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home - Miscellaneous - Other - Gas Written by Dr Sebastian Zeki

Defines the pathophysiology of fluid and nutrient malabsorption,
including causes, e.g. anatomical and functional short bowel
syndrome, high output stomas, enterocutaneous fistulae and
pancreatic insufficiency

Knows how to investigate patients with malabsorption
Describes the clinical consequences of malabsorption, including
malnutrition, fluid and electrolyte disturbance and micronutrient
deficiency and anaemia and how to manage these

Describes all other causes of anaemia, including bone marrow
disorders and haemolysis

Describes the metabolism, absorption and bioavailability of iron, B12
and folate and clinical conditions and diets associated with their

Identifies and appropriately investigates clinical features suggestive of

Manages fluid, electrolyte and micronutrient disturbances associated
with short bowel syndrome or high output stomas

Uses the appropriate investigations for the different types of anaemia
Takes a careful clinical approach to managing patients with
malabsorption and anaemia. Explains plan of management clearly to
patients and their relatives.



Knows the different causes of enteric dysmotility (myopathy and
neuropathy) and their presenting features

Have a knowledge of scleroderma amyloid and congenital motor
abnormalities of the gut that affect absorption

Knows the principles of investigation pain relief and prokinetic drug

Understands bacterial overgrowth and its treatment
Understands how emotional status can affect gut function
Knows how diabetic complications can affect the gut
Can determine when organic obstruction is occurring TO
Can understand the principles and interpret the results of
gastrointestinal motility investigations (including manometry transit
studies etc) and autonomic function tests
Advises on appropriate prokinetic drugs and analgesics
Can detect and treat bacterial overgrowth
Advises on appropriate surgery including bypass procedures
Can relieve symptoms while not causing/risking harm with other
medications (e g opiates)

Works with the multidisciplinary NST psychiatrists/psychologists
surgeons and the pain management team

Can give careful explanation of the problems to the patient carers
friends and family


Intraluminal production3 of the 5principal gases, CO2, H2, and CH4, are produced within the bowel lumen. Sources of Gas Production Gas + Burping [O2] Air swallowingAir swallowing is the major source of stom-ach gas.Most swallowed air appears to be eructated before it gets to the stomach.If supine may pass into the small intestine- Swallowed air is the major source of O2 and N2 in intestinal gas. -From digestion of fat and protein in the upper GI tract-From bacterial fermentation of intraluminal substrates (accounts for most flatus CO2)- can be worse with non-digestible carbohydrates-Liberated from the interaction of acid and bicarbonate.1. Occurs in the colon especially with high carbohydrate content - With not easily digestiable carbs such as stachyose and raffinose found in legumes, or resistant starches (flours made from wheat, oats, potatoes, and corn) 2. Or from small bowel bacterial fermentationMainly from Methanobrevibacter smithii which reduces colonic gas through 4H2 + CO2> CH4 + 2H20, CH4 usually absorbed into portal circulation and expired or passed in flatusRegulated by presence of bile acids in colonIncreased in:Colorectal cancerExtensive ulcerative colitisColonic polypsSulfur-containing compounds such as methanethiol, dimethylsulfide, hydrogen sulfideShort-chain fatty acids, skatoles, indoles, volatile amines, and ammonia. [N2] Eructation =“retrograde passage of esophageal or gastric gas out of the mouth”It is an involuntary belching due to release of swallowed air usually after a meal.It is worse with foods that relax LOS (chocolate, fats, and mints).GORD patients may find relief through belching.Patients can have chronic, repetitive belching due to habitual air swallowing (aerophagia). Volume: 500 to 1500 mL per day (passage of flatus 10-20x/day)Rarely associated with serious illnessOffensive odor due to sulfur-containing compounds, such as methanethiol, dimethylsulfide, and hydrogen sulfide, as well as short-chain fatty acids, skatoles, indoles, volatile amines, and ammonia.-Alteration of intestinal motility or bacteria, perhaps due to an antibiotic or other drug.-Dietary factors, such as an increased intake of lactose, fructose, sorbitol, undigestible starches (such as bran), and carbonated beverages.-Products such as pork, upon digestion, may release trace concentrations of very malodorous gases.DiagnosisEvaluate if any alarm signalsTreatmentAvoid contributing foodsSimethicone not shown to be usefulActivated charcoal may be usefulBeano™, an alpha-galactosidase preparation may be usefulTreat bacterial overgrowth if necessaryBismuth subsalicylate makes it less smellyExternal devices:Carbon fibre pants are highly effective, charcoa; cushions are not Written by Dr Sebastian Zeki Diagnosis- Only investigate if other pathology presentAerophagia criteria (Rome III) includes:-Troublesome repetitive belching at least several times a week-Air swallowing that is objectively observed or measuredRome III criteria also recognized a separate disorder of "unspecified excessive belching":-Troublesome repetitive belching at least several times a week-No evidence that excessive air swallowing underlies the symptoms-These criteria should be fulfilled for the last three months with symptom onset at least 6m before diagnosisTreatmentFor chronic eructation suggest ways to stop aerophagia (stop gum chewing, smoking, drinking carbonated beverages, and gulping food and liquids) Flatulence [CO2] [H2] [CH4] Also: