments (all P < 0.05). Faster gastric-emptying times were significantly associated with greater energy intake after consumption of perceived gastric-liquid preloads (P < 0.05). Energy intake was greater on days when perceived gastric-liquid preloads were consumed than when perceived gastric solids were consumed (2311 ± 95 compared with 1897 ± 72 kcal, P = 0.007).

CONCLUSIONS

These data document sensory and cognitive effects of food form on ingestive behavior and identify physical and endocrine variables that may account for the low satiety value of beverages. They are consistent with findings that clear, energy-yielding beverages pose a particular risk for positive energy balance. This study was registered at clinicaltrials.gov as NCT01070199.

Gastric emptying and orocaecal transit time of meals containing lactulose or inulin in men

The H(2) breath test is ideal for orocaecal transit time (OCTT) measurement, as it is non-invasive and inexpensive. Indigestible substrates added to a test meal are metabolised by the colonic bacteria, resulting in the production of H(2) which is detected in end-exhalation breath. However, the substrates themselves can alter the transit times in the gastrointestinal tract. The aim of the present study is to compare OCTT and gastric emptying (GE) when lactulose in liquid (L-L), solid lactulose (L-S) and solid inulin (IN-S) are added to a test meal, and subsequently, to examine if inulin alters GE. Firstly, ten male volunteers were tested on three occasions. Volunteers ate a pancake breakfast containing 100 mg of (13)C-octanoic acid and either 12 g of L-L, 12 g of L-S or 12 g of IN-S in a randomised order. Secondly, seven male volunteers were tested twice with meals containing either 12 g of IN-S or no substrate (NO-S). L-L induced the shortest OCTT (85.3 (sd 42.8) min) compared with L-S (162.4 (sd 62.6) min) and inulin (292.4 (sd 66.7) min; P = 0.007). GE half-time and lag phase (L-L: 61 (sd 9); L-S: 57 (sd 10); IN-S: 52 (sd 10) min; P = 0.005) were also affected, with L-L being the slowest. Thirdly, inulin reduced GE lag and latency phases (P < 0.05) compared with NO-S. Lactulose accelerates OCTT but delays GE compared with inulin. Inulin accelerates the onset of stomach emptying, but it has no effect on GE half-time. For these reasons, inulin is the preferred substrate for the H(2) breath test.

Investigation of autonomic function and orocecal transit time in patients with nonalcoholic cirrhosis and the potential influence of these factors on disease outcome

BACKGROUND

The presence of autonomic dysfunction in nonalcoholic cirrhosis and its influence on intestinal transit and disease outcome still need clarification.

GOALS

To investigate the function of the autonomic nervous system in patients with nonalcoholic cirrhosis and the possible associations among autonomic dysfunction, severity of liver disease, disturbed intestinal transit, and the development of complications during follow-up.

STUDY

Measurements of heart rate variability obtained by analysis of 24-hour ambulatory electrocardiographic recordings to assess autonomic function and lactulose breath hydrogen test to determine orocecal transit time were performed in 32 patients with nonalcoholic cirrhosis divided into Child A and B.

RESULTS

Child B patients showed significantly lower values (P<0.05) of those parameters reflecting parasympathetic (high frequency, log-transformed high frequency, pNN50) and sympathetic function (low frequency, log-transformed low frequency) in comparison with controls and Child A patients. Orocecal transit time values were significantly (P=0.02) higher in Child B patients than in controls, but no relationship was found between delayed orocecal transit time and autonomic dysfunction. During follow-up, 42% of Child B patients developed encephalopathy. This complication was significantly associated with autonomic dysfunction. In addition, in the 4 patients who died the parameters reflecting parasympathetic function were significantly reduced in comparison with those of survivors.

CONCLUSIONS

Autonomic dysfunction and delayed intestinal transit are related to the severity of disease in nonalcoholic cirrhosis. Autonomic dysfunction seems to predispose cirrhotic patients to the development of encephalopathy and may be associated with a poor prognosis of these patients.

Autonomic neuropathy may be associated with delayed orocaecal transit time in patients with cirrhosis

Orocaecal transit (OCT) time is delayed in patients with cirrhosis, but the reasons for this remain unclear. We hypothesized that autonomic neuropathy (AN) may explain the delay in OCT.

