Final Hydrogen Breath Testing in GI Disorders

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Hydrogen Breath Testing in GI Disorders : 

Hydrogen Breath Testing in GI Disorders Dr. Ajesh Bansal Gastroenterology

Introduction : 

Introduction Hydrogen breath tests are based on the fact that there is no source for hydrogen gas in humans other than bacterial metabolism of carbohydrates So, the hydrogen breath test depends on the presence of hydrogen producing bacteria. Gut 2006;55:297–303

Introduction : 

Introduction Hydrogen gas is produced at a rate of 4 L for every 12.5 g of undigested carbohydrate. Hydrogen is also consumed by bacteria, especially methanogens. Approximately 20% of all hydrogen ingested or produced is eliminated via the lungs; the rest is either consumed or expelled via the rectum AJG – Vol. 97, No. 5, 2002

Introduction : 

Introduction Approximately 15% of patients are methane producers. Colonic pH is important as acidic milieu inhibits bacterial activity. One can deal with these problems by measuring breath methane along with breath hydrogen, or by repeating the test after pretreatment with magnesium sulfate in so-called flat hydrogen breath tests J Clin Invest 1991;67:643. Gastroenterology 1986;90:1682

Normal Intestinal Gas Dynamics : 

Normal Intestinal Gas Dynamics Intestinal gas is balance of four dynamic processes: 1) swallowing and eructation (burping), 2) production and consumption of gases by luminal bacteria, 3) absorption through gut mucosa and elimination through the lungs, and 4) expulsion from the rectum (flatulence).

Intestinal Gas : 

Intestinal Gas Oxygen and nitrogen are the predominant gases in swallowed air, and these gases diffuse freely across the gastric mucosa. Bicarbonate secreted by the pancreas reacts with protons from gastric acid, forming carbon dioxide, which is absorbed and ultimately eliminated through the lungs.

Intestinal Gas : 

Intestinal Gas Thereafter, there is no other gas production until a nonabsorbable but fermentable substrate, such as lactulose, sorbitol, or, in some people, malabsorbed lactose or fructose, reaches colon

INTESTINAL GAS : 

INTESTINAL GAS The bacteria then break down the substrate to hydrogen, carbon dioxide, and trace gases. The hydrogen is then either absorbed by diffusion or consumed by other bacteria to reduce carbon dioxide to methane or acetate and reduce sulfates to sulfides.

Clinical Applications : 

Clinical Applications Lactase Deficiency Fructose deficiency Small Bacterial Overgrowth. Oral Caecal Transit time

Lactose Intolerance : 

Lactose Intolerance Lactose intolerance is the most common disaccharidase deficiency. Symptoms of bloating, pain, and/or diarrhea often indistinguishable from functional bowel syndromes. N Engl J Med 1975;293:1232.

Principle : 

Principle The premise underlying the lactose breath test is that patients lacking lactase activity, the lactose remains in the small bowel and eventually reaches the colon. The bacteria ferment the lactose, producing hydrogen, which is then absorbed and eliminated through the lungs.

Slide 13: 

The hydrogen breath test, using 50 g of lactose, has been found in a study to have a sensitivity and specificity of 100% 50-g dose crticised as amount is far more than an individual usually ingests at one time. N Engl J Med 1975;293:1232.

Slide 14: 

The usual dose used is 10–12 g, but doses of 25–50 g, as suggested by Rana et al. may be more sensitive Rana S, Bhasin DK, Gupta D, Mehta SK. Indian J Gastroenterol 1995;14:13–4.

Slide 15: 

The lactose breath test represents a noninvasive, reliable way of determining lactase status in irritable bowel syndrome, recurrent abdominal pain of childhood, or patients with other nonspecific GI symptoms. N Engl J Med 1975;292: 1156–9.

Lactose H2 test : 

Lactose H2 test However, the importance of lactase deficiency and the therapy there of in functional bowel syndromes with average lactose loads (20 g) remains unclear.

SIBO : 

SIBO Bacterial overgrowth can present steatorrhea (from bile acid deconjugation), macrocytic anemia (low serum vitamin B12, high red cell folate), patchy small bowel lesions with villous blunting, and nonspecific chronic diarrhea and/or bloating.

