13.09.12 Short bowel syndrome

Types Jejunoileal resection and a jejunocolic anastomosis (jejunum-colon) Predominantly jejunal resection with more than 10 cm of terminal ileum and the colon remaining (jejunum-ileum) Jejunoileal resection, colectomy, and formation of a stoma (jejunostomy) Clinical pictures Jejunum-ileum Rarely need long term enteral or parenteral nutrition Jejunum-colon Gradual undernutrition dominates the clinical picture Due to adaptation, nutritional requirements may reduce with time May need parenteral nutrition if less than 50 cm small intestine remains  Need a high carbohydrate low oxalate diet The volume of food may increase diarrhoea (grade A) Jejunostomy Fluid and electrolyte losses dominate the clinical picture Adaptation does not occur so nutritional and fluid requirements do not reduce with time If less than 200 cm of jejunum remains, oral hypotonic fluids may need to be restricted  A glucose-saline supplement (sodium concentration of about 100 mmol/l) is sipped to reduce stomal losses of sodium Hypomagnesaemia is common and is treated by correcting sodium depletion, oral or intravenous magnesium supplements And occasionally with oral 1 alpha hydroxycholecalciferol Jejunal output may be further reduced by drugs that reduce motility (loperamide)  Or, if the bowel is very short (less than 100 cm), drugs that reduce gastric acid secretion (H2 antagonists, PPIs, or somatostatin analogues)  Common causes of a short bowel Jejunum-colon Crohn’s disease  Mesenteric ischaemia  Irradiation  Small bowel volvulus  Adhesions  Jejunostomy Crohn’s disease UC Irradiation Mesenteric ischaemia Desmoid Physiological consequences Gastrointestinal motility Gastric emptying and small bowel transit for liquid is normal in jejunum-colon patients but fast in patients with a jejunostomy  Ileal and colonic braking mechanisms have been resected May relate to circulating plasma levels of peptide YY and glucagon-like peptide 2 (GLP-2)  Gastrointestinal secretions  The majority of this fluid is reabsorbed in the upper jejunum Jejunum-colon patients can reabsorb unabsorbed fluid in their colon but this is not the case for jejunostomy patients who lose much salt and water from their stoma Jejunal mucosa is ‘‘leaky’’ and rapid sodium fluxes occur across it If water or any solution with a sodium concentration of less than 90 mmol/l is drunk there is a net efflux of sodium from the plasma into the bowel lumen Gastric acid hypersecretion may occur in the first two weeks after a small bowel resection Absorptive functions Vitamin B12 and fat malabsorption occurs when more than 60–100 cm of terminal ileum have been resected Increased hepatic synthesis of bile salts cannot compensate for the loss of ileal surface area Unabsorbed bile salts may contribute to colonic secretion in patients with a remaining colon Magnesium deficiency occurs due to because of chelation with unabsorbed fatty acids and increased renal excretion (secondary hyperaldosteronism) Hypomagnesaemia reduces the secretion and function of parathormone Management of undernutrition 50% or more of the energy from the diet may be malabsorbed Parenteral nutrition should be avoided unless absolutely necessary May only be needed for a few weeks or months before oral supplements are adequate In the long term, parenteral nutrition is needed if a patient absorbs less than one third of the oral energy intake Unabsorbed long chain fatty acids in the colon (In jejunum-colon patients) Reduce transit time and reduce water and sodium absorption so making diarrhoea worse Toxic to bacteria and so reduce carbohydrate fermentation Bind to calcium and magnesium, increasing stool losses Increase oxalate absorption so predisposing to the formation of renal stones A low fat diet may increase calcium, magnesium, and zinc absorption but makes essential fatty acid deficiency more likely Medium chain triglycerides are an alternative source of energy and are absorbed from the small and large bowel If a diet is high in monosaccharides D-lactic acidosis may occur  Vitamin and mineral deficiencies Most patients require long term B12 treatment Selenium deficiency is common and patients may need larger amounts than normal subjects Zinc deficiency is uncommon unless stool volumes are large Vitamins A, D, E, and K, and essential fatty acids may need to be replaced Management of a patient with a jejunostomy Exclude/treat causes other than a short bowel Infection (intra or extraluminal) Partial obstruction Abrupt stopping of drugs Correct dehydration with intravenous saline while the patient takes nothing by mouth for 24–48 hours This stops thirst and thus the desire to drink  Reduce oral hypotonic fluids to 500 ml/day This is the most important measure Give glucose/saline solution to sip (sodium concentration at least 90 mmol/l) Most stomal/fistula losses (except from the colon) have a sodium concentration of about 100 mmol/l  Add sodium chloride to any liquid feeds to make the sodium concentration near to 100 mmol/l while keeping osmolality near 300 mosmol/kg  Give drugs to reduce motility Loperamide 2–8 mg (non-sedative and non-addictive) before food Occasionally, addition of codeine phosphate further reduces stomal output If there is net ‘‘secretory’’ output (generally more than 3 l/24 hours), drugs that reduce gastric acid secretion can reduce stomal output by 1–2 l/24 hours H2 antagonists or proton pump inhibitors Octreotide if unable to absorb oral drugs, octreotide Other measures include: Separating solids and liquids (that is, having no drink for half an hour before or after food) Using salt capsules instead of glucose/saline solution  A trial of fludrocortisone if the ileum remains  Correct hypomagnesaemia  Intravenous magnesium sulphate initially then oral magnesium oxide and/or 1-alpha cholecalciferol Summary Notes Bowel length measurements are from the duodenojejunal flexure  Can be made at surgery or with the use of an opisiometer tracing out the long axis of the bowel on a contrast study Normal human small intestinal length varies from about 275 cm to 850 cm, and tends to be shorter in women In general, nutritional/fluid supplements are likely to be needed if less than 200 cm of small bowel remains Daily gastrointestinal secretions: 0.5 litre of saliva 2.0 litres of gastric juice 1.5 litres of pancreaticobiliary secretions plus passive jejunal secretions Drug absorption may be impaired