Nutrition Basic Science Lecture Series Umut Sarpel 8/11/0

1
Nutrition

• Basic Science Lecture Series
• Umut Sarpel
• 8/11/05

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Overview

• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohns disease
• Issues in bariatric surgery

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Overview

• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohns disease
• Issues in bariatric surgery

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Calorie requirements

• Resting 70 kg male 1450 kcal/day
• Post-operative 1700 kcal/day
• Sepsis, head trauma, pancreatitis
• 2400 kcal/day
• Burns (depends on size) 3000 kcal/day

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Protein requirements

• In healthy adults
• 0.8 gm / kg (56 gm / day for 70 kg patient)
• In stressed patients
• 1.2-1.5 gm / kg

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Overview

• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohns disease
• Issues in bariatric surgery

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Respiratory Quotient

• RQ O2 consumption / CO2 production
• Carbohydrates 1.0
• Protein 0.81
• Lipids 0.7
• Alcohol 0.66
• Normal American diet RQ 0.87
• Excess glucose leads to a RQ gt 1.0

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A patient s/p Whipple complicated by a leak with
prolonged sepsis is now stable. She has failed 2
extubation attempts. Her RQ is likely

• 0.66
• 0.7
• 0.8
• 0.9
• 1.1

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A patient s/p Whipple complicated by a leak with
prolonged sepsis is now stable. She has failed 2
extubation attempts. Her RQ is likely

• 0.66
• 0.7
• 0.8
• 0.9
• 1.1

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Respiratory Quotient

• An RQ gt 1 indicates net lipogenesis
• Overfeeding syndrome is a common reason for
  failed extubation
• The excess glucose, converted to CO2, increases
  minute ventilation in order to prevent
  respiratory acidosis
• Re-evaluate caloric needs

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Overview

• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohns disease
• Issues in bariatric surgery

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Starvation

• Glycogen from liver depleted in 48 hrs
• The body first catabolizes skeletal muscle amino
  acids into glucose
• Certain tissues are highly dependent on glucose
  for energy, thus some glucose production is
  always required
• In prolonged starvation, the body will adjust to
  using fat stores, and proteolysis decreases

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Starvation

• The metabolic tragedy of sepsis
• The normal suppression of proteolysis seen w/
  prolonged fasting does not occur in sepsis
• Breakdown of protein continues
• Also, high cortisol levels lead to persistent
  hyperglycemia which inhibits lipolysis
• Thus septic pts can have enormous untapped fat
  stores and still catabolize muscle

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The primary source for glucose in early
starvation (1week) comes from

• Proteins in skeletal muscle
• Ketone bodies
• Free fatty acids
• Glycogenolysis
• Lipolysis / Acetyl CoA

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The primary source for glucose in early
starvation (1week) comes from

• Proteins in skeletal muscle
• Ketone bodies
• Free fatty acids
• Glycogenolysis
• Lipolysis / Acetyl CoA

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Glucose is the primary fuel source for all the
following tissues except

• Renal medulla
• Brain tissue
• WBCs
• RBCs
• Peripheral nerves
• Heart

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Glucose is the primary fuel source for all the
following tissues except

• Renal medulla
• Brain tissue
• WBCs
• RBCs
• Peripheral nerves
• Heart

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Overview

• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohns disease
• Issues in bariatric surgery

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TPN

• Pre-operative albumin is a predictor of morbidity
  and mortality
• In mildly malnourished patients, pre-op TPN
  increased infectious complications
• In severely malnourished patients, TPN decreased
  non-infectious complications

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TPN

• Refeeding syndrome (aka Phosphate steal) new
  glucose administration leads to rapid
  intracellular shifts of K, Phos, Mg, because they
  are used in glucose metabolism. Sudden drop in
  plasma levels seen.
• Especially, phosphate depletion leads to muscle
  weakness, respiratory distress

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What is the maximum rate of glucose
administration in TPN?

• 1 gm/kg/hr
• 5 gm/kg/hr
• 10 gm/kg/hr
• 15 gm/kg/hr

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What is the maximum rate of glucose
administration in TPN?

• 1 gm/kg/hr
• 5 gm/kg/hr
• 10 gm/kg/hr
• 15 gm/kg/hr
• Besides hyperglycemia, higher rates of glucose
  infusion can also cause vessel thrombosis

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Overview

• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohns disease
• Issues in bariatric surgery

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Enteral feeding

• Nutrients are absorbed into portal system and
  pass through the liver (vs TPN)
• This allows for hepatic and intestinal
  production of products that have a role in
  anabolic signaling, leading to more efficient use
  of nutrients
• Full strength tube feeds may cause an osmotic
  diarrhea
• Always check residuals (lt150cc)

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Enteral feeding

• Immunonutrition enteral diets enhanced with
  omega-3-fatty acids, RNA, vitamins, arginine,
  have been shown to reduce infectious
  complications in patients undergoing surgery for
  malignancy

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Enteral feeding

• Prevents atrophy of intestinal villi
• Prevents translocation of intestinal bacteria
• Prevents immunoglobulin A deficiency
• Usually causes diarrhea

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Enteral feeding

• Prevents atrophy of intestinal villi
• Prevents translocation of intestinal bacteria
• Prevents immunoglobulin A deficiency
• Usually causes diarrhea

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Overview

• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohns disease
• Issues in bariatric surgery

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Vitamin deficiencies

• Vit A - poor healing, skin keratosis, night
  blindness
• Vit D - osteomalacia
• Vit E - dystrophic changes of retina
• Vit K coagulopathy
• Thiamine (beri beri) lactic acidosis, altered
  mental status, DI, hyperbilirubinemia,
  thrombocytopenia
• Zinc - poor wound healing, impaired immunity
• Biotin - alopecia, neuritis, dermatitis
• Selenium - cardiomyopathy, hair loss, weakness
• Essential fatty acids - scaly dermatitis

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Causes of macrocytic anemia

• Dietary deficiency of B12
• Pernicious anemia (autoimmune destruction of
  gastric mucosa leading to a deficiency of
  intrinsic factor, which binds B12)
• Resection / bypass of stomach
• Resection / bypass of ileum
• Blind loop syndrome (bacterial overgrowth leads
  top competition for B12)

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Overview

• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohns disease
• Issues in bariatric surