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Background: Successful bowel preparation is essential to an adequate performance of colonoscopy. Polyethylene glycol (PEG) with electrolyte solutions induces diarrhea with depletion of substrates fermentable by hydrogen (H)-producing colonic microbiota. Inulin has recently been suggested as a prebiotic substrate for the H breath test because it is resistant to intestinal hydrolysis and is fermented mostly by the colonic bacteria. This study aimed to assess time-dependent changes in H breath levels in order to predict the colonic preparation of patients scheduled for colonoscopy with or without oral supplementation of inulin. Methods: In this prospective nonrandomized trial, 127 subjects drank 4 l of PEG 280-mg solution as bowel preparation for colonoscopy. A subgroup of 31 patients also ingested inulin (10 g in 200 ml of water) at breakfast as an additional substrate to increase colonic H production. Measurements of H breath levels were performed immediately before and after colonic preparation. As the main outcome measure, the quality of the colonic preparation was scored as excellent to fair (i.e., clean bowel allowing successful pan-colonoscopy, including the terminal ileum) or poor (incomplete colonoscopy due to fecal debris). Results: The H breath levels decreased from 11.0 ± 1.8 ppm before PEG to 1.8 ± 0.3 ppm after PEG ( n = 18; P < 0.001). The H concentrations after PEG ingestion were significantly lower ( P < 0.001) in the patients with excellent-to-fair preparation than in the 19 patients with poor preparation. Ingestion of inulin induced an overall increase in H breath levels and improved discrimination between the patients with excellent-to-fair colonic preparation and those with poor preparation, leading to the sensitivity and specificity of such a test reaching 100 %. Conclusions: The H breath test with inulin ingestion can be a simple, noninvasive, reliable method for predicting successful colonic preparation that leads to cost savings and less patient discomfort/stress or need to repeat colonoscopy. [ABSTRACT FROM AUTHOR]

Dietary intolerances to fructose, fructans and FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) are common, yet poorly recognized and managed. Over the last decade, they have come to the forefront because of new knowledge on the mechanisms and treatment of these conditions. Patients with these problems often present with unexplained bloating, belching, distension, gas, abdominal pain, or diarrhea. Here, we have examined the most up-to-date research on these food-related intolerances, discussed controversies, and have provided some guidelines for the dietary management of these conditions. Breath testing for carbohydrate intolerance appears to be standardized and essential for the diagnosis and management of these conditions, especially in the Western population. While current research shows that the FODMAP diet may be effective in treating some patients with irritable bowel syndrome, additional research is needed to identify more foods items that are high in FODMAPs, and to assess the long-term efficacy and safety of dietary interventions. [ABSTRACT FROM AUTHOR]

Recent evidence suggests a role for enteric bacteria in the development of symptoms in subjects with irritable bowel syndrome (IBS). The concept was initially based on the common finding of an abnormal lactulose breath test to suggest the presence of small intestinal bacterial overgrowth (SIBO). Despite successful antibiotic studies based on these findings, the premise of bacterial overgrowth was met with skepticism due to the perceived inaccuracies of breath testing in humans. In this study, we conduct a systematic review and meta-analysis of the studies using breath testing in IBS subjects with comparison to healthy controls. A literature search was conducted to identify studies in which breath testing was conducted in subjects with IBS. Once abstract titles were identified, studies that examined breath testing in a case–control fashion were identified for paper review. After exclusion criteria were applied, the remaining papers were examined using meta-analysis, among which the prevalence of an abnormal breath test in IBS subjects was compared. Further analysis was conducted among studies with appropriate age- and sex-matched controls. Eleven studies met criteria for inclusion in the meta-analysis. Although heterogeneity was identified among studies on the basis of substrate used, lactulose was the most common substrate. In pooling the 11 studies, breath testing was more often abnormal among IBS subjects than health controls (OR = 4.46, 95% CI = 1.69–11.80). This was further evident in more appropriately designed age- and sex-matched studies (OR = 9.64, 95% CI = 4.26–21.82). The overall sensitivity and specificity for breath testing in separating IBS from healthy controls was 43.6 and 83.6%. This study demonstrates that the breath test findings in IBS appear to be valid. While this meta-analysis does not suggest that the breath test findings imply SIBO, the abnormal fermentation timing and dynamics of the breath test findings support a role for abnormal intestinal bacterial distribution in IBS. [ABSTRACT FROM AUTHOR]