METHODS

We determined OCT and autonomic function tests (AFT) in 48 patients (Child A-15, B-27, C-6) with cirrhosis of various aetiologies. AFT were categorized as normal, borderline, or abnormal. OCT was measured using the lactulose hydrogen (H2) breath test. OCT was defined as the time from baseline when there was a rise in H2 levels of >20 ppm over baseline or >10 ppm over baseline sustained over 2 consecutive time points.

RESULTS

Based on OCT, patients were separated into those with delayed OCT (>90 min, group I) and normal OCT (< or = 90 min, group II). Mean OCT time of patients in group I was 169.7+/-49.7 min vs. 84.4+/-12.1 min in group II. Baseline clinical characteristics of patients with and without AN, and those with normal and delayed OCT were similar. Presence of mild encephalopathy did not have an effect on OCT. AN was seen more frequently in group I than group II [16/32 (50%) vs. 3/16 (19%), p=0.03]. Logistic regression analysis showed that the presence of AN was the only independent variable associated with delayed OCT (OR 7.3, CI 1.3-39.4, p=0.02).

CONCLUSION

Our study showed that the presence of AN was associated with delayed OCT in patients with cirrhosis.

Measurement of gastrointestinal transit

An abnormality in transit is commonly considered to account for unexplained gastrointestinal (GI) symptoms. Since the symptoms of delayed transit overlap with those of accelerated transit, direct measurement of GI transit is needed to establish an accurate diagnosis. Similarly, since symptoms originating from one part of the gut may overlap with symptoms from another, localizing transit abnormality to one organ vs. another using direct measurement is an important part of diagnostic evaluations. Consequently, noninvasive tests of GI transit should be done early in the evaluation to guide therapy. We now have tools to measure transit accurately; results of transit tests often depend on the conditions selected for the test, so test results will match clinical expectations most closely when test conditions are selected to reproduce the circumstances for symptom production. This review describes the most commonly used methods for the measurement of GI transit including the gastric emptying test for some dyspeptic symptoms, small bowel transit test for dyspeptic symptoms and diarrhea, colonic transit test for constipation, and factors that influence the result of these studies. As we make progress in our understanding of the pathophysiology of transit disorders, the clinical usefulness of these diagnostic tests will be further enhanced.

Evaluation of a triple sugar test of colonic permeability in humans

AIM

Conventional dual sugar tests of intestinal permeability assess only the stomach and small intestine. A novel triple sugar method of assessing colonic permeability has recently been described in animals. This utilizes the non-fermented sweetener sucralose, in addition to conventional sugars. It has been postulated that this test enables the simultaneous assessment of small-intestinal and colonic barrier function in humans. The aim of this study was to evaluate the triple sugar test using healthy volunteers and ileostomists.

METHODS

Twenty-one healthy volunteers and 18 ileostomists underwent the triple sugar test. After an overnight fast, subjects drank a solution containing lactulose (5 g), rhamnose (1 g) and sucralose (5 g). Urine was collected for 0-5 h and 5-19 h. Urinary sugars were quantified using HPLC, and 5 and 24-h excretion calculated. Nineteen control subjects and 16 ileostomists also underwent a 51Cr-EDTA permeability test. Permeability data were presented as medians (IQR), and differences between groups analysed with Mann-Whitney U-tests.

RESULTS

Lactulose excretion and the 5-h lactulose/rhamnose (L/R) ratio were similar in controls and ileostomists [L/R ratio 0.024 (0.022-0.034) vs. 0.025 (0.022-0.035), P = 0.955]. Twenty-four hours excretion of sucralose was significantly higher in control subjects compared with ileostomists [1.41% (1.17-1.68) vs. 0.96% (0.64-1.2), P = 0.003]. The same pattern was seen with 51Cr-EDTA [2.73% (2.06-3.76) vs. 2.06% (1.55-2.71), P = 0.037] and with lactulose [0.52% (0.42-0.60) vs. 0.25% (0.16-0.35), P = 0.002].

CONCLUSIONS

Both sucralose and 51Cr-EDTA underwent significant colonic absorption. A significant amount of lactulose also appeared to be absorbed in the colon. This unexpected finding requires further study.

Inulin is an ideal substrate for a hydrogen breath test to measure the orocaecal transit time

BACKGROUND

A better substrate is needed for a hydrogen breath test to measure the orocaecal transit time. The currently used substrate, lactulose, accelerates the orocaecal transit time by increasing the osmolality of the gut contents. The recently developed lactose 13C-ureide breath test is reliable, but a hydrogen breath test is preferred, as it allows the simultaneous investigation of the digestion and absorption of nutrients by means of 13C-labelled compounds.

METHODS

The usefulness of different types of inulin as a substrate for a hydrogen breath test was studied. Raftilin HP (>99% inulin with a degree of polymerization of between 5 and 60 and <0.5% glucose, fructose and sucrose) was further evaluated and compared with lactulose with regard to its effects on gastric emptying and the digestion of protein and lipids.

RESULTS

A good correlation was found between the orocaecal transit times using Raftilin HP (338 min; interquartile range, 300-383 min) and lactose 13C-ureide (353 min; interquartile range, 285-375 min) (r=0.85; P<0.001). The administration of 5 or 10 g Raftilin HP had no influence on the orocaecal transit time, whereas lactulose significantly shortened the orocaecal transit time. Neither inulin nor lactulose had a significant influence on gastric emptying or protein or lipid assimilation.

CONCLUSION

Raftilin HP is an ideal substrate for a hydrogen breath test to measure the orocaecal transit time.

Orocecal transit time in patients with functional dyspepsia

BACKGROUND

The importance of intestinal dysmotility in functional dyspepsia is a controversial issue.

GOALS

To investigate the orocecal transit time in patients with functional dyspepsia, as well as a possible association between intestinal transit and the presence of anxiety or Helicobacter pylori infection in these patients.

STUDY

The participants in this study were 23 patients with dysmotility-like functional dyspepsia and 24 control subjects. Orocecal transit time was measured by the lactulose hydrogen breath test. The presence of anxiety was assessed by the Hospital Anxiety and Depression (HAD) scale.

RESULTS

No significant difference in orocecal transit times was found between patients (median, 55 minutes; 95% confidence interval [CI], 40-60 minutes) and control subjects (median, 50 minutes; 95% CI, 40-60 minutes; p = 1). In the assessment, 15 patients (73%) scored for anxiety on the HAD scale, and 15 patients (65%) had positive test results for H. pylori. There was no significant difference in orocecal transit times between the patients with (median, 55 minutes; 95% CI, 40-63 minutes) and those without H. pylori infection (50 minutes; 95% CI, 40-68 minutes; p = 0.85), or between the patients with (median, 45 minutes; 95% CI, 40-68 minutes) and those without (60 minutes; 95% CI, 40-63 minutes; p = 0.77) anxiety.

CONCLUSIONS

Orocecal transit time is within the normal range in patients with functional dyspepsia. Anxiety and H. pylori infection do not seem to influence orocecal transit time in these patients.

Mouth to pouch transit after restorative proctocolectomy: hydrogen breath analysis correlates with scintigraphy

OBJECTIVES

Fast intestinal transit may be responsible for slow adaptation and unacceptable steady-state function after restorative proctocolectomy. Investigation of GI transit time may be valuable in such a setting. We hypothesized that postprandial hydrogen breath tests may yield transit data that correlate with technetium-labeled meal scintigrams.

METHODS

This study compared intestinal transit after a lactulose and bean meal via the breath hydrogen and scintigraphy methods in 21 ileoanal pouch subjects. The meal consisted of baked beans (425 g), 30 ml (20 g) lactulose syrup, 1 mCi 99mtechnetium sulfur colloid in finely chopped liver and 170 ml tap water. The meal contained 120 Kcal (70% carbohydrate, 18% protein and 12% fat).

RESULTS

Of 21 pouch subjects, 11 (53%) had breath tests and scintigraphy transit studies that differed by 5-21 min. Three of 21 (14%) scintigraphy mouth to pouch transit times were faster than breath test transits by 43-107 min. Seven of 21 (33%) subjects did not have breath test peaks >10 ppm. Mouth to pouch transit for breath hydrogen (104+/-16 min) and scintigraphy (98+/-7 min) tests had significant correlation (r = 0.96, p < 0.0001) among subjects with alveolar hydrogen peaks and accurate scintigrams (n = 11). Scintigrams were five times more expensive than breath tests.

CONCLUSIONS

A peaking hydrogen breath test provides an alternative to scintigraphy for estimating intestinal transit after ileoanal pouch.

