Postgraduate Medicine

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Gaseous indigestion reviewing the record Albert I. Mendeloff To cite this article: Albert I. Mendeloff (1976) Gaseous indigestion reviewing the record, Postgraduate Medicine, 59:1, 193-199, DOI: 10.1080/00325481.1976.11716537 To link to this article: https://doi.org/10.1080/00325481.1976.11716537

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ipma an nais from the 60th interstate postgraduate medical assembly

• From the first few moments after birth until the last moment oflife, human beings have firsthand experience with air and gas in the gut. Attitudes about its presence, its noisy gurgling, its satisfying passage upward as a belch or downward as flatus, and the ability to relate these encounters to diet, emotions, or unusual exertions, undergo modifications as the individual is taught by eiders, learns from peers, or reinterprets personal experience. Gaseous indigestion is a condition complained ofby patients, not one found by pathologists. No one is exactly sure of its dimensions. A patient who seeks help for abdominal distress may occasionally also complain of gassiness or bloating, while other patients who are bothered principally by distention, borborygmi, or flatulence may later deny these symptoms and complain of right or le ft upper quadrant discomfort. Many persons are windy to all but them selves; others complain bitterly of a gassiness that is undetectable even by the physician trying to measure it. Since interpreting symptoms of indigestion is difficult for most physicians, and the condition has heretofore been the province of mystics or basic physiologists, neither patient nor physician usually benefits from an encounter which bas as its object the relief of gaseous symptoms. The purpose of this article is to review the status of knowledge about gastrointestinal gas and the relationship of gas to symptoms of gut dysfunction.

ga seo us indigestion reviewing the record Albert 1. Mendeloff, MD Sinaï Hospital of Baltimore

Patients who complain of gaseous indigestion may be more sensitive to an underlying intestinal motor abnormality than are others with similar dysfunction. Modifications in living and eating habits are bas.ic steps that can be taken to relieve the problem; drugs that alter intestinal activity or responses may be effective.

Sources of Gas

Gas gets into the gut either because it is swallowed as air or because it is generated within the gut by biochemical processes. Exogenous gas (swallowed air)-lngesting food or liquid without swallowing air is almost impossible. The food itself may contain as muchas 20% ofits weight as air (eg, an apple), or air may be beaten into it during preparation (eg, a milkshake, whipped cream). However, the actual amount of air ingested is almost al ways less than the amount contained in the food, since air tends to dissipate as the food is allowed to stand or as it is being eaten. The rapid drinking of carbonated beverages may be a major source of exogenous gas for those who depend on such rapid ingestion to provide relief from gassiness. The ensuing toPresented as the POSTGRADUATE MEDICINE Lecture.

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table 1. causes of aerophagia* Relief of dlscomfort Habituai, to relieve symptoms of peptic ulcer, hiatal hernia, gallbladder disease, angina pectoris, irritable colon syndrome Excessive swallowing of saliva associated with: Nausea arising from strong emotional reactions or psychic upsets, gastroduodenitis, pyloroduodenal irritability (psychogenic ulcer), biliary tract disorders Tension, anxiety, grief Postnasal drip

Faulty habits Eating rapidly, bolting or gulping liquids Excessive use of carbonated beverages, seltzers, beer Hypersalivation provoked by gum chewing, sucking on candy, excessive smoking, poorly fitting dentures Xerostomia from dehydration, mouth breathing, taking of anticholinergic drugs

Tics Repetitive sighing • Adapted from Roth and Bockus. 1

and-fro flow of air and gastric gas may actually increase the amount of gas remaining in the stomach after the beverage bas been finished. When not eating or drinking, we swallow air in saliva. Persons who chew gum or tobacco are constantly swallowing small amounts of air, and smokers also usually swallow air w hether or not they inhale smoke. Aerophagia, spasmodic swallowing of air followed by noisy eructations, is a complex phenomenon. Sorne ofits causes are outlined in table 1. Exhibitionistic belchers have learned to take large boluses of air into the esophagus and move most, but not ali, ofthis ingested air out in one dramatic high-decibe1 explosion. That controlling swallowed air is important in maintaining low gas volume in the upper gut is apparent from the success of treating small-bowel obstruction by placing an inlying nasogastric tube weil above the site of obstruction. Endogenous gas-It bas been clear for many

194

years that the colon is importantly involved in the manufacture of intestinal gas and that the· components produced in the colon are the main contributors to human flatus. Furthermore, it was early recognized that colonie flora play an important role in the manufacturing process and th at certain foodstuffs seem to favor or inhibit gas production. Several excellent recent reviews of this subject are available. 2 " 4 Volume of Gas

