Bloating and functional gastro-intestinal disorders: Where are we and where are we going?

Figure 1 Possible underlining mechanism behind bloating.

Figure 2 Gas physiology in the gastrointestinal tract. Gas input is determined by swallowing, chemical reactions (bacterial fermentation, food digestion) and diffusion from blood stream. Output is achieved by belching, absorption into the blood, bacterial consumption and anal evacuation. Adapted from[31].

Figure 3 Gas challenge test. The method consists in the infusion of a mixture of gases in the jejunum while anal gas output is quantified. Adapted from[65].

Figure 4 Altered intra-abdominal volume displacement as possible explanation of bloating. Bloating patients show an impaired abdomino-phrenic coordination with a paradoxical contraction of the diaphragm coupled with a relaxation of the abdominal wall leading to a modification in abdominal girth. Adapted from[129].