Carbohydrate Malabsorption: Quantification by Methane and Hydrogen Breath Tests

Rumessen JJ, Nordgaard-Andersen I, Gudmand-Høyer E. Carbohydrate malabsorption: quantification by methane and hydrogen breath tests. Scand J Gastroenterol 1994;29:826-832.

Background: Previous studies in small series of healthy adults have suggested that parallel measurement of hydrogen and methane resulting from gut fermentation may improve the precision of quantitative estimates of carbohydrate malabsorption. Systematic, controlled studies of the role of simultaneous hydrogen and methane measurements using end-expiratory breath test techniques are not available. Methods: We studied seven healthy, adult methane and hydrogen producers and seven methane non-producers by means of end-expiratory breath test techniques. Breath gas concentrations and gastrointestinal symptoms were recorded at intervals for 12 h after ingestion of 10,20, and 30 g lactulose. Results: In the seven methane producers the excretion pattern was highly variable; the integrated methane responses were disproportional and not reliably reproducible. However, quantitative estimates of carbohydrate malabsorption on the basis of individual areas under the methane and hydrogen excretion curves (AUCs) tended to improve in methane producers after ingestion of 20 g lactulose by simple addition of AUCs of methane to the AUCs of the hydrogen curves. Estimates were no more precise in methane producers than similar estimates in non-producers. Gastrointestinal symptoms increased significantly with increasing lactulose dose; correlation with total hydrogen and methane excretion was weak. Conclusions: Our study suggests that in methane producers, simple addition of methane and hydrogen excretion improves the precision of semiquantitative measurements of carbohydrate malabsorption. The status of methane production should, therefore, be known to interpret breath tests semiquantitatively. The weak correlation between hydrogen and methane excretion and gas-related abdominal complaints suggests that other factors than net production of these gases may be responsible for the symptoms.     

Probiotic effects on intestinal fermentation patterns in patients with irritable bowel syndrome

AIM： To determine whether Lactobacillus casei strain Shirota （Yakult） can alter small intestinal bacterial overgrowth （SIBO）, as tested by the lactulose breath test, and whether this is associated with changes in symptoms in irritable bowel syndrome （IBS）. METHODS： 18 patients with IBS （Rome Ⅱ criteria）, who showed an early rise in breath hydrogen with lactulose （ERBHAL）, consumed 65 mL of Yakult daily for 6 wk. Lactulose breath test was repeated at the end of the treatment period. Symptoms were recorded daily using a 10 cm visual analogue scale. RESULTS： 14 patients completed the study, 9 （64%） had reversal of ERBHAL, with the median time of first rise in breath hydrogen increasing from 45 to 75 min （P = 0.03）. There was no significant improvement in the symptom score with probiotic therapy, except for wind （P = 0.04）. Patients commencing with at least moderate symptoms and who no longer had ERBHAL at the end of treatment, showed improvement in the overall symptoms scores [median final score 5.3 （IQR 3.9-5.9）, 55% reduction; n = 6] to a greater extent than those who had had persisting ERBHAL [final score 6.9 （5.0-7.0）, 12% reduction; n = 5; P = 0.18]. CONCLUSION： Yakult is effective in altering fermentation patterns in the small bowel, consistent with reducing SIBO. The loss of ERBHAL was associated with reduced symptoms. The true interpretation of these findings awaits a randornised, controlled trial.     

Comparison of abdominal bloating severity between irritable bowel syndrome patients with high and low levels of breath hydrogen excretion in a lactulose breath test