Studies suggest that subjects with IBS have altered gut flora. Among these findings, methane production is more commonly associated with constipation-predominant symptoms. In this study, we prospectively evaluated the role of methane as a diagnostic test. Consecutive Rome I positive IBS patients referred for a lactulose breath test were eligible to participate. After exclusion criteria, subjects completed a symptom questionnaire grading bloating, diarrhea, and constipation on a VAS scale (0-100 mm). Once completed, a physician interviewed the subjects and rated the subject accordingly, and also determined whether the patient had C-IBS, D-IBS, or neither. Subjects and physicians were blinded to the results of the breath test. The presence of methane in the breath test was compared to the results of the scoring by subjects and physicians. A total of 56 Rome I positive IBS subjects were enrolled. During breath testing, 28 subjects produced methane. Good agreement between physician's evaluation and the patient's was seen (diarrhea = 0.69; constipation = 0.69; bloating = 0.62). The severity of constipation was noted to be greater in the methane group (49.3 +/- 28.7) than in the non-methane group (25.3 +/- 31.47) (P < 0.01). In contrast, diarrhea was less severe in the methane group (12.3 +/- 21.0) than the non-methane group (36.7 +/- 32.4) (P < 0.01). Out of the 56 patients, 23 C-IBS subjects were identified by the physician. When methane was used to predict the assignment of C-IBS compared to non-C-IBS, it had a sensitivity of 91.7% and a specificity of 81.3% (OR = 47.7, CI = 9.4-232, P < 0.00001). In conclusion, methane is a potential diagnostic test for the identification of C-IBS and may guide treatment. [ABSTRACT FROM AUTHOR]

Patients with cystic fibrosis (CF) have recently been deemed highly susceptible for bacterial intestinal overgrowth (BIO). We aimed to define the prevalence of BIO in children with CF by applying the H(2)-glucose breath test. Forty children with CF and ten healthy children received 1 g/kg D-glucose orally. Breath samples for H(2) content (ppm) were collected for 3 h. BIO was suspected if the breath hydrogen content increased by more than 20 ppm or if baseline concentrations topped 20 ppm. In 27 of 40 CF children (68%), breath hydrogen content exceeded 20 ppm. Whereas the breath hydrogen exhalation persisted above 20 ppm in almost all these children throughout the sampling period, none of the remaining children increased above this threshold. The high rate of CF children with elevated fasting hydrogen breath concentrations indicates that this phenomenon is less a sign of BIO rather than a consequence of global malabsorption and intestinal dysmotility. [ABSTRACT FROM AUTHOR]

The influence of the method alveolar air collection on measurements of trace gas concentration has received little attention. We measured the concentrations of H2, CH4, CO, and CO2 in sequential fractions of alveolar air collected with and without breath-holding. Without breath-holding, the concentration of these gases increased appreciably as increasing quantities of alveolar air were expelled. Twenty seconds of breath-holding markedly reduced this nonhomogeneity of alveolar air. Prediction of the excretion rate of trace gases from measurements of their concentration relative to CO2 and literature values for resting CO2 excretion underestimated the true excretion rate. We conclude that breath-holding prior to sample collection enhances the reproducibility of trace gas measurements. When calculating the rate of excretion of trace gases, the use of literature values for resting ventilation or CO2 excretion may result in appreciable underestimations of the true rate. [ABSTRACT FROM AUTHOR]

Purpose of Review: To critically review recent (past 3 years) literature on the definition, diagnosis, and management of small intestinal bacterial overgrowth (SIBO).Recent Findings: While various series continue to illustrate the occurrence of SIBO in disease states where well-known risk factors for its occurrence are present (hypochlorhydria, disorders of intestinal structure or motor function, pancreatic insufficiency, and chronic liver disease, for example), the current challenge is in defining the limits of SIBO. Is SIBO truly common among those with "functional" gastrointestinal symptoms where there is no evidence of maldigestion or malabsorption; the original hallmarks of SIBO? Our attempts to address this question continue to be hampered by the limitations of our diagnostic tool kit. There is hope—the application of modern molecular techniques to the study of the small intestinal microbiome, together with some innovative sampling techniques, such as real-time intestinal gas sampling, may soon allow us to truly define the spectrum of SIBO.Summary: SIBO, once removed from its original confines as a cause of malabsorption syndrome, has proven to be an elusive and moving target. Only the most rigorous studies employing validated methodologies will finally corral this mysterious entity. [ABSTRACT FROM AUTHOR]