Slide 18: 

The gold standard, is jejunal fluid culture. Obtained by intubating the jejunum under fluoroscopy with a closed-tube system using a capsule for anaerobic collection. 106 colony-forming units/ml is abnormal

SIBO : 

SIBO The bacterial overgrowth syndrome can occur as a result of changes in gastric acid (e.g., postgastrectomy) or delayed intestinal transit (e.g., diabetes, scleroderma, surgical blind loops) or with surgical loss of the ileocecal valve chronic pancreatitis and exocrine insufficiency Cystic Fibrosis Celiac disease Elderly

PRINCIPLE : 

PRINCIPLE Due to the presence of bacteria in the small intestine the carbohydrates will be fermented early in the small intestine producing an early peak in the breath Hydrogen or CO 2 Gut 2006;55:297–303.

Fructose Intolerance : 

Fructose Intolerance Fructose malabsorption, results in diarrhea and/or bloating after sucrose (broken down to glucose and fructose) ingestion or fruit intake. Related to abnormalities in the expression of GLUT5, a specific fructose transporter Abnormal breath testing has been seen in 44–100% of young children, depending on the dose of substrate used. Eur J Pediatr 1995;154:362–4.

Oral Caecal Transit time : 

Oral Caecal Transit time Lactulose passes unabsorbed through the small bowel and into the colon. Therefore, apart from detecting SIBO, it can also be used as a measure of orocaecal transit Normally 90 minutes

Breath test? : 

Breath test? As they are simple and noninvasive, and reasonably accurate, breath tests are important in unexplained steatorrhea and malabsorption, nonspecific symptoms where jejunal fluid testing would be too cumbersome

Breath Testing Preparation : 

Breath Testing Preparation As hydrogen production is normal phenomenon patient preparation is vital to a successful and accurate hydrogen breath test. Patients are instructed to avoid unfermentable carbohydrates (pasta, breads, fibre cereals) the night before the test. Since rice is readily absorbed, a meal of rice and meat, without other carbohydrates (unless made with rice flour), is generally what is recommended.

Preparation : 

Preparation Avoid Smoking (< 2hr before testing) Avoid excercise (< 2hr before testing) An antibacterial mouth rinse before testing prevents premature hydrogen or carbon dioxide production from the action of oral flora on the test substrate

Preparation : 

Preparation If testing for lactose intolerance, one should consider recommending an avoidance of lactose for 1–2 wk prior to test. No antibiotics or antidiarrhoeals use since last one month

Interpretation : 

Interpretation End-expiratory hydrogen is measured by gas chromatography at baseline and at 30-min intervals after the test meal. Portable breath hydrogen analyzers have also been developed and perform well.

Interpretation : 

Interpretation Studies using a 20 ppm increase from baseline as a cutoff were found to lack sensitivity, whereas increases of 10 ppm, on two consecutive measures, boast a higher sensitivity without greatly diminishing specificity Gastroenterology 1993;105:1404.

Interpretation : 

Interpretation The length of time over which measurements should be taken is controversial. It has been shown that increasing the length of the test from 4 to 8 hrs increases test sensitivity, by capturing a few patients with very slow transit

Interpretation : 

Interpretation Even in the absence of a significant rise, fasting breath hydrogen levels of 20 ppm or more are also considered “positive” and occur in up to one third of cases Higher levels achieved because of the bacterial overgrowth acting on the previous normal meal and that these have taken longer to return to baseline by the presence of slow transit and delayed presentation of that meal to the bacterial colony

Slide 31: 

In a study, 11 of 27 patients with bacterial overgrowth had fasting levels more than 20 ppm and seven of 27 measured 30 ppm. Fasting breath hydrogens have been found to be a very frequent feature of untreated celiac disease (58.8%). Gastroenterology 1988;95:982–8. Gastroenterology 1987;93:53–8.

Slide 32: 

A study of 200 healthy subjects showed that the average fasting breath hydrogen was 7.1 ± 5 ppm, all patients were under 42 ppm, and 1% had 30 ppm Gastroenterology 1984;87:1358.

Slide 33: 

Abnormal glucose hydrogen breath test

Lactulose breath test : 

Lactulose breath test Unabsorbed fermentable substrates (e.g., lactulose) yield colonic peaks at 2–3 h into the test and are usually more than 20 ppm over the baseline, whereas peaks associated with small bowel bacterial overgrowth occur within 1 h and are less prominent.

Lactulose breath test : 

Lactulose breath test All patients should have a colonic peak with lactulose Completely “flat” responses to lactulose imply altered flora (from antibiotics or acidic pH) extremely slow transit methane producer

Slide 36: 

Unlike the lactose, glucose, and fructose tests, a rise is expected with lactulose, so one must attempt to differentiate the later and taller colonic peak from the small bowel peak that occurs with bacterial overgrowth. Interinterpreter reliability of lactulose breath tests is lower than with glucose, as are the sensitivity (68%) and specificity (44%)

Glucose Hydrogen Breath test : 

Glucose Hydrogen Breath test The fact that any peak is abnormal is the main advantage in terms of the interpretation of tests using glucose over those using nonabsorbable substrates such as lactulose. With the latter, one must consider the timing and amplitude of the peak(s) (small bowel vs colon), and this reduces the interobserver agreement from a value of 1.0 (with glucose) to 0.86.

Slide 40: 

The usual dose range used in the literature has been 50–80 g, and the sensitivity and specificity are 62% and 83%, respectively

Lactose Hydrogen Breath test : 

Lactose Hydrogen Breath test Complicating the interpretation of lactose tests for overgrowth is that, in addition, patients with lactase deficiency will also produce hydrogen from the unabsorbed lactose as it passes into the colon. However, the peak in lactase deficiency will be delayed (colonic peak) and more prominent than that seen with overgrowth (small bowel peak)

D-Xylsoe Breath test : 

D-Xylsoe Breath test Xylose, given in a dose of 1 g, is absorbed entirely in the proximal small bowel and is metabolized minimally . Xylose is predominantly catabolized by gram negatives and, as such, is an excellent substrate for the purposes of breath testing for bacterial overgrowth . Gastroenterology 1984;86:174. J Clin Gastroenterol 1999;29:143–50.

Slide 44: 

The xylose breath test seems to have a better performance than the tests performed using glucose, lactulose, or bile acids It had a 95% sensitivity and a 100% specificity in one study (107), for diagnosing bacterial overgrowth. Indian J Med Res 1984;80:598–600. Scand J Gastroenterol 1985;20:1267.

Slide 45: 

The stable radioistope (13C) xylose breath test as well as a 15-g xylose hydrogen breath test , have been used for identifying bacterial overgrowth in children. J Pediatr Gastroenterol Nutr 1997;25:153–8.

Indian data : 

Indian data Predominant methane producers (>10ppm) affects lactose hydrogen breath tests in 6.49 - 20.14% of subjects Rana SV, Sinha SK, Sharma S, Kaur H, Bhasin DK, Singh K. Dig Dis Sci. 2009 Jul;54(7):1550-4.

Slide 47: 

Prevalence of SIBO in IBS from North India is approximately 11.1%, which is lower than the reported prevalence Trop Gastroenterol. 2008 Jan-Mar;29(1):23-5

Slide 48: 

74% patients with Giardia lamblia and (44.4%) controls showed lactose maldigestion. In conclusion, frequency of lactose maldigestion is significantly higher in adult Indians suffering from Giardia lamblia infection compared to healthy individuals. Dig Dis Sci. 2005 Feb;50(2):259-61.

Slide 49: 

78.0 % subjects passing E. histolytica cysts had lactose malabsorption compared with (42.5 %) controls In conclusion, that lactose malabsorption is significantly more common in individuals infected with E. histolytica and passing cysts compared with control subjects. Br J Nutr. 2004 Aug;92(2):207-8.

Summary : 

Summary

Conclusions : 

Conclusions They are noninvasive and exploit normal physiological principles of intestinal gas dynamics and the action of bacteria on different substrates Breath tests are also useful in the workup of nonspecific bloating and diarrhea, vitamin B12 deficiency, postsurgical syndromes, and steatorrhea.

Conclusion : 

Conclusion Although the test performances vary from study to study, hydrogen breath testing appears to be the accurate for the detection of bacterial overgrowth, and lactose breath testing can accurately confirm or rule out lactase deficiency.

Slide 53: 

The breath tests for pancreatic and liver disease are not yet sufficiently studied or refined to be recommended routinely. Adequate test preparation is critical. Breath tests, in general, are underutilized modes of investigation for a variety of GI disorders and provide excellent opportunities to demonstrate normal and abnormal intestinal gas physiology

Slide 54: 

THANKS

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