BackgroundThere is growing evidence that gut flora plays a role in the development of Irritable Bowel Syndrome (IBS). Abdominal bloating is a common symptom in these patients and the severity of this symptom could be related to the variations in their fermentative profiles, obtained by measuring the levels of breath hydrogen excretion after lactulose ingestion.AimsOur objective was to determine the difference in abdominal bloating severity between IBS patients with high vs low levels of breath hydrogen excretion after lactulose administration.MethodsLactulose breath tests were carried out on IBS patients in our institution between July 2009 and August 2010. Patients were requested to fill out a validated questionnaire to assess the severity of their symptoms. Abdominal bloating severity score was compared among patients with high and low breath hydrogen levels.ResultsA total of 234 patients were enrolled. There was a statistically significant difference in the abdominal bloating severity score between groups: 7.0 (5.7-8.0) vs 6.5 (5.0-7.5), p=0.001. The comparison among IBS patients with constipation (IBS-C) in both groups also showed a statistically significant difference: 7.5 (6.0-8.5) vs 5.8 (3.5-7.2), p=0.0051.ConclusionsThose patients with a low level of breath hydrogen excretion after lactulose ingestion presented with significantly greater abdominal bloating than those with a high level of breath hydrogen excretion.     

Peppermint oil (Mintoil) in the treatment of irritable bowel syndrome: A prospective double blind placebo-controlled randomized trial

INTRODUCTION: The use of peppermint oil in treating the irritable bowel syndrome has been studied with variable results probably due to the presence of patients affected by small intestinal bacterial overgrowth, lactose intolerance or celiac disease that may have symptoms similar to irritable bowel syndrome. AIM: The aim of the study was to test the effectiveness of enteric-coated peppermint oil in patients with irritable bowel syndrome in whom small intestinal bacterial overgrowth, lactose intolerance and celiac disease were excluded. METHODS: Fifty-seven patients with irritable bowel syndrome according to the Rome II criteria, with normal lactose and lactulose breath tests and negative antibody screening for celiac disease, were treated with peppermint oil (two enteric-coated capsules twice per day or placebo) for 4 weeks in a double blind study. The symptoms were assessed before therapy (T(0)), after the first 4 weeks of therapy (T(4)) and 4 weeks after the end of therapy (T(8)). The symptoms evaluated were: abdominal bloating, abdominal pain or discomfort, diarrhoea, constipation, feeling of incomplete evacuation, pain at defecation, passage of gas or mucus and urgency at defecation. For each symptom intensity and frequency from 0 to 4 were scored. The total irritable bowel syndrome symptoms score was also calculated as the mean value of the sum of the average of the intensity and frequency scores of each symptom. RESULTS: At T(4), 75% of the patients in the peppermint oil group showed a >50% reduction of basal (T(0)) total irritable bowel syndrome symptoms score compared with 38% in the placebo group (P<0.009). With peppermint oil at T(4) and at T(8) compared with T(0) a statistically significant reduction of the total irritable bowel syndrome symptoms score was found (T(0): 2.19+/-0.13, T(4): 1.07+/-0.10*, T(8): 1.60+/-0.10*, *P<0.01 compared with T(0), mean+/-S.E.M.), while no change was found with the placebo. CONCLUSION: A 4 weeks treatment with peppermint oil improves abdominal symptoms in patients with irritable bowel syndrome.     

Colonic hydrogen absorption: quantification of its effect on hydrogen accumulation caused by bacterial fermentation of carbohydrates.

The aim of the study was to assess (quantitatively) colonic hydrogen absorption. Hydrogen volumes in flatus and breath were measured over periods of six hours in normal subjects during fasting and after ingestion of the non-absorbable carbohydrate lactulose to simulate the effect of fermentable dietary fibres. If less than 76 ml/6 h of hydrogen accumulated in the colon then all of it was absorbed, as suggested by the intercept of the regression line of the correlation between hydrogen volumes in flatus and breath after ingestion of lactulose. As total flatus volume increased, efficiency of colonic hydrogen absorption decreased from 90% to 20%. The positive correlation between hydrogen volumes of flatus and breath showed that the eightfold interindividual differences in flatus volume after ingestion of 12.5 g of lactulose were caused by differences in bacterial net gas production, not gas absorption. Differences in colonic gas emptying rate are the consequence rather than the cause of interindividual differences in flatus volume. In conclusion: (1) colonic hydrogen absorption is highly effective at low colonic hydrogen accumulation rates, but not at higher accumulation rates; (2) ineffective colonic gas absorption is the consequence and not the cause of high colonic gas accumulation rate after ingestion of non-absorbable carbohydrates; and (3) future therapeutic approaches to the large interindividual variability in colonic gas accumulation after ingestion of poorly absorbable fermentable carbohydrates, such as some kinds of dietary fibres, should be directed towards altering colonic bacterial metabolism.     

Relationships Among the Lactulose Breath Test,Intestinal Gas Volume,and Gastrointestinal Symptoms in Patients with Irritable Bowel Syndrome

Background and Aims  

Irritable bowel syndrome (IBS) patients frequently complain of gas-related symptoms, and the lactulose breath test (LBT) is a test that assesses the amount of fermented gas generated by bacteria in the bowel. We aimed to assess the relationship among intestinal gas volume, LBT result, and gastrointestinal symptom score in healthy control and functional bowel disorder (FBD) subjects.     

Bacterial concepts in irritable bowel syndrome

An overlap of symptoms in irritable bowel syndrome (IBS) exists across subtype groups. Symptoms include intestinal gas, diarrhea, dyspepsia, bloating, abdominal pain, and constipation. The unifying symptom may be excessive intestinal gas as a by-product of intestinal microbial fermentation. Abnormal fermentation of food takes place when gut microbes expand proximally into the small intestine instead of being confined predominantly to the colon. Such proximal expansion of indigenous gut microbes or small intestinal bacterial overgrowth (SIBO) may lead to activation of host mucosal immunity and an increase in intestinal permeability to result in flu-like extra-intestinal symptoms that accompany the classic IBS symptoms of altered bowels. The presence of methane on lactulose breath testing is associated with constipation-predominant IBS. Antibiotic therapy may be appropriate to treat underlying SIBO in IBS patients. Seventy-five percent improvement of IBS symptoms was reported in a double-blind, placebo-controlled study once antibiotics succeeded in treating bacterial overgrowth. Once a good clinical response and normalization of the lactulose breath test are achieved, a prokinetic agent may be used to stimulate phase III of interdigestive motility to delay relapse of bacterial overgrowth.     

Methane production during lactulose breath test is associated with gastrointestinal disease presentation

It has recently been determined that there is an increased prevalence of bacterial overgrowth in IBS. Since there are two gases (hydrogen and methane) measured on lactulose breath testing, we evaluated whether the different gas patterns on lactulose breath testing coincide with diarrhea and constipation symptoms in IBS and IBD. Consecutive patients referred to the gastrointestinal motility program at Cedars-Sinai Medical Center for lactulose breath testing were given a questionnaire to evaluate their gastrointestinal symptoms. Symptoms were graded on a scale of 0–5. Upon completion of the breath test, the results were divided into normal, hydrogen only, hydrogen and methane, and methane only positive breath tests. A comparison of all subjects and IBS subjects was undertaken to evaluate diarrhea and constipation with regards to the presence or absence of methane. This was further contrasted to Crohn's and ulcerative colitis (UC) patients in the database. After exclusion criteria, 551 subjects from the database were available for comparison. Of the 551 subjects (P < 0.05, one-way ANOVA) and in a subgroup of 296 IBS subjects (P < 0.05, one-way ANOVA), there was a significant association between the severity of reported constipation and the presence of methane. The opposite was true for diarrhea (P < 0.001). If a breath test was methane positive, this was 100% associated with constipation predominant IBS. Furthermore, IBS had a greater prevalence of methane production than Crohn's or UC. In fact, methane was almost nonexistent in the predominantly diarrheal conditions of Crohn's and UC. In conclusion, a methane positive breath test is associated with constipation as a symptom.     

