Assessment of Orocoecal Transit Time by Means of a Hydrogen (H2) Breath Test as Compared with a Radiologic Control Method

Abstract

The definition of the orocoecal transit time by means of the hydrogen (H₂) breath test is not unequivocal. In this study the orocoecal transit time as measured with an H₂ breath test was compared with that obtained with a radiologic method. Two definitions of orocoecal transit time by the H₂ breath test were evaluated: A) the time from eating to the first of three consecutively rising H₂ values, and B) the interval to H₂ values 50% above ‘small-bowel level’. Transit times measured in accordance with both definitions were closely correlated to that obtained with the radiologic method (A, r = 0.84; B, r = 0.90; for both, p < 0.001), but transit time measured by definition A gave shorter values than the radiologic method (p < 0.05). The mean transit time in patients with constipation was significantly longer than that in normal subjects and patients with functional diarrhoea (p < 0.05). There was a significant correlation between the difference in transit time measured with the H₂ breath test and the radiologic method and the transit time measured by the control method. This may indicate that rapid transit is associated with a delayed ‘colonic’ rise in H₂ levels and slow transit with an early H₂ rise.