229 - Nutrition Flashcards
Define short bowel syndrome?
state of malabsorption and malnutrition following massive anatomical or function loss (decr motility and absorption) of the small intestine - normally when less than 2m
what conditions would cause surgical resection to be needed?
- crohn’s disease (IBD)
- Ischaemic bowel
- cancer
- trauma
- Intussuception - part of intestine folds into another
- In newborns - infection (necrotising enterocolitis in premature infants) and congenital defects (volvulus, merconium ileus due to cystic fibrosis and hirchsprungs)
what chronic complications does short bowel syndrome cause?
- secretory diarrhoea as ileum cant reabsorb fluids secreted higher up in the GIT
- Decr fat uptake and malnutrion: steatorrhoea, decr fat soluble vit uptake (clotting abnormalities vit K and osteoporosis vit D, renal stones as more oxalate absorbed (ca binfs to FFAs instead)
- Decr Bile reabsorption: gallstones, decr fat uptake, colonic irritation
- hypergastrinaemia - -ve feed back for gastrin removed : excess acid secretion, PUD and oesophagitis
What can be done to treat short bowel syndrome?
- enteral feeding stimulates gut adaptation in small continuous quantities. Fats and proteins in large amounts to decr osmotic load
- PPIs to reduce acid secretion
What does the jejunum do?
- 1.4m long with large number of villi, deep crypts and large surface area with high conc of digestive enzymes
- dependent on thyroid hormone for epithelium maintenance
- absorbs carbs (glucose), fat, protein (amino acids), thiamine (vit B1) and vit c
- net secretor of water and electrolytes
what does resectioning of the jejenum do?
*temp reduction in most nutrient absorption but the ileum compensates over time by growing in length and diameter and producing more villi and crypts. This is stimulated by excess lipid presence in the ileum. Trophic hormones produced in the ileum like GLP2
what does the ileum do?
- 5m long with fewer villi than jejenum and shallower crypts. absorbs:
* water and electrolytes secreted earlier in GIT
* Fat soluble vits A (retinal production), D (incr ca absorption) E (antioxidant) and K (activation of coagulation factors
* zinc and phosphorus
* terminal ileum - bile acids and vit B12 with intrinsic factor (req for DNA synthesis)
what does resectioning of the ileum do?
- fluid and electrolyte loss (diarrhoea)
- impaired fat absorption causing impaired fat soluble vit absorption (due to inability to reabsorb bile acids
- impaired vit B12 absorption leading to pernicious anaemia
- Colonic irritation
what does the ileocaecal valve do?
- acts as an ileal brake (controlled by peptide YY and neurotensin
- prevents reflux of material from colon back into SI and hence bacterial overgrowth
what does resection of the ileocaecal valve do?
- Decr absorption of most nutrients due to rapid passage through SI
- Bacterial overgrowth in the SI causing dilatation and decr motility and inflammation/infections
what does the colon do?
- absorb water, electrolyte and some fatty acids
* slow intestinal transit
How does the colon react to SI resection?
- Some adaptation but not effective. Some carbs after conversion to short chain FAs by gut flora
- Irritation due to changed luminal contents causing secretory diarrhoea and increased malignancy risk due to changes
what are the pre-requisites for enteral feeding?
- functioning gut
- cannot meet nutritional needs with normal food
- > 10% weight loss in 3/12
- hypermetabolic
what are the pros and cons of enteral feeding?
pros:
*stimulates gut adaptation and preserves intestinal mucosal structure
*prevents biliary sludge and independent of swallowing
cons:
*diarrhoea (give small quantities and continuously) and fluid overload (give fats and proteins to decr osmotic load
*GO reflux and poor gastric emptying
*refeeding syndrome
what are the prerequisites of parenteral feeding?
- non functioning gut
* 7/7 of inadequate nutrition