Lactulose breath test results in patients with persistent abdominal symptoms following Giardia lamblia infection

OBJECTIVE: Bacterial overgrowth has been implicated in the pathogenesis of irritable bowel syndrome (IBS). The objective of this study was to investigate whether post-infectious IBS following Giardia lamblia infection is related to intestinal bacterial overgrowth, as diagnosed by the lactulose breath test (LBT). MATERIAL AND METHODS: Seventy-seven patients with persistent gastrointestinal complaints related to a recent outbreak of G. lamblia infection were included in the study. Despite one or several courses of treatment with metronidazole during the previous months, 23 of the patients were still stool positive for G. lamblia, whereas the remaining 54 patients had cleared the infection. All patients and 42 healthy volunteers underwent a LBT with 10 g lactulose, and their customary and post-LBT abdominal symptoms were scored. RESULTS: Ninety-five percent of the patients had IBS. Lactulose-induced hydrogen breath excretion was not significantly different in patients and controls. Customary and post-LBT symptoms were abnormally high in the patients, irrespective of both G. lamblia infection status and LBT results. Furthermore, lactulose challenge replicated the patients' customary complaints in 70% of the patients. CONCLUSIONS: Gastrointestinal complaints in patients with persistent or cleared giardiasis were unrelated to hydrogen breath excretion after lactulose challenge. Post-giardiasis IBS cannot be ascribed to intestinal bacterial overgrowth, as diagnosed by LBT.     

Role of colonic fermentation in the perception of colonic distention in irritable bowel syndrome and functional bloating.

BACKGROUND & AIMS: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: A subgroup of patients with functional gastrointestinal disorders and moderate to severe bloating might have hypersensitivity to products of colonic fermentation.     

Relevance of abdominal gas analysis and transit study after colorectal cancer surgery

BACKGROUND: Colon gas volume analysis using abdominal radiographs is an objective and reproducible method for evaluating functional bowel disorders. The aim of this study was to clarify the relevance of colon gas distribution and transit time in rectosigmoid cancer patients after surgery. METHODS: Segmental colon gas volume score was calculated using plain abdominal radiography and evaluated in 40 patients who had undergone sphincter-saving resection. Segmental colonic transit time was analysed using radiopaque markers in the same patients. RESULTS: Transit times in the right colon (RCT) were 15.3 +/- 1.1 h and in the left colon (LCT) 11.2 +/- 1.1 h. Gas volume scores in the RCS and LCS were 1.10 +/- 0.13% and 1.06 +/- 0.14%, respectively. Neither colonic transit time nor colon gas volume score correlated with the operation methods for rectosigmoid colon cancer. A positive correlation of RCS and a negative correlation of LCS/RCS with ageing were noted in male patients but not in female patients. There was no correlation between RCT and RCS (r = 0.028); however, LCT correlated with LCS (r = 0.318, P < 0.05). The ratio of colonic transit time (LCT/RCT) was 0.84 +/- 0.10, while that of colon gas volume score (LCS/RCS) was 1.29 +/- 0.21. There was a significant correlation between LCT/RCT and LCS/RCS (r = 0.541, P < 0.001). CONCLUSIONS: Analysis of colon gas volume is useful for evaluating colonic transit time in rectosigmoid cancer patients after sphincter-saving surgery.     

Quantitative analysis of bowel gas using plain abdominal radiograph in patients with irritable bowel syndrome

OBJECTIVE: Ideally, the diagnosis of irritable bowel syndrome (IBS) would be achieved using a minimal number of procedures. It is presumed that bowel gas is related to IBS, and it is easily visualized by plain abdominal radiograph. In the present study, to clarify the relationship between IBS and the quantity of bowel gas, the measured bowel gas volume using plain abdominal radiographs was compared with the pathology of IBS. METHODS: Plain abdominal radiographs were digitized and transmitted to a computer (computed radiography) in 30 IBS patients and 30 normal controls. The quantity of bowel gas, determined as the pixel value on images and standardized by physique, was defined as the gas volume score (GVS). Using the mean +/- 2SD of GVS in the control group as the normal score, IBS patients were divided into three groups: high, normal, and low. To examine the sequential reproducibility of a similar quantity of bowel gas, a second plain abdominal radiography was performed about 2 months later, and the GVS were compared. The colonic transit time was determined using radiopaque markers. RESULTS: There was a strong correlation between the quantities of bowel gas measured by two independent gastroenterologists. The mean GVS of IBS patients was significantly higher than that in the control group (p < 0.001). The sequential reproducibility was recognized in all 10 IBS patients. There was no significance between colonic transit time and GVS, nor between symptoms and GVS. CONCLUSIONS: Abdominal gas was analyzed objectively by using GVS, and GVS was considered to represent a useful tool for the diagnosis of IBS.     

