Methodological aspects of breath hydrogen (H₂) analysis. Evaluation of a H₂ monitor and interpretation of the breath H₂ test

Abstract

The reliability of end-expiratory hydrogen (H₂) breath tests were assessed and the significance of some important pitfalls were studied, using a compact, rapid H₂-monitor with electrochemical cells. The H₂ response was shown to be linear and stable. The reproducibility of the breath collection technique was determined in 20 patients following ingestion of lactulose. The increment between consecutive means of duplicate samples indicative of a significant rise of H₂ concentration never exceeded 10 p.p.m., the mean coefficient of variation of the duplicate samples was below 5%. Fasting H₂ levels were studied in 10 healthy adults during a 4-month period and they showed very marked inter- and intra-individual variability (16% above 40 p.p.m.). Initial peaks (early, shortlived H₂ rises unrelated to carbohydrate malabsorption) were identified in 25% of the breath tests (in 4% above 20 p.p.m.). It is concluded that the technique used for interval sampling of end-expiratory breath samples for H₂ concentration gives reliable results. The biological significance of H₂ concentration increments can only be evaluated if the limitations of the technical procedures and the individual ability to produce H₂ is known.

Key words:

• breath tests
• carbohydrates
• hydrogen
• intestinal absorption
• malabsorption