Fiser Chapter 10 NUTRITION Flashcards
Caloric need
20-25 calories/kg/day
Calories in different forms
Fat 9 calories/g
Protein 4 calories/g
Oral carbohydrates 4 calories/g
Dextrose 3.4 calories/g
Nutritional requirements
20% protein
30% fat
50% carbohydrates
Trauma, surgery, sepsis increase kcal requirement
20-40% increase
Caloric need equation if overweight
weight = [(actual weight - ideal body weight) x 0.25] + IBW
Colonocyte fuel
Short-chain fatty acids (butyric acid)
Small bowel enterocyte fuel
Glutamine
Releases NH4 in kidney, helping with nitrogen excretion
Can be used for gluconeogenesis
Neoplastic cells fuel
glutamine
Albumin half life
18 days
Transferrin half life
10 days
Prealbumin half life
2 days
Acute indicators of nutrition
Retinal binding protein
Prealbumin
Transferrin
IBW
Men: 106 lb + 6 lb for each inch over 5ft
Women = 100 lb + 5 lb for each inch over 5 ft
Preop signs of poor nutrition
Acute weight loss > 10% in 6 months
Weight
Albumin < 3.0 (strong risk factor for M&M after surgery)
RQ ratio
CO2 produced : O2 consumed
RQ > 1
Lipogenesis (overfeeding)
RQ < 0.7
ketosis and fat oxidation (starvation)
RQ 0.7 exactly
Pure fat utilization
RQ 0.8 exactly
Pure protein utilization
RQ 1 exactly
Pure carbohydrate utilization
Postoperative phases
0-3 catabolic (negative nitrogen balance)
2-5 diuresis
3-6 anabolic (positive nitrogen balance)
Glycogen stores
Muscle and liver
Depleted after 24-36 hours, then fat
Muscle lacks G6Pase
Gluconeogensis precursors
AAs (alanine)
Lactate
Pyruvate
Glycerol
Do protein conserving mechanisms occur after trauma or surgery?
No due to catecholamines and cortisol
Do protein conserving mechanisms occur with starvation?
yes
Main source of energy in starvation and trauma
Fat (ketones)
Trauma: more mixed (fat and protein) than starvation
T/F most patients can tolerate a 15% weight loss without major cx?
True
How long can patients tolerate without eating, after which should start tube feeds or TPN?
7 days
Why is enteral feeding important?
To avoid bacterial translocation (bacterial overgrowth, increased permeability due to starved enterocytes, bacteremia) and TPN complications
What does brain use for energy?
Normally glucose –> ketones during starvation
What are the obligate glucose users?
Peripheral nerves
Adrenal medulla
RBCs
WBCs
Refeeding syndrome symptoms
Low K, Mg, PO4
Cardiac dysfunction
Weakness
Encephalopathy
Prevent by starting at low rate (10-15 kcal/kg/day)
Cachexia is mediated by what?
TNF-alpha
Glycogen breakdown, lipolysis, protein catabolism
Kwashiorkor versus Marasmus
Kwashiorkor: protein deficiency
Marasmus: starvation
How much nitrogen does 6.25 g of protein contain?
1 g nitrogen
Nitrogen balance equation
N in - N out = (protein/6.25) - (24hr urine N + 4 g)
Positive N balance versus Negative N balance
Positive = anabolism
Negative = catabolism
Total protein synthesis for a healthy 70kg male is what?
250 g / day
What organ is responsible for amino acid production and breakdown?
Liver
Urea production is used for what?
To get rid of ammonia from amino acid breakdown
Majority of protein breakdown from skeletal muscle is what amino acids?
Glutamine
Alanine
How do short, medium, and long chain fatty acids enter enterocytes?
Short and medium: simple diffusion, into portal system, like amino acids and carbs
Long: enter lymphatics along with chylomicrons
Vitamin deficiency causing hyperglycemia, encephalopathy, neuropathy?
Chromium deficiency
Vitamin deficiency causing cardiomyopathy and weakness?
Selenium
Vitamin deficiency causing pancytopenia?
Copper
Vitamin deficiency causing poor wound healing?
Zinc
Vitamin deficiency causing weakness (failure to wean off vent), encephalopathy, decreased phagocytosis?
Phosphate
Vitamin deficiency causing Wernicke’s encephalopathy, cardiomyopathy?
Thiamine (B1)
Vitamin deficiency causing sideroblastic anemia, glossitis, peripheral neuropathy?
Pyridoxine (B6)
Vitamin deficiency causing megaloblastic anemia, peripheral neuropathy, beefy tongue?
Cobalamin (B12)
Vitamin deficiency causing megaloblastic anemia, glossitis?
Folate
Vitamin deficiency causing diarrhea, dermatitis, dementia?
Niacin (pellagra)
Vitamin deficiency causing dermatitis, hair loss, thrombocytopenia?
Essential fatty acids (leucine, isoleucine, valine, arginine, histidine, lysine, methionine, phenylalanine, threonine, tryptophan)
Vitamin deficiency causing night blindness?
Vitamin A
Vitamin deficiency causing coagulopathy?
Vitamin K
Vitamin deficiency causing rickets, osteomalacia, osteoporosis?
Vitamin D
Vitamin deficiency causing neuropathy?
Vitamin E