The degree of breath methane production in IBS correlates with the severity of constipation

BACKGROUND: Recent work has demonstrated that among irritable bowel syndrome (IBS) subjects, methane on lactulose breath test (LBT) is nearly universally associated with constipation predominance. This work has been based on subjective constipation outcomes. In this study, methane is compared to constipation in another population of IBS subjects with constipation being determined both subjectively and objectively. METHODS: A nested study was conducted in subjects enrolled in a double-blind randomized placebo-controlled study. After consent, subjects were asked to complete a stool diary for 7 days. This included logging of all bowel movements that week as well as documenting the stool consistency for each during the same period using the Bristol Stool Score. After 7 days, subjects were asked to rate their symptoms on a visual analogue scale (VAS) score (0-100 mm) for diarrhea and constipation. They then had an LBT to evaluate both methane and hydrogen profiles over 180 min. Subjects with methane were compared to those without methane for Bristol Stool Score, stool frequency, as well as VAS scores for diarrhea and constipation. The degree of constipation was then compared to the quantity of methane production on LBT based on area under the curve. RESULTS: Among 87 subjects, 20 (23.8%) produced methane. IBS subjects with methane had a mean constipation severity of 66.1 +/- 36.7 compared to 36.2 +/- 30.8 for nonmethane producers (P < 0.001). The opposite was noted for diarrhea (P < 0.01). On LBT, the quantity of methane seen on breath test was directly proportional to the degree of constipation reported (r = 0.60, P < 0.01). In addition, greater methane production correlated with a lower stool frequency (r =-0.70, P < 0.001) and Bristol Stool Score (r =-0.58, P < 0.01). CONCLUSION: Methane on LBT is associated with constipation both subjectively and objectively. The degree of methane production on breath test appears related to the degree of constipation.     

Detection of bacterial overgrowth in IBS using the lactulose H2 breath test: comparison with 14C-D-xylose and healthy controls

OBJECTIVES Recent reports suggest bacterial overgrowth is commonly associated with irritable bowel syndrome (IBS) when diagnosed using the lactulose hydrogen breath test (LHBT). We employed this test to examine whether similar findings exist in a geographically distinct population of Rome II positive IBS patients and compared it to the 14C-D-xylose breath test, a test with acknowledged greater specificity for bacterial overgrowth. METHODS: In the first series, Rome II IBS patients underwent a 10 g lactulose breath test and a standardized 1 g 14C-D-xylose breath test and answered IBS symptom questionnaires. A positive test required an elevated breath hydrogen concentration within 90 min, two distinct peaks, and an increase >20 ppm. In a second series, control patients lacking gastrointestinal symptoms underwent a lactulose breath test. A positive test required an elevation of breath hydrogen >20 ppm within 90 or 180 min. These criteria were also applied to lactulose breath tests from IBS cases in series one. RESULTS: The IBS patients were predominantly female (64%) and most reported severe symptoms (80%). The majority had diarrhea predominant symptoms (63%) and only 3% were constipation predominant. In the first series, only 10% of patients had a positive lactulose breath test and 13% had a positive 14C-D-xylose test. In the second series, the number of abnormal LHBTs was much higher but no differences were found between IBS patients and controls. CONCLUSION: The lactulose breath test did not reliably detect a common association between bacterial overgrowth and IBS in our patient population.     

Effect of simethicone on lactulose-induced H2 production and gastrointestinal symptoms.

The results of studies of the effect of simethicone on abdominal gas-related symptoms have been contradictory. In a randomized, double-blind cross-over study, 10 healthy volunteers were given 30 g lactulose and 600 mg simethicone or placebo. End-expiratory breath samples were collected and analyzed for H2 and gastrointestinal symptoms registered. There were no differences in biochemical parameters or symptom score between simethicone and placebo. In contrast to previous studies, we used a sufficiently large dose of lactulose to produce gastrointestinal symptoms, a higher dose of simethicone and placebo tablets containing the same additives as the simethicone tablets. There was no demonstrable effect of simethicone on symptoms or intestinal gas production caused by carbohydrate malabsorption.     

Gas Volume Analysis and Postoperative Bowel Functional Disorders in Patients Who Received Anterior Resection for Rectal Cancer

PURPOSE: Colon gas analysis using abdominal radiography has been reported as a reliable method for assessing functional bowel disorders. The aim of this study was to clarify the relevance of colon gas distribution in postoperative disorders such as constipation and feelings of incomplete evacuation following rectal cancer operation. METHODS: Colon gas volume score was calculated using plain abdominal radiographs and evaluated in 50 patients who had received low anterior resections. Twenty-one constipated patients who required laxatives and 29 patients who did not were compared in terms of colon gas distribution. In addition, 32 patients with postoperative feelings of incomplete evacuation and 18 patients without such feelings were assessed in similar fashion. RESULTS: Left colon gas scores in patients who required laxatives were significantly higher (2.82 ± 3.23 percent) than in nonusers (1.21 ± 0.96 percent; P < 0.01). Patients with feelings of incomplete evacuation displayed significantly higher left side colon gas scores (2.51 ± 2.66 percent) than those without such feelings (0.77 ± 0.81 percent; P < 0.0001). CONCLUSION: Patients with postoperative functional bowel disorders such as constipation or feelings of incomplete evacuation may experience relatively high volumes of gas in the left colon.     

Ileocecal valve dysfunction in small intestinal bacterial overgrowth: A pilot study

AIM: To explore whether patients with a defective ileocecal valve (ICV)/cecal distension reflex have small intestinal bacterial overgrowth.METHODS: Using a colonoscope, under conscious sedation, the ICV was intubated and the colonoscope was placed within the terminal ileum (TI). A manometry catheter with 4 pressure channels, spaced 1 cm apart, was passed through the biopsy channel of the colonoscope into the TI. The colonoscope was slowly withdrawn from the TI while the manometry catheter was advanced. The catheter was placed across the ICV so that at least one pressure port was within the TI, ICV and the cecum respectively. Pressures were continuously measured during air insufflation into the cecum, under direct endoscopic visualization, in 19 volunteers. Air was insufflated to a maximum of 40 mmHg to prevent barotrauma. All subjects underwent lactulose breath testing one month after the colonoscopy. The results of the breath tests were compared with the results of the pressures within the ICV during air insufflation.RESULTS: Nineteen subjects underwent colonoscopy with measurements of the ICV pressures after intubation of the ICV with a colonoscope. Initial baseline readings showed no statistical difference in the pressures of the TI and ICV, between subjects with positive lactulose breath tests and normal lactulose breath tests. The average peak ICV pressure during air insufflation into the cecum in subjects with normal lactulose breath tests was significantly higher than cecal pressures during air insufflation (49.33 ± 7.99 mmHg vs 16.40 ± 2.14 mmHg, P = 0.0011). The average percentage difference of the area under the pressure curve of the ICV from the cecum during air insufflations in subjects with normal lactulose breath tests was significantly higher (280.72% ± 43.29% vs 100% ± 0%, P = 0.0006). The average peak ICV pressure during air insufflation into the cecum in subjects with positive lactulose breath tests was not significantly different than cecal pressures during air insufflation 21.23 ± 3.52 mmHg vs 16.10 ± 3.39 mmHg. The average percentage difference of the area under the pressure curve of the ICV from the cecum during air insufflation was not significantly different 101.08% ± 7.96% vs 100% ± 0%. The total symptom score for subjects with normal lactulose breath tests and subjects with positive lactulose breath tests was not statistically different (13.30 ± 4.09 vs 24.14 ± 6.58). The ICV peak pressures during air insufflations were significantly higher in subjects with normal lactulose breath tests than in subjects with positive lactulose breath tests (P = 0.005). The average percent difference of the area under the pressure curve in the ICV from cecum was significantly higher in subjects with normal lactulose breath tests than in subjects with positive lactulose breath tests (P = 0.0012). Individuals with positive lactulose breath tests demonstrated symptom scores which were significantly higher for the following symptoms: not able to finish normal sized meal, feeling excessively full after meals, loss of appetite and bloating.CONCLUSION: Compared to normal, subjects with a positive lactulose breath test have a defective ICV cecal distension reflex. These subjects also more commonly have higher symptom scores.     

硫化氢呼气试验在小肠细菌过度生长诊断中的应用价值初探

目的:探究硫化氢呼气试验（hydrogen sulfide breath test,SBT）在小肠细菌过度生长（small intestinal bacterial overgrowth, SIBO）诊断中的应用价值。方法:纳入2019年4—12月某高校学生,进行消化道症状和1周膳食问卷调查,以及乳果糖氢-甲烷呼气试验...     

Relevance of Abdominal Gas Analysis and Transit Study after Colorectal Cancer Surgery

Background: Colon gas volume analysis using abdominal radiographs is an objective and reproducible method for evaluating functional bowel disorders. The aim of this study was to clarify the relevance of colon gas distribution and transit time in rectosigmoid cancer patients after surgery. Methods: Segmental colon gas volume score was calculated using plain abdominal radiography and evaluated in 40 patients who had undergone sphincter-saving resection. Segmental colonic transit time was analysed using radiopaque markers in the same patients. Results: Transit times in the right colon (RCT) were 15.3 ± 1.1 h and in the left colon (LCT) 11.2 ± 1.1 h. Gas volume scores in the RCS and LCS were 1.10 ± 0.13% and 1.06 ± 0.14%, respectively. Neither colonic transit time nor colon gas volume score correlated with the operation methods for rectosigmoid colon cancer. A positive correlation of RCS and a negative correlation of LCS/RCS with ageing were noted in male patients but not in female patients. There was no correlation between RCT and RCS (r = 0.028); however, LCT correlated with LCS (r = 0.318, P < 0.05). The ratio of colonic transit time (LCT/RCT) was 0.84 ± 0.10, while that of colon gas volume score (LCS/RCS) was 1.29 ± 0.21. There was a significant correlation between LCT/RCT and LCS/RCS (r = 0.541, P < 0.001). Conclusions: Analysis of colon gas volume is useful for evaluating colonic transit time in rectosigmoid cancer patients after sphincter-saving surgery.     

Development, Validation, and Applicability of a Symptoms Questionnaire for Lactose Malabsorption Screening

Lactase deficiency has a high prevalence worldwide. Thus, a valid symptom scale would be a useful tool for identifying patients with lactose malabsorption. Objective To develop, validate, and apply a symptoms questionnaire on lactose malabsorption to identify lactose malabsorbers diagnosed with the gold-standard hydrogen breath test. Methods In the first part of the study, 292 patients completed a questionnaire at the end of a 50-g lactose breath test. The questionnaire included five items (diarrhea, abdominal cramping, vomiting, audible bowel sounds, and flatulence or gas) scored on a 10-cm visual analogue scale. In the second part of the study, 171 patients completed the questionnaire twice: first, according to their opinion when consuming dairy products at home and second, after a 50-g lactose breath test. Patients were grouped as absorbers or malabsorbers according to the result of the breath test. Results Diarrhea, abdominal cramping, and flatulence were scored significantly higher in malabsorbers than in absorbers. Total score of the symptomatic questionnaire was significantly higher in malabsorbers (17.5 versus 3.0, P < 0.01). According to receiver operator characteristics (ROC) analysis, the most discriminant cut-off of the total score to identify lactose malabsorption was 6.5 (sensitivity 0.75, specificity 0.67). In 58 malabsorbers the effect size of the questionnaire to determine sensitivity to change was 1.32. In the second part of the study, scoring of the home questionnaire was higher than after the lactose-breath test. The lactose malabsorbers rate was higher according to the home questionnaire than after the lactose breath test (72% versus 52%). The home questionnaire had excellent sensitivity (0.82) but low specificity (0.35). Conclusion We developed and validated a five-item symptoms questionnaire for lactose malabsorption. This is a valid test that permits patients with a total score lower than 7 to be excluded from future studies.