Measurement of pulmonary hydrogen (H2) and H2 diffusion from the small bowel and the colon.

An accurate, relatively simple gas-solid chromatographic method for determination of breath H2 is described. Three different end-expiratory breath sampling techniques were evaluated. Changes in ventilatory activity was found to be the main cause of inaccuracies in end-expiratory breath H2 determinations. Pulmonary H2 excretion was measured after instillations of H2 in jejunum and colon. H2 excretion during the first 30 min after instillation was approximately seven times greater from the jejunum than from the colon. Marked individual variability was noted, and it is suggested that this may be explained by variations in intestinal peristaltic activity, which must be of importance in the process of H2 diffusion from gut lumen. It is further suggested that the H2 breath test should be regarded as a semi-quantitative test for intestinal H2 formation.