“Breath testing represents an important, simple, and safe test to diagnose carbohydrate maldigestion syndromes and small intestinal bacterial overgrowth (SIBO).”

Originally Published By:

Rezaie A, Buresi M, Lembo A, et al. Am J Gastroenterol. 2017 May; 112(5): 775-784.

 

Participants
Ali Rezaie, MD, MSc, FRCP(C), Michelle Buresi, MD, Anthony Lembo, MD, Henry Lin, MD, Richard McCallum, MD,
Satish Rao, MD, Max Schmulson, MD, Miguel Valdovinos, MD, Salam Zakko, MD, Mark Pimentel, MD

Current State of Breath Testing

  • Breath tests (BTs) are important for the diagnosis of carbohydrate maldigestion syndromes and small intestinal bacterial overgrowth (SIBO)
  • Principal gases used in clinical breath testing, hydrogen (H2) and methane (CH4), are both produced via microbial fermentation in the gut
  • Practitioners are currently using various substrates and doses for a range of indications
  • Previously there was no North American consensus on the utility of breath testing and no standardized indications for testing, test methodology or interpretation of results

Objectives & Methodology

  • Consensus meeting of experts convened to develop guidelines for clinicians and researchers
  • Pre-meeting survey (17 clinician-scientists) and meeting (10 in attendance) focused on five domains:
    1. Indications
    2. Preparation
    3. Performance
    4. Interpretation of Results
    5. Knowledge Gaps

Results*

Consensus achieved on 26 out of 28 statements for each of the five broad domains:

Interpretation % Agree Quality of
Evidence (Grade)
Recommend antibiotics should be avoided for 4 weeks prior to the breath test Agree (88.9%) High
A firm position statement cannot be reached due to lack of conclusive data on stopping or continuing pro/prebiotics prior to breath testing Uncertain (44.4%) Very Low
Suggest that, if tolerated by the patient, promotility drugs and laxatives should be stopped at least 1 week prior to breath testing Agree (77.8%) Very Low
Suggest that fermentable foods such as complex carbohydrates should be avoided on the day prior to breath testing Agree (100%) Moderate
Suggest that the fasting period for breath testing as part of preparation should be 8-12 hours
Agree (77.8%) Low
Recommend that smoking should be avoided on the day of breath testing Agree (100%) High
Recommend that physical activity should be limited during breath testing Agree (100%) High
Suggest it is not necessary to stop proton pump inhibitors prior to breath testing Agree (77.8%) Low

*Strength of recommendation was assigned either strong “Recommend” or weak “Suggest”. The strength of each statement is based on resource and cost benefit, patients’ values, risk/benefit and quality of evidence. Quality is rated as high, moderate, low or very low.

Interpretation % Agree Quality of
Evidence (Grade)
Current small bowel techniques are not satisfactory for the assessment of SIBO Agree (88.9%) Low
If culture is considered for diagnosis of SIBO, based on the current evidence, suggest the threshold of >103 c.f.u./ml for the definition of SIBO Uncertain (44.4%) Low
Suggest breath testing in the diagnosis of SIBO Agree (100%) Moderate
Until a true gold standard is established, suggest breath testing in assessing the presence of antibiotic-responsive microbial colonization of the gastrointestinal tract Agree (77.8%) Moderate
Suggest to evaluate for excessive methane excretion on breath test in association with clinical constipation and slowing of gastrointestinal transit Agree (88.9%) Moderate
Suggest that breath testing should not be used for assessment of orocecal transit time Agree (77.8%) Moderate
Suggest breath testing for the diagnosis of carbohydrate maldigestion syndromes Agree (88.9%) Moderate
Suggest breath testing in the assessment of conditions with bloating Agree (88.9%) Low

“Glucose and lactulose breath tests remain the least invasive alternatives to diagnose SIBO”

Interpretation % Agree Quality of
Evidence (Grade)
Suggest that the correct dose of lactulose for breath testing is 10g with or followed by one cup of water Agree (100%) Moderate
Suggest that the correct dose of glucose for breath testing is 75g mixed with or followed by one cup of water Agree (88.9%) Low
Suggest that the correct dose of lactose for breath testing is 25g mixed with or followed by one cup of water Agree (88.9%) Low
Suggest that the correct dose of fructose for breath testing is 25g mixed with or followed by one cup of water Agree (88.9%) Moderate
Suggest that fructose and lactose breath testing should be performed for at least 3 hours Agree (100%) Moderate
Suggest that the presence of bacterial overgrowth should be ruled out before performing lactose or fructose breath testing Agree (100%) Moderate
Recommend that hydrogen, methane and carbon dioxide should all be measured simultaneously during breath testing Agree (77.8%) High

“Overall, given the importance of methane in association with GI symptoms and the interaction of methane with hydrogen production, measurement of methane should be integrated in all breath tests”

Interpretation % Agree Quality of
Evidence (Grade)
Suggest that a rise of > 20 ppm from baseline in hydrogen during the test should be considered positive for fructose and lactose breath testing Agree (100%) Low
Suggest that until better data are available, for clinical and< research purposes, a rise of > 20 ppm from baseline in hydrogen by 90 minutes should be considered postive test for SIBO Agree (77.8%) Low
Suggest that two peaks on breath test are not required for diagnosis of SIBO Agree (88.9%) Low
Until further data is available, suggest that a level of 10 > ppm be considered positive for methane on a breath test Agree (88.9%) Low
A firm position statement cannot be reached due to lack of conclusive data on the definition of abnormal methane on to be > 3 ppm Uncertain (44.4%) Low

Consensus Outcome

  • Consensus doses for lactulose, glucose, fructose, and lactose breath tests are 10g, 75g, 25g, and 25g respectively
  • Breath testing is useful in the diagnosis of carbohydrate maldigestion and methane-associated
  • For glucose or lactulose breath tests for SIBO, a ≥ 20 ppm rise in hydrogen by 90 minutes is considered positive
  • For assessment of carbohydrate maldigestion, a rise in hydrogen of ≥ 20 ppm above baseline during breath testing is considered positive

“Breath testing remains a useful diagnostic tool for patients with unexplained IBS-like symptoms including gas and bloating as well as diarrhea or constipation”

For more information, the full article can be accessed online via The American Journal of Gastroenterology.