The human gut bad been thought to con tain at any one time about 1 liter of gas. Better investigatory techniques, including body plethysmography, infusion of argon into the colon to wash out the total volume of gas at the rectum, and comparison of abdominal x-ray films before and after instillation of known gas volumes into the gut, have led to the unanimous conclusion that the figure is closer to 100 ml. Recently, Lasser and colleagues, 5 in studies on 12 patients whose principal complaint was gaseous indigestion, conclusively demonstrated that the gut of · each of these patients also contained about 100 ml of gas. One may assume, then, that this figure is correct for ali persons who show no evidence of seriously compromised gut structure and function. Composition of Gas

Reports of analyses of gas composition have been available for the past century, but methodologie problems both in collecting the gas, ie, as gastric bubble or as flatus, and in analyzing it made the results difficult to assess. Because intestinal obstruction was such a pressing medical problem, many of the first reliable data on the composition of intestinal gas emerged from studies of this often lethal state and of treatment methods. The work of Wangensteen 6 and the concomitant development of the long small-intestinal tube were important advances during the 1930s. Most of the persons and experimental animais studied bad obstruction of the small intestine, and data on the gases recovered emphasized the.

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importance of swallowed air as its source. Statements such as "70% of ali intestinal gas originates as swallowed air'' appeared in textbooks. Thus, data on intestinal gas that were derived from studies of small-bowel disease were assumed to apply to ali gut gas. Gas chromatographie techniques now being used have been very helpful in discovering the exact composition of intestinal gas. There is little question that gas tric gas is composed of modified atmospheric air, with a nitrogen content of about 80% and an oxygen content of about 20%. Gas collected from the rectum or from a colostomy shows much more variation in composition, however, and it must represent a mixture of swallowed air, nitrogen and oxygen moving from blood to lumen, and hydrogen and methane thought to be generated in the colon from bacterial action on undigested substrates, principally carbohydrate. The terminal ileum, a well-known source of bicarbonate ion, probably contributes carbon dioxide (figure 1). Extensive documentation 2 supports the role of nondigestible carbohydrates as substrates for action by coliform or clostridial organisms in man. In healthy persons, these substrates are primarily the oligosaccharides of beans, ie, stachyose and raffinose, for which no hydrolytic enzyme exists in human small-bowel mucosa. In lactose-intolerant subjects, the lactose contained in milk is a superb gas former. Fortunately, its sensational potential for gas formation ( 1,400 ml from 2 gm lactose) is only 10% realized when these subjects are given lactose orally. Excessive loss of protein into the ileum and colon is not associated with much gas production, since intestinal bacteria are unable to liberate hydrogen from amino acids in appreciable quantities. Ninety-nine percent of the gases composing human flatus are nonodorous. The 1% that has an unpleasant odor consists of ammonia, hydrogen sulfide, indole, skatole, amines, and fatty acids. It is reasonable to suppose that these are metabolites generated by bacterial action on substrates reaching the colon.

As first demonstrated by Calloway, 2 the amount of hydrogen and methane produced by colonie bacteria can be determined by analyzing the breath, since a surprisingly constant proportion ofthese gases (for hydrogen, about 10% to 18%) appears in expired air. Breath analysis lends itself to a number of studie~. eg, transit times, digestibility of car-

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Figure 1. Sources of gastrointestinal gas. (From data of Calloway2 and Levitt and Bond.4)

Amount of gas asplrated from stomach

• •...C • •

•....c• ..........

Argon infused at constant rate produced

•

Patients More

Severe symptoms Patients 10 out of 12

Controls L.ess

Controls 1 out of 10 Changes in transit times Patients lncrease in 6 out of 10 Controls lncrease in sorne, decrease in. sorne

Composition and volume of rectal gases Patients No difference Controls No difference Figure 2. Comparison of results of argon infusion into normal subjects and into patients complaining of gassiness and irritable colon symptoms. (Adapted from Lasser and associates. 5 )

bohydrate polymers, the role of different foodstuffs as substrates for gas formation, and the effect of antibiotics in suppressing bacteria. Breath tes ting in clinical medicine bas a very promising future, and several reviews of the subject are now available. 7 • 8 In summary, new er work tends to refute the notion that intestinal gas is primarily composed of swallowed air. Careful quantitative recovery studies carried out by Calloway 2 and by Levitt and Bond 4 give results that can easily account for the nitrogen in flatus as

having diffused from blood into the gut lumen down a pressure gradient. The gradient is increased by rapid production of carbon dioxide, hydrogen, and methane in the colon. When flatulence was increased by bean ingestion, the concentration of nitrogen in flatus feil from 61% to only 19%. At least 10 ml of nitrogen per hour was recoverable in flatus. Since carbon dioxide, hydrogen, and methane diffuse from lumen to blood during the ir course through the colon, the actual volumes of these gases produced in sm ail bowel

