CHAPTER 10- NUTRITION.txt

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CHAPTER 10- NUTRITION.txt
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  1. Caloric need:
    approximately 25 kcal/kg/day
  2. Composition of a Standard Central Venous Solution:
    • Volume:
    • 10% Amino Acid solution- 500ml
    • 50% dextrose solution -500ml
    • Fat emulsion -
    • Electrolytes+vitamins+minerals - ~50ml
    • Total volume: ~ 1,050

    • Composition:
    • Amino acids- 50g
    • Dextrose- 250g
    • Total N- 8g = (50/6.25)
    • Dextrose kcal: 840kcal = (250g x 3.4kcal/g)
    • MOsms/L: ~2,000
  3. Electrolytes added to TPN (total parenteral nutrition) solutions:
    Electrolyte/Usual Concentration/ Range of Concentrations

    • Sodium: 60 (0-150)
    • Potassium: 40 (0-80)
    • Acetate: 50 (50-150)
    • Chloride: 50 (0-150)
    • Phosphate: 15 (0-30)
    • Calcium 4.5 (0-20)
    • Magnesium: 5 (5-15)
  4. How many kcal/g in:
    Fat:
    Protein:
    Oral carbohydrates:
    Dextrose:
    10% lipid:
    20% lipid solution:
    • Fat: 9 kcal/g
    • Protein: 4 kcal/g
    • Oral carbohydrates: 4 kcal/g
    • Dextrose: 3.4 kcal/g
    • 10% lipid solution: 1.1 kcal/cc
    • 20% lipid solution: 2 kcal/cc
  5. Nutritional requirements for average healthy adult male:
    • 1) 1g protein/kg/day is needed, of which 20% should be essential amino acids
    • 2) 30% fat calories- important for essential fatty acids
    • 3) rest of calories should be as carbohydrates
  6. What factors can increase the kcal requirement, and by how much?
    • 1) Trauma, surgery, or sepsis stress can increase kcal requirement 20-40%
    • 2) Pregnancy increases kcal requirement 300kcal/day
    • 3) Lactation increases kcal requirement 500kcal/day
    • 4) Protein requirement also increases with these
  7. Burns:
    • Calories: 25 kcal/kg/day + (30 kcal/day x % burn)
    • Protein: 1-1.5 g/kg/day + (3g x % burn)
  8. What is much of the energy expenditure used for?
    heat production
  9. What happens to the basal metabolic rate in relation to temperature?
    Basal metabolic rate increases 10% for each degree above 38C
  10. If overweight, use the following equation to determine patient's weight:
    • Weight =
    • [(actual weight- ideal body weight) x 0.25]+ IBW
  11. What is the Harris-Benedict Equation:
    • Harris-Benedict equation calculates basal energy expenditure based on:
    • 1) weight
    • 2) height
    • 3) age
    • 4) gender
  12. Central line TPN:
    • 1) glucose based
    • 2) maximum glucose administration: 3g/kg/h
  13. Peripheral line parenteral nutrition (PPN):
    fat based
  14. See table on pg 44: Metabolic Differences between the response to simple starvation and injury
  15. What is the fuel for colonocytes?
    short-chain fatty acids
  16. Glutamine
    • 1) fuel for small bowel enterocytes
    • 2) most common amino acid in bloodstream and tissue
    • 3) releases NH4 in the kidney, thus helping with nitrogen excretion
    • 4) can be used for gluconeogenesis
  17. What is the primary fuel for neoplastic cells:
    glutamine
  18. Preoperative nutritional assessment (following slides):
  19. Approximate half-lives of:
    Albumin:
    Transferrin:
    Prealbumin:
    • Albumin: 20 days
    • Transferrin: 10 days
    • Prealbumin: 2 days
  20. Normal protein level:
    6.0-8.5
  21. Normal albumin level:
    3.3-5.5
  22. Acute indicators of nutritional status:
    • 1) retinal binding protein
    • 2) prealbumin
    • 3) transferrin
    • 4) total lymphocytes count
  23. Ideal body weight (IBW)
    • Men= 106 lb + 6 lbs for each inch over 5 ft
    • Women= 100 lb + 5 lbs for each inch over 5 ft
  24. Preoperative signs of poor nutritional status:
    • 1) acute weight loss >10% in 6 months
    • 2) weight <85% of IBW
    • 3) Albumin <3.0
    • 4) low albumin (<3.0)- strong risk factor for morbidity and mortality after surgery
  25. Respiratory Quotient (RQ)
    1) Ratio of CO2 produced to O2 consumed- measurement of energy expenditure

    • 2) RQ>1= lipogenesis (overfeeding)
    • 1- Tx: decrease carbohydrates and caloric intake
    • 2- high carbohydrate intake can lead to CO2
    • 3- buildup and ventilator problems

    • 3) RQ<0.7= ketosis and fat oxidation (starving)
    • 1- Tx increase carbohydrates and caloric intake

    • 4)
    • Pure fat metabolism: RQ= 0.7
    • Pure protein metabolism- RQ=0.8
    • Pure carbohydrate metabolism- RQ=1
  26. Postoperative phases
    • 1) Diuresis phase- postoperative days 2-5
    • 2) Catabolic phase- postoperative days 0-3 (negative nitrogen balance)
    • 3) Anabolic phase- postoperative days 3-6 (positive nitrogen balance)
  27. Starvation or major stress (surgery trauma, systemic illness)- slides to follow
  28. Glycogen stores:
    • 1) depleted after 24-36 hours of starvation (2/3 in skeletal muscle, 1/3 in liver)--> body then switches to fat
    • 2) skeletal muscle lacks glucose-6-phosphatase (found only in liver)
    • 3) glucose-6-phosphate stays in muscle after breakdown from glycogen and is utilized
  29. Gluconeogenesis precursors:
    • 1) amino acids (especially alanine), lactate, pyruvate, glycerol
    • 2) Alanine is the simplest amino acid precursor for gluconeogenesis
    • 1- primary substrate for gluconeogenesis
    • 3) Alanine and phenylalanine- only amino acids to increase during time of stress
    • 4) Late starvation- gluconeogenesis occurs in kidney
  30. Starvation
    • 1) protein-conserving mechanisms do not occur after trauma or surgery) secondary to catecholamines and cortisol
    • 2) protein-conserving mechanisms do occur in starvation
    • 3) Fat (ketones) is the main source of energy in trauma and starvation
    • 4) most patients can tolerate a 15% weight loss without major complications
    • 5) patients can tolerate about 7 days without eating; if longer than that, place a Dobhoff tube or start TPN
    • 6) try to feed gut to avoid bacterial translocation (bacterial overgrowth, increased permeability due to starved enterocytes)
    • 7) Elemental formula- all protein given in the form of amino acids (given IV, expensive)
    • 8) PEG- consider when regular feeding not possible (i.e. CVA) or predicted to not occur for >4 weeks
  31. What energy does brain use?
    Brain- utilizes ketones with progressive starvation (normally uses glucose)
  32. Name structures that are obligate glucose users:
    • 1) peripheral nerves
    • 2) adrenal medulla
    • 3) red blood cells
    • 4) white blood cells
  33. Refeeding syndrome
    • 1) occurs when feeding after prolonged starvation/malnutrition
    • 2) results in decreased K, Mg, and PO4; causes cardiac dysfunction and fluid shifts
    • 3) prevent this by starting at a low rate (10-15 kcal/kg/day)
  34. Cachexia
    • 1) anorexia, weight loss, starvation/malnutrition
    • 2) thought to be mediated by TNF-alpha
    • 3) glycogen breakdown, lipolyisis, protein catabolism
  35. Kwashiorkor
    protein deficiency
  36. Marasmus
    starvation
  37. See image on pg 46: Homeostatis adjustments initiated after injury
  38. Nitrogen balance:
    • 1) 6.25g of protein contains 1g of nitrogen
    • 2) N balance= (N in - N out)= ([protein/6.25] - [24hour urine N + 4 g])
    • 1- Positive N balance- more protein ingested than excreted (anabolism)
    • 2- Negative N balance- more protein excreted than taken in (catabolism)
    • 3) total protein synthesis for a healthy, normal 70kg male is 250g/day
  39. Liver
    • 1) responsible for amino acid production and breakdown
    • 2) Urea production to get rid of ammonia from amino acid breakdown
    • 3) majority of protein breakdown from skeletal muscle is glutamine and alanine
  40. Fat Digestion
    • 1) Triacylglycerides (TAG), cholesterol, and lipids
    • 1- broken down by pancreatic lipase, cholesterol esterase, and phospholipase to micelles and free fatty acids
    • 2- Micelles- aggregates of bile salts, long-chain free fatty acids, and monoacylglycerides
    • a- enter enterocytes by fusing with membrane
    • b- Bile salts- increase absorption area for fats, helping form micelles
    • c- Cholesterol- used to synthesize bile salts
    • d- fat soluble vitamins (A,D,E,K)- absorbed in micelles
    • 2) Medium and short chain fatty acids- enter enterocyte by simple diffusion
    • 3) Micelles and other fatty acids enter enterocytes--> chylomicrons are formed, which enter lymphatics (thoracic duct)
    • 4) Chylomicrons- 90% TAGs, 10% phospholipids/proteins/cholesterol
    • 1- medium-and short-chain fatty acids- enter portal system (same as amino acids and carbohydrates
    • 2- long chain fatty acids- enter lymphatics along with chylomicrons
  41. Lipoprotein lipase-
    on liver endothelium, clears chylomicrons and TAGs from the blood, breaking them down to fatty acids and glycerol, which are then taken up by hepatocyte
  42. Free fatty acid-binding protein
    • 1) on liver endothelium
    • 2) binds short and medium chain fatty acids
  43. VLDL
    most important route of entry for dietary cholesterol; synthesized in liver
  44. Saturated fatty acids
    • 1) used for fuel by cardiac and skeletal muscles
    • 1- Fatty acids (ketones- acetoacetate, beta-hydroxybutyrate)- preferred source of energy for the liver, heart, and skeletal muscle
  45. Unsaturated fatty acids
    used as structural components for cells
  46. Hormone-sensitive lipase:
    • 1) in fat cells
    • 2) breaks down TAGs (storage form of fats) to fatty acids and glycerol; released into blood (sensitive to growth hormone, catecholamines, glucocorticoids)
  47. Essential fatty acids-
    • 1) linolenic, linoleic
    • 2) needed for prostaglandin synthesis (long-chain fatty acids)
    • 3) important for immune cells
  48. Omega-3-fatty acids:
    • All odd- thought to have antioxidant properties
    • 1) PGI3
    • 2) TXA3
    • 3) LTB5
  49. Omega-6-fatty acids
    • All even
    • 1) PGE2
    • 2) TXA2
    • 3) LTB4
  50. Carbohydrate digestion:
    • 1) begins with salivary amylase, then pancreatic amylase and disaccharidases
    • 2) Glucose and galactose- abosrbed by secondary active transport; released into portal vein
    • 3) Fructose- facilitated diffusion; released into portal vein
    • 4)
    • Sucrose- fructose + glucose
    • Lactose- galactose + glucose
    • Maltose- glucose + glucose
  51. Protein Digestion:
    • 1) begins with:
    • 1- stomach pepsin
    • 2- then trypsin, chymotripsin, and carboxypeptidase
    • 2) Trypsinogen released from pancreas and activated by enterokinase released from duodenum
    • 1- other pancreatic protein enzymes are then activated by trypsin
    • 2- trypsin can then also autoactivate other trypsinogen molecules
    • 3) Protein broken down to amino acids, dipeptides, and tripeptides by proteases
    • 4) absorbed by secondary active transport; released as free amino acids into portal vein
    • 5) may want to limit protein intake in patients with liver failure and renal failure to avoid ammonia buildup and possible worsening encephalopathy
  52. Branched-chain amino acids-
    • 1) leucine
    • 2) isoleucine
    • 3) valine
    • (acronym: "LIV")

    • 1) metabolized in muscle
    • 2) possibly important in patients with liver failure
    • 3) are essential amino acids
  53. Cori cycle:
    • 1) glucose is utilized and converted to lactate in muscle
    • 2) lactate then goes to the liver and is converted back to pyruvate and eventually glucose via gluconeogenesis
    • 3) glucose is then transported back to muscle
  54. Deficiencies:
    Chromium-
    Selenium-
    Copper-
    Zinc-
    Trace elements-
    Phosphate-
    Thiamine (B1)-
    Pyridoxine (B6)-
    Cobalamine (B12)-
    Folate-
    Niacin-
    Essential fatty acids-
    Vitamin A-
    Vitamin K-
    Vitamin D-
    Vitamin E-
    • Chromium- hyperglycemia, encephalopathy, neuropathy
    • Selenium- cardiomyopathy, weakness, hair loss
    • Copper- pancytopenia
    • Zinc- hair loss, poor healing, rash
    • Trace elements- poor wound healing
    • Phosphate- weakness (failure to wean off ventilator), encephalopathy, decrease phagocytosis
    • Thiamine (B1)- wernicke's encephalopathy, cardiomyopathy, peripheral neuropathy
    • Pyridoxine (B6)- sideroblastic anemia, glossitis, peripheral neuropathy
    • Cobalamine (B12)- megaloblastic anemia, peripheral neuropathy, beefy tongue
    • Folate- megaloblastic anemia, glossitis
    • Niacin- pellagra (diarrhea, dermatitis, dementia)
    • Essential fatty acids- dermatitis, hair loss, thrombocytopenia
    • Vitamin A- night blindness
    • Vitamin K- coagulopathy
    • Vitamin D- rickets, osteomalacia
    • Vitamin E- neuropathy

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