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
|
|