No inhibition of gastro-intestinal propulsion after propofol- or propofol/ketamine-N2O/O2 anaesthesia. A comparison of gastro-caecal transit after isoflurane anaesthesia

BACKGROUND

Gastrointestinal motility may be considerably reduced by anaesthesia and or surgery resulting in postoperative ileus. Inhibition of propulsive gut motility is especially marked after an opioid-based technique. Little, however, is known of the gastrointestinal effects of the hypnotic propofol when given continuously over a longer period of time, which is the case in total intravenous anaesthesia (TIVA) and in intensive care sedation. We therefore set out to study the effects of a propofol-based nitrous oxide/oxygen anaesthesia (group PO) on gastro-caecal transit time. The results were compared with a propofol-ketamine technique (group PK) and an isoflurane-based anaesthesia (group I; each group n = 20).

METHODS

Gastro-caecal transit was determined by measurement of endexpiratory hydrogen concentration (ppm). Following gastral installation of lactulose at the end of the operation, the disaccharide was degraded by bacteria in the caecum, resulting in the liberation of hydrogen which was expired. A 100% increase in endexpiratory hydrogen concentration compared to the preinduction period was considered the end-point of gastro-caecal transit.

RESULTS

There was no significant difference with regard to gastro-caecal transit in the three groups of patients. In the propofol group mean gastro-caecal transit was 119 (+/- 50.6 SD) min, in the propofol-ketamine group it was 147 (+/- 57.4 SD) min, and in the isoflurane group transit time was 122 (+/- 48.6 SD) min.

CONCLUSION

The data suggest that propofol, even when given as a continuous infusion, does not alter gastrointestinal tract motility more than a standard isoflurane anaesthesia. The data may be particularly relevant to patients who are likely to develop postoperative ileus. They also suggest that in an ICU setting propofol does not alter gut motility more than a sedation technique with the analgesic ketamine.

Ileoanal pouch function and release of peptide YY

PURPOSE

This study evaluates peptide tyrosine-tyrosine (PYY), intestinal transit, fecal retention time, and anal sphincter manometry in colectomized patients with ileal pouch-anal anastomosis.

METHODS

Plasma and pouch PYY, mouth-to-pouch transit time, fecal retention time, and anal canal pressures were studied in 27 patients with ileoanal pouches a mean of 50 (range, 3-84) months after loop ileostomy closure.

RESULTS

Basal and peak postprandial plasma PYY were significantly reduced in patients with pouches compared with controls (P < 0.0001). Pouch PYY was decreased compared with control ileal PYY (P = 0.0003). No significant correlation was noted between intestinal transit and total integrated PYY response in patients with pouches (r=0.36; P=0.06). Fecal retention time was related to postprandial total integrated response of plasma PYY (r=0.43; P=0.02), mouth-to-pouch transit (r=0.87; P < 0.0001), and resting (r=0.44; P=0.02) and squeeze (r=0.62; P=0.0006) anal sphincter pressures.

CONCLUSIONS

Colectomized ileoanal patients with pouches showed decreased plasma and pouch PYY compared with controls. Intestinal transit was not significantly related to PYY release. However, prolonged pouch fecal retention was associated with greater PYY release, mouth-to-pouch transit, and anal sphincter pressures.

Bacterial overgrowth, intestinal transit, and nutrition after total gastrectomy. Comparison of a jejunal pouch with Roux-en-Y reconstruction in a prospective random study

BACKGROUND

Jejunal pouches after total gastrectomy have been introduced to diminish postgastrectomy symptoms and improve nutrition. However, the effect of a pouch on the intestinal bacteriology and transit is controversial.

METHODS

Bacterial overgrowth was measured with the glucose breath test and the mouth-to-caecum transit time (MCT) by means of the lactulose breath test after total gastrectomy and Roux-en-Y reconstruction in 24 patients with a pouch (Pouch group) and in 22 patients without a pouch (Roux-en-Y group). Postoperative symptoms were evaluated with a standard questionnaire, and nutrition was measured by blood chemistry and weight loss.

RESULTS

MCTT was 110 +/- 44 min in the Roux-en-Y group and 117 +/- 44 min in the Pouch group (NS). Eighty-six per cent of the patients in the Roux-en-Y group and 91% of the patients in the Pouch group had bacterial overgrowth (NS). Transit time was shorter in patients with severe dumping than patients without dumping (60 +/- 28 min versus 115 +/- 41 min; P = 0.04). Maximal hydrogen concentration in the glucose breath test correlated negatively with serum albumin and iron concentrations and with postoperative weight loss, and positively with serum alkaline phosphatase activity.

CONCLUSIONS

Bacterial overgrowth is common in the upper intestine after total gastrectomy. Pouch reconstruction does not delay the transit of liquids. Bacterial overgrowth may be one of the main aetiologic factors in postgastrectomy malnutrition.

Metabolism of glycosyl ureides by human intestinal brush border enzymes

13C-labeled glycosyl ureides were recently proposed as a new marker of the orocecal transit time: after passing the small bowel the sugar-urea bond is split by bacterial allantoicase. Further degradation results in 13CO2 which can be measured in the exhaled breath. The aim of this study was to detect an eventual allantoicase-like activity in the human gut and to elucidate the metabolism of glycosyl ureides by human intestinal brush border enzymes. Biopsies of 15 duodenal specimen and 6 colon specimen were homogenised and incubated with several disaccharides and their corresponding disaccharide ureides under various experimental conditions. Hydrolysis of the sugar-urea bond could not be observed neither in the small bowel nor in the colon. However, the conjugation between the two sugars was split. In a modified Dahlqvist assay lactase showed the same kinetics with lactose and lactose ureide as substrates whereas maltose showed a significantly 2.6-fold higher affinity to maltase than maltose ureide (P < 0.001). No major difference between these two substrates could be detected when total maltase activity was inhibited by acarbose. In summary, the human gut tissue possesses no allantoicase-like activity. Therefore, glycosyl ureides seem to be appropriate substances to test the orocecal transit time.

Assessment of orocaecal transit time in cats by the breath hydrogen method: the effects of sedation and a comparison of definitions

Oro-caecal transit times (OCTTs) were assessed in 10 healthy adult cats by the lactulose breath hydrogen method with either no sedation (group A), or after the intramuscular administration of three sedative regimens: a combination of acetylpromazine at 0.1 mg kg-1 with buprenorphine at 10 micrograms kg-1 (group B), ketamine at 5 mg kg-1 with midazolam at 0.1 mg kg-1 (group C), or medetomidine at 50 micrograms kg-1 (group D). For each test, the OCTT was defined by four methods: a visual assessment, the first maintained 4 ppm increase in hydrogen production, and the first maintained 0.5 ml hr-1 increase in hydrogen production assessed by two cumulative sum methods. Depending on the definition, the median OCTTs of the cats were between 113 and 131.5 minutes in group A, 86.5 and 97.5 minutes in group B, 218 and 235.5 minutes in group C and 86.5 and 97.5 minutes in group D. By two of the definitions, the median OCTTs in group C were significantly longer than in group A (P < or = 0.037) and approached significance by the other two definitions. The use of sedatives significantly increased the inter-individual variability of the OCTTs, particularly in groups C and D. There were significant differences between the median OCTTs defined by the four different methods, but all the methods were very highly and significantly correlated (rs < or = 0.9503, P < 0.0001).

Whole-gut transit scintigraphy in the evaluation of small-bowel and colon transit disorders

Scintigraphic methods for performing gastric emptying and colon transit studies are now well standardized. Although not as well established, several methods have been proposed for measuring small-bowel transit. The measurement of orocecal transit time appears to be a practical scintigraphic measurement of small-bowel transit. When combined into a single test of gastric emptying, small-bowel, and colon transit, whole-gut transit scintigraphy is an important, noninvasive tool for documenting dysmotility of any segment of the gastrointestinal tract. Despite attempts to simplify the study, whole-gut transit scintigraphy still requires a significant commitment of time and equipment. As with other gastrointestinal studies, each laboratory must determine which protocol best fits its clinical needs, equipment, and staffing. Attention must be paid to adhere to established protocols, or normal values will need to be determined for each laboratory. Despite these difficulties, whole-gut transit scintigraphy now represents an important clinical tool for the evaluation of patients with a wide range of abdominal complaints.

Erythromycin shortens orocaecal transit time in diabetic male subjects: a double-blind placebo-controlled study

BACKGROUND

The effects of erythromycin on small bowel motility are controversial. Orocaecal transit time (OCTT) is considered to be a valid measure of small bowel motility.

METHODS

We studied the effect of erythromycin on OCTT in diabetic male subjects in a double-blind placebo-controlled crossover fashion. After an overnight fast, subjects received erythromycin 500 mg, 250 mg or placebo, on 3 different days. A standard solid meal containing 20 g lactulose was administered 30 min after the erythromycin ingestion. Exhaled breath was collected and hydrogen concentration was assessed over 5 h. Breath hydrogen concentrations for each session were analysed over time by a generalized logistic function generating a sigmoidal curve. Front transit time was recorded as the time point when a sustained rise in breath hydrogen concentration of at least 5 p.p.m. was first observed.

RESULTS

The mean +/- S.E.M. time taken for the front of the meal to reach the caecum was 92.5 +/- 9.5, 86.1 +/- 16.5 and 62.3 +/- 12.1 min for placebo, erythromycin 250 mg and erythromycin 500 mg, respectively. The OCTT was significantly decreased with erythromycin 500 mg compared to placebo (P < 0.05).

CONCLUSION

Oral administration of 500 mg erythromycin has prokinetic effect on orocaecal transit in male patients with diabetes mellitus.

A comparison of orocaecal transit times assessed by the breath hydrogen test and the sulphasalazine/sulphapyridine method in healthy beagle dogs

Orocaecal transit time (OCTT) was assessed in six healthy beagles by means of the breath hydrogen test (BH2T) and the sulphasalazine/sulphapyridine method (SLZ) after the administration of a test meal of canned food mixed with sulphasalazine. Orocaecal transit time was defined as the time taken from the oral administration of the test meal to the time when the first portion of the meal reached the colon. In five of the dogs the OCTTs assessed by the BH2T were shorter than those measured by the SLZ method by 30, 15, 45, 30 and 45 minutes. However, the median OCTT assessed by the BH2T (135 minutes, range 120 to 195 minutes) was not significantly different from that measured by the SLZ (180 minutes, range 150 to 210 minutes) and was highly correlated with it (r = 0.94, P = 0.016). The sixth dog maintained baseline hydrogen and plasma sulphapyridine readings throughout the monitoring period and the OCTT could not be measured.

Milk is a useful test meal for measurement of small bowel transit time

To improve and standardize the measurement of small bowel transit time, milk was employed for the test meal instead of the conventional lactulose meal. Although 92% of the subjects were lactase deficient, only 2% were milk intolerant and 13% were lactose intolerant. Small bowel transit time with milk (milk breath hydrogen test) was 113 +/- 9 min (mean +/- SE, n = 20); the normal range calculated from the mean +/- 2 SD was 31-195 min. The coefficient of variation in the milk hydrogen breath test was 13 +/- 4% (n = 6), whereas in the lactulose hydrogen breath test, it was 39 +/- 16% (n = 10). The frequency of non-hydrogen producers, the occurrence of discomfort, and the reproducibility were better, though not significantly so, in the milk hydrogen breath test than in the lactulose. Since lactase activity in the intestine is variable in lactase-deficient subjects, small bowel transit times for milk may change from subject to subject. However, individual reproducibility of the milk hydrogen breath test is good. It could be useful for pharmacological experiments using paired comparison, for screening tests, or for the follow up of diseases in which small bowel transit time is affected.

Gastrointestinal transit through esophagus, stomach, small and large intestine in patients with progressive systemic sclerosis

Liquid esophageal transit and gastric emptying, mouth-to-cecum transit, and whole gut transit of a solid-liquid meal were measured in 14 patients with PSS, 16 control subjects (esophageal transit), and 20 control subjects (gastrointestinal transit), respectively, by using scintigraphic techniques, the hydrogen breath test, and stool markers. In patients with PSS, the glucose hydrogen breath test for detection of small intestinal overgrowth was performed and various gastrointestinal symptoms were determined. Esophageal transit and gastric emptying were significantly prolonged in PSS patients with 11 of 14 PSS patients (79%) disclosing delayed esophageal transit and eight of 14 PSS patients (57%) disclosing delayed gastric emptying. All PSS patients with prolonged gastric emptying also had delayed esophageal transit and there was a significant positive correlation between esophageal transit and gastric emptying (r = 0.696, P < 0.01). No significant differences between PSS patients and controls were detected concerning mouth-to-cecum transit and whole gut transit, but abnormally delayed mouth-to-cecum transit was found in four of 10 PSS patients (40%) and abnormally prolonged whole gut transit was detected in three of 13 PSS patients (23%). Small bacterial overgrowth was diagnosed in three of 14 PSS patients (21%). Delayed esophageal transit and gastric emptying were associated with dysphagia, retrosternal pain, and epigastric fullness, while prolonged whole gut transit was associated with constipation. It is concluded that delayed gastric emptying is frequently associated with esophageal transit disorders in PSS patients and may be one important factor for the development of gastroesophageal reflux disease in these patients.

Lactulose hydrogen breath test in orocecal transit assessment. Critical evaluation by means of scintigraphic method

Orocecal transit time can be studied easily using the hydrogen breath test with lactulose, but the method has some important limitations. The orocecal transit time of 10 patients suffering from irritable bowel syndrome was measured twice, at a one-week interval, by breath test and scintigraphy simultaneously using an aqueous solution of 20 g lactulose containing 74 MBq of [99mTc]DTPA. Abdominal radioactivity and alveolar hydrogen values obtained every 5 min were noted and used to obtain the following: orocecal transit time by the two methods; ileocecal lactulose flow; total and per gram of lactulose hydrogen production; mean hydrogen concentration during the right colon filling; and measurement error of the breath test with respect to the scintigraphy. In the case of the breath test, the orocecal transit time intrapatient reproducibility was better (coefficient of variation = 13.5%) when a hydrogen threshold increment of 5 ppm was used; the best correlation with the scintigraphic measurement was observed at this threshold (r = 0.90, P < 0.001). The breath test overestimated orocecal transit time with the error correlating negatively and significantly with the total hydrogen production and, particularly, the mean hydrogen concentration (r = 0.79, P < 0.01): for a mean hydrogen concentration of more than 15 ppm, the error was negligible, while within this value there was a noticeable overestimation. To conclude, the lactulose hydrogen breath test is capable of giving an accurate measurement of orocecal transit time if a hydrogen threshold increment of 5 ppm is chosen and if the mean hydrogen concentration in the first 30 min of the right colon filling is taken into account.

Magnetic markers as a noninvasive tool to monitor gastrointestinal transit

A novel method to monitor gastrointestinal transit of solid oral dosage forms or nutrients is presented, providing a simultaneous recording of gastrointestinal motility of the traversed section. Based on the measurement of the magnetic field of an ingested magnetized marker, its location is found by fitting a magnetic dipole field to the measured data.

Decreased orocaecal transit time, as measured by the exhalation of hydrogen, in hyperthyroid cats

Orocaecal transit time was assessed in healthy cats and cats with hyperthyroidism by means of the breath hydrogen test using a standard liquid meal with lactulose. The median transit time in 10 healthy cats was 98 minutes (range 60 to 150 minutes) and 90 minutes (range 75 to 150 minutes) in a repeated assessment. The median transit time in 10 cats with hyperthyroidism was 53 minutes (range 45 to 150 minutes) which was significantly more rapid (P < 0.05) than in the healthy cats.

The effect of short-term dietary fibre administration on oro-caecal transit time in dogs

The effect on oro-caecal transit time of addition of soluble (guar gum) and insoluble (wheat bran) fibre to diets fed to seven healthy dogs at levels that have been shown to reduce post-prandial hyperglycaemia was assessed. Oro-caecal transit time was measured by sequential analysis of exhaled breath hydrogen levels. Median oro-caecal transit times were 105 min (range: 45 to 135), 113 min (range: 53 to 203) and 105 min (range: 75 to 195) after administration of a 770 g standard meal of canned food alone, or with the addition of 7.7 g wheat bran or guar gum, respectively. There was no significant difference between the oro-caecal transit times (p = 0.964) for the different diets when the results for all the dogs were pooled. The difference between diets was statistically significant for both maximal post-prandial hyperglycaemia (p = 0.035) and area of post-prandial hyperglycaemia under the post-prandial glucose curve (p = 0.006).

Relation of symptoms to impaired stomach, small bowel, and colon motility in long-standing diabetes

Stomach, intestinal, and colonic transit were measured in males with insulin-requiring diabetes of greater than 10 years' duration to compare with symptoms and to estimate the medical significance. For all diabetics only the symptom constipation correlated with the appropriate regional delayed transit. Diabetics with delayed transit in any region, however, had more overall gastrointestinal symptoms. Diabetics with delayed transit had disease of significantly longer duration than those without delay. Delayed transit was common in the diabetics selected for study with 21 of 54 stomachs, 10 of 20 small intestines, and 14 of 20 colons showing impairment. Of 35 diabetics with impaired transit at one or more locations, only seven were judged of medical importance and five of these responded to treatment. In this study, delayed transit was frequent; in the one fifth requiring management, the symptoms related closely to the region impaired.

Non-invasive assessment of gastrointestinal motility disorders in diabetic patients with and without cardiovascular signs of autonomic neuropathy

Twenty six patients with insulin dependent diabetes mellitus underwent a gastric emptying test, a gall bladder contraction test, an orocaecal transit study, and a colon transit test. Eleven patients had signs of cardiovascular autonomic neuropathy, 15 patients were without signs of cardiovascular autonomic neuropathy. Mean gastric clearance of radioopaque markers ingested with a meal averaged 29.5 (2.3) markers per six hours in subjects without cardiovascular autonomic neuropathy compared with 17.8 (2.3) markers per six hours in patients with cardiovascular autonomic neuropathy (p < 0.02). Gall bladder emptying in response to graded CCK8 stimulation was impaired in five of 11 patients with cardiovascular autonomic neuropathy, whereas it was normal in the patients without cardiovascular autonomic neuropathy (p < 0.01). Oral caecal transit times were not significantly different in the two patient groups, whereas colonic transit was slower in the patients with cardiovascular autonomic neuropathy compared with the group without cardiovascular autonomic neuropathy (p < 0.02). There was no correlation between disturbed gastric clearance, impaired gall bladder contraction, and prolonged colonic transit time in the patients with cardiovascular autonomic neuropathy nor was there a correlation between any disturbed motor function and age or duration of diabetes. It is concluded that autonomic neuropathy can affect motor functions throughout the gastro-intestinal tract. Any disturbed motor function in the gut could therefore be one of the numerous expressions of diabetic neuropathy affecting the cardiovascular, the endocrine or the gastrointestinal system.

Effects of alpha-glucosidase inhibitors on mouth to caecum transit time in humans

The alpha-glucosidase inhibitors acarbose and miglitol have been successfully used to control postprandial hyperglycaemia in diabetics. They probably work by slowing carbohydrate digestion and absorption, but their effect on mouth to caecum transit time has not been studied. The effect acarbose (100 mg), miglitol (100 mg), and placebo on mouth to caecum transit time (380 kcal breakfast with 20 g of lactulose) was investigated in 18 normal volunteers using breath hydrogen analysis. Both miglitol and acarbose significantly increased breath hydrogen excretion (F2,34 = 6.31, p = 0.005) and shortened the mouth to caecum transit time (F2,34 = 3.49, p = 0.04) after breakfast compared with placebo. There was a significant negative correlation between breath hydrogen excretion and mouth to caecum transit time suggesting that with shorter transit times significantly more carbohydrates were spilled into the colon. These results indicate that alpha-glucosidase inhibitors accelerate mouth to caecum transit time by inducing carbohydrate malabsorption.

Breath hydrogen test using water-diluted lactulose in patients with gastrointestinal amyloidosis

To investigate small bowel motility in gastrointestinal amyloidosis, lactulose breath hydrogen tests were performed on 16 patients with histologically proven amyloidosis and 12 age- and sex-matched controls. Fasting breath hydrogen concentration (FBHC) was not significantly different between the two groups, but there was a tendency for FBHC in symptomatic amyloidosis patients (median 31.5, range 3-78 ppm) to be higher than in asymptomatic amyloidosis patients (4, 0-34 ppm, 0.05 less than P less than 0.1) and controls (6, 1-19 ppm, 0.05 less than P less than 0.1). Orocecal transit time (OCTT) was significantly delayed in the amyloidosis group (median 150, range 40-220 min) when compared to the controls (60, 20-110 min, P less than 0.01), but OCTT was not statistically different between symptomatic and asymptomatic amyloidosis patients. These data suggest an impaired motility of the stomach and small intestine in gastrointestinal amyloidosis and the possible role of small intestinal dysfunction such as bacterial overgrowth and malabsorption in the occurrence of symptoms in this disorder.

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.