2- intestinal failure Flashcards
what absorption type processes occur in the stomach?
- intrinsic factor binds to b12
- pepsin begins digestion of protein
- Fe3+ to Fe2+
what absorption occurs in duodenum?
- iron absorbed (Fe2+)
pancreatic digestive enzymes like lipases, proteases, amylase help: - break proteins down to amino acids that are then absorbed
- break polysaccharides to disaccharides
- along with bile salts emulsify triglycerides to break down to fatty acids + monoglycerides
what absorption occurs in jejunum?
- brush border disaccharides broken down to monosaccharides which are absorbed
absorbed:
- calcium
- folate
- fat soluble vitamins
- free fatty acids
- monoglycerides
- small amount of b12 a
- moderate amount of water
- small amount of sodium
what absorption and processes occur in ileum?
- b12 absorbed
- moderate amount of water + sodium absorbed
- intrinsic factor absorbed for reuse
- bile acids reabsorbed for recycling to liver
what absorption and processes occur in colon?
small amount is absorbed of:
- water
- electrolytes
- bile acids
describe the whole fluid secretion & absorption of GI tract
*hint = start with dietary input and end with what’s lost in faeces
- 2L (dietary input) + 1.5L (digestive secretions)
- +1.5L (gastric secretions) = 5L
- +1L (liver) and 1L (pancreas) + 2L (intestine) = 9L
- small intestine reabsorbs 7.8L so 1.2L left
- colonic mucous secretions = 0.2L = 1.4L
- 0.15L lost in faeces and colonic reabsorbs 1.25L
what are things absorbed in colon?
- bile acids
- electrolytes (sodium, potassium, calcium)
- water
what are the GI tract transit times
10 seconds from mouth →oesophagus
3hrs →get to stomach
7-9 hours →through small bowel
25-30 hours →large intestine/colon
30-120 hours →excretion in rectum
what is intestinal failure?
= inability to maintain adequate nutrition or fluid status via the intestines
= reduction in function below the min necessary for absorption of macronutrients and / or water and electrolytes such that intravenous supplementation is required to maintain health and / or growth
what are causes of TYPE 1 intestinal failure?
type 1= short term
- surgical ileus (bowel can stop functioning straight after surgery making build up in stomach and lack of absorption)
- critical illness
GI problems that can cause:
- vomiting
- dysphagia
- pancreatitis (inflamed so no exocrine function for digestive enzymes to break down food)
- GI obstruction
- diarrhoea
- oncology (chemo or radiotherapy cause inflammation making pain, loss appetite)
what are causes of TYPE 2 intestinal failure?
type 2 = unable to absorb enough nutrients and fluids to maintain adequate nutrition and hydration over the long term
= occurs as a result of structural or functional abnormalities within GI tract
- vascular embolism
- crohns disease
- narrowing of superior mesenteric artery compromising blood suppply - causing pain
- radiation (no absorb, can be unpleasant, painful)
- adhesions (bowels loops + don’t function)
- fistulae (abnormal connections forming between e.g small bowel and colon which skips areas of absorption)
what are causes of TYPE 3 intestinal failure?
chronic = because of disease process have developed short bowel syndrome
- crohns
- radiation
- dysmotility
- malabsorption
- inoperable obstruction e.g. cancer
- volvulus = bowel twists cutting off supply
- vascular disaster
briefly describe differences between 3 types of intestinal failure?
type 1 = self limiting
type 2 = significant & prolonged parenteral nutrition support (>28 days)
type 3= chronic IF (long term parenteral nutrition) = can be at home
what is support/treatment for type 1 IF?
- replace fluid, correct electrolytes (e.g. if losing magnesium or sodium, boost where needed)
- can sometimes supply short term IV nutrition if unable to tolerate food
- acid suppression with proton pump inhibitors to prevent developing stress ulcers
- allow some oral diet feeding e.g. build up from soups + custards
what is support/treatment for type 2 IF?
- > 4 weeks (ICU/HDU)
- Parenteral nutrition +/- some enteral feeding (oral or naso-gastric tube)
what is support for type 3 IF?
total parenteral nutrition = can be from months to years - can also do at home
- intestinal transplantations but only specific cases (long term survival lower than HPN)
- glucagon like peptide-2 can lengthen gut but increases risk for developing malignancy and expensive
- bowel lengthening procedures (yet to be validated in adults)
what is short bowel syndrome?
it’s when small intestine from jejunum to ileum too small - normally it’s 6-7m long
<200cm = short bowel
<50cm = ultra short bowel
→means insufficient length of small bowel to meet nutritional needs without artificial nutritional support
short bowel can lead from conditions that then means type 3 IF
what are 4 types of short bowel?
- jejunostomy
- ileostomy
- jejuno-colic anastomosis
- ileo-colic anastomosis
what is the significance about where bowel left in short bowel?
depending on where stoma is makes different implications for treatment
what is jejunostomy?
→due to gastroparesis, obstruction in duodenum/stomach, malabsorption disorders, gastric surgery
= surgical operation to allow stoma (artificial opening) which means direct access for nutritional and fluid
what is ileostomy?
= usually done when the colon is removed or bypassed due to disease or injury, such as in cases of ulcerative colitis or Crohn’s disease
= surgical operation to allow stoma, but this time for a bag to be filled with waste directly from small intestine bypassing colon - absorption can still occur in rest of small intestine
what is jejunocolic anastomosis?
→done if short bowel syndrome, colon resection = as bowel rehabilitation →done to make flow through GI tract (usually done if block/insufficient absorption)
= surgically connecting jejunum + transverse colon, by creating anastomosis, the nutrient absorption enhanced as colon can aborb water + electrolytes
what is ileocolic anastomosis?
= done when problem with small intestine (especially ileum)
= involves surgically connecting ileum to ascending colon, anastomosis optimises nutrient absorption
what is parenteral nutrition?
delivering nutrients directly into the bloodstream through intravenous (IV) access, bypassing the digestive system.
