Nutrition support Flashcards
What is the % breakdown of different food groups
20% - proteins: 1g/kg/day
30% fats
50% carbohydrates
Explain carbohydrate digestion
It begins with salivary amylase, then pancreatic amylase and disaccharides
Glucose and galactose are absorbed by secondary active transport
Fructose by facillitated diffusion
- Both then enter portal vein
Provides 4.1kcal/g
Explain protein digestion
Begins with stomach pepsin
Trypsinogen is converted to trypsin by enterokinase and breaks down protein.
Protein is broken down into amino acids, dipeptides, tripeptides and is then absorbed by secondary active transport
Provides 5.3kcal/g
What are the essential amino acids
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Explain fat digestion
TAG, cholesterol and lipids are broken down by pancreatic lipase, cholesterol esterase and phospholipase to micells and FFA.
Fat soluble vitamins are absorbed through these micelles
Within the enterocytes the micelles along with FFA form chylomicrons, long-fatty chains, medium and short chains
What are the essential fats
Linolenic
Linoleic
Arachidonic acid
What are the acute indicators for nutritional status
- pre-albumin (#1)
- retinal binding protein
- transferrin
What are the pre-operative signs of severe malnutrition
- Acute weight loss > 20% in 3 months
- Albumin < 34 g/L
- Anergy to skin antigens
What is the simple basal energy expenditure formula used at bedside
25 x bodyweight(in kg)
Explain nitrogen balance
6.25g of protein contains 1g of nitrogen
Positive Nitrogen balance results in anabolism while negative Nitrogen balance results in catabolism
90% of N is removed in the urea cycle through the kidney
What are the effects of surgery on the body
It results in an increase in kcal requirement by about 20-40%
List the post-operative phases
Diuresis: days 2-5
Catabolic: days 0-3
Anabolic: days 3-6
What happens to glycogen stores in times of stress
Glycogen stores are depleted in about 24-36 hours and the body then switches over to fat
Liver is the main source of glucose during stress response
Explain the compensatory mechanisms in starvation
Body switches over to fat(ketones) for energy as a way to save protein content as fat is the bodies largest potential energy source
Most patients can tolerate about 7days without eating
Explain refeeding syndrome
It is feeding after a long period of starvation/malnutrition and r3sults in body shifting back from fat to carbohydrate metabolism
Symptoms usually occur on day 4 and results in: decreased K, Mg, PO4
- cardiac dysfunction
- Profound weakness
- Encephalopathy
- CHF
- Failure to wean from ventilator
Start refeeding at slow rate: 10-15kcal/kg/day
