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Flatulence

Pathophysiology

The principal gases in flatus are CO₂ , methane and hydrogen. Nitrogen and oxygen are present in flatus and are derived from swallowed air. Bacterial fermentation of nonabsorbed carbohydrate such as beans results in considerable colonic generation of H₂ and CO₂ . Lactase deficiency is another common cause of flatulence because the unabsorbed lactose is metabolized in the colon to short-chain fatty acids, H₂ , and CO₂ . Approximately 14% of H₂ produced in the colon is absorbed and excreted in the breath. Measurements of breath H₂ permit the detection of lactase deficiency by measuring breath H₂ content bloating.

Clinical Features

Patients may complain of excessive gas passages and foul odor. It often is helpful to quantify the frequency of gas passages before initiating diagnostic studies because patients have nothing with which they can compare their experience. Levitt et al reported that healthy young men have 13.6 + 5.6 gas passages per day. The patient should be advised to keep a flatus diary, noting when each passage occurs.

Diagnostic Studies

Excess flatulence can be treated empirically. Associated symptoms such as crampy discomfort and change in bowel habits, however, should prompt consideration of stool examinations for parasites.

Management of Excess Flatulence

The diet should be reviewed to identify foods that may increase gastric gas accumulation and intestinal gas generation. The foods and mechanisms that exacerbate belching, such as drinking carbonated

Carbohydrates that are absorbed poorly in the small bowel and thus lead to increased gas production (H₂ and CO₂ ) in the colon should be identified. These include broccoli, cabbage, and Brussels sprouts.

If flatulence does not respond to these measures, an addition diet may be tried. A small number of safe foods should be given, and a determination made whether improvement occurs. One new food then is added every 48 hours in an effort to determine which food or food groups is poorly tolerated.

It is difficult to substantiate the advertised claims for the effectiveness of various antiflatulence agents. Simethicone, as a single agent or combined with other products, has not been proven to reduce.