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and colon are probably underestimated considerably from results of flatus analysis. Thus, the amount of nitrogen availab~e for diffusion into the gut from blood along the length of the gastrointestinal tract probably also is underestimated. It is important to understand that sudden changes in the volume of the stomach, as in atony after instrumental procedures such as catheterization or retrograde pyelography, cause nitrogen to diffuse from blood into the gastric lumen very rapidly until a new equilibration of partial pressure is reached. Intestinal Activity

Albert 1. Mendeloff

Dr. Mendeloff is physician-in-chief, Sinai Hospital of Baltimore, lnc., and professer of medicine, Johns Hopkins University School of Medicine, Baltimore.

tric function, however, that the ir role is to modulate the digestion and absorption of food so as to make these processes unnoticeable by most persons.

In patients who complain of a variety of symptoms related to the small and large bowel, a disorder of coordinated motor function seems to be the predominant cause. Coordination of gastric emptying with receptive relaxation of the duodenum is necessary if the gastric contents are to leave the stomach; such coordination results from the basic electrical activity of the two adjacent hollow organs. Once chyme strikes the duodenal mucosa, hormones are generated; thus far it seems that cholecystokinin and gastrin have important modifying effects on the activity of the small bowel distal to the duodenum and on the activity of the right colon as weil. In fact, recent evidence suggests that the hallowed gastrocolic and gastroileal reflexes can be initiated by cholecystokinin within four minutes after an intravenous injection of this hormone. Cineradiographic techniques have shown that such injections cause the duodenum to become hypotonie for a few minutes (to allow bile and pancreatic juice to flow into it?); the jejunum and ileum begin to contract actively severa! minutes later, as if to increase vill us activity and surface contact needed for proper digestion and absorption. The role of vasoconstrictive intestinal serotonin and vasoactive intestinal peptide (from the pancreas) in coordinating these peristaltic contractions is not clear, nor is the role of tone due to vag al action. It is a safe assumption from what bas been learned about motor and secretory gas-

Of what, then, do patients complain when they say that they have indigestion? Splanchnic nerve receptors are not adequate to allow a precise definition of these unpleasant sensations. The resulting imprecision and the rather cumbersome methods developed to study disordered intestinal activity do not permit the physician to fully appreciate the problem that patients try to describe. It is no wonder that patients regard gassiness as a part of the malfunction rather th an as a result of underlying motor abnormality or of attempts to relieve discomfort. Thus, gas may be blamed for the problem and the physician, having no better cul prit to indict, may go along with the patient and commiserate about gassiness as if nothing could be do ne about it. The results of ali studies of patients with irritable colon syndrome, ie, stools alternating between sm ali, hard scy baia and loose, wet globs, pain or discomfort in ali qlladrants of the abdomen, and generally normal findings on laboratory and physical examination, tend to show that over the years, regardless of treatment, symptoms persist but patients learn to live with them. That symptoms usually correlate with persona! stresses and socioeconomic vicissitudes is much easier to demonstrate in these patients than, for example, in patients with ulcerative colitis. 9 .,..

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Appreciation of the Problem

table 2. suggestions for patients with gaseous indigestion Do not smoke before meals Allow more time for meals; chew slowty Drink slowty and do not talk while drinking Avoid carbonated drinks, milkshakes, chiffon pies

Do not chew gum lncrease dietary bulk but avoid beans, cabbage, milk in fluid form

table 3. suggestions for patients with irritable colon syndrome Try to eat three meals a day, seated Arise ear1y enough to get sorne exercise before breakfast Eat a uniform or standard breakfast consisting of fruit, high fiber cereal, and skim milk (if tolerated), plus coffee or tea* Try to allow 30 minutes after breakfast to have a bowel movement* Take 45 minutes or longer for lunch; eat and drink slowty On retuming home at end of work day, or during afternoon if at home, put feet up for 20 to 30 minutes Obey urge to defecate within one hour of any meal and before going to bed; do not sit on commode longer than ten minutes each time Enjoy weekends-eat leisurely meals and get planty of exercise *If these goals cannot be achieved because of unalterable occupational demands, it is better to avoid breakfast completely and have a late evening meal followed by an attempt to defecate.

table 4. types of drugs which have been used for treatment of gastrolntestinal complaints Indigestion, gas, or both

Irritable colon syndrome

Both types of complalnt

Drugs that increase intestinal activity, eg, metoclopramide hydrochloride, ethanechol chloride

Drugs that reduce intestinal activity, eg, anticholinergic or musculotropic agents

Drugs that alter intestinal responses, eg, cyproheptadine hydrochloride

Broad-spectrum antibiotics (one week 1 each month)

Mild sedatives

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Hydrophilic colloid laxatives (every other day)

Management of the Gaseous Patient

If a patient complains of upper gastrointestinal distress or of irritable colon syndrome, the physician usually responds with a complete physical examination, laboratory studies, and radiologie explorations. Once satisfied that there is no underlying disease, the physician attempts to discover why the patient is more sensitive to disordered motor activity than are others who probably have similar dysfunction. (As Lasser and coworkers5 recently pointed out, the fact that gaseous subjects are more sensitive to distention of the gut than are control subjects has been appreciated for many years, as has the fact that the patients who complain the most do not show increased amounts of gas on abdominal radiographs.) If the patient also complains of gassiness, most physicians are baffled. A gastric air bubble is usually present in ali persons except those with achalasia or a neoplastic obstruction at the cardioesophageal junction. A flat abdominal x-ray film is thus an important first step in the workup of those who complain of gassiness. One not only looks at the size and position of the air bubble but searches for other accumulations of gas, especially in the splenic flexure of the colon. None of the previously mentioned, recently unearthed facts about intestinal gas seem at first to offer the physician much help in dealing with gaseous patients. But this may not be true. Lasser and colleagues 5 have recently reported applying the ir gas washout technique to studies of patients complaining of gassiness and irritable colon symptoms. Their results, shown in figure 2, are of great interest. Prominent findings were that gassy patients ( 1) bad no more gas in the bowel th an control subjects and (2) were very uncomfortable when argon was infused into the intestine at a constant rate that produced little or no discomfort in control subjects; in six patients symptoms were so severe that the study bad to be terminated. Closer analysis seemed to demonstrate that in symptomatic patients the infused gas did not move forward at a normal rate. Half of the patients passed so little gas during infusion

POSTGRADUATE MEDICINE • January 1976 • Vol. 59 • No. 1

th at washout curves could not be constructed, indicating a motor defect in the distal movement of gas. Not only did gas not move distally, but an appreciable amount refluxed into the stomach, perhaps indicating sorne defect in pyloric function. The composition of gas in flatus of controls and patients was identical. Wh at can be done forthese patients? Tables 2 and 3 summarize suggestions that physicians can make to their patients with gastrointestinal complaints to help them help themselves. Table 4 indicates types of drugs th~t are currently being used to treat these patients. In view of the slowed transit time of intestinal gas demonstrated by Lasser and coworkers, 5 it is not surprising that drugs tending to decrease intestinal contractility are not very effective. New drugs that increase sensitivity either to vagal impulses orto hormonal agents, thereby increasing peristaltic forces and inhibiting stretching of pain receptors by

normal volumes of gas in sensitive subjects, should be sought. Much progress can be achieved in making the lot of these patients more bearable, and 1 believe the use of new drugs is the key to such progress. Summary

Gaseous indigestion is a puzzling phenomenon. The affected person cannot exactly define the unpleasant sensations experienced, and methods of studying intestinal activity are cumbersome and imprecise. The basic abnormality seems to be an incoordination in intestinal motor function, with slowed transit time for gas. Drugs that increase peristaltic forces and inhibit stretching of pain receptors by normal volumes of gas may prove effective in treating these patients. • Address reprint requests to Albert 1. Mendeloff, MD, Department of Medicine, Sinaï Hospital of Baltimore, Inc, Belvedere Ave at Greenspring, Baltimore, MD 21215.

R~ferences

c

1. Roth JL, Bockus HL: Aerophagia: lts etiology, syndromes, and management. Med Clin North Am, Nov 1957,pp 1673-1696 2. Calloway DH: Gas in the alimentary canal. In Code CF, Heidel W (Editors): Handbook of Physiology, Section 6: Alimentary Canal. Baltimore, Williams and Wilkins, 1968, vol 5, ch 137 3. Askevold F: Investigations on the influence of diet on the quantity and composition of intestinal gas in humans. Scand J Clin Lab Invest 8:87-94, 1956 4. Levitt MD, Bond JH Jr: Volume, composition, and source of intestinal gas. Gastroenterology 59:921-929, 1970

5. Lasser RB, Bond JH Jr, Levitt MD: The role of intestinal gàs in functional abdominal pain. N Engl J Med 293:524526, 1975 6. Wangesteen OH: Intestinal Obstructions. Springfield, Dl, Charles C Thomas, 1945 7. Newman A: Breath-analysis tests in gastroenterology. Out 15:308-323, 1974 8. Hepner GW: Breath analysis: Gastroenterological applications. Gastroenterology 67:1250-1256, 1974 9. Mendeloff Al, Monk M, Siegel Cl, et al: IUness experience and life stresses in patients with irritable colon and with ulcerative colitis. N Engl J Med 282:14-17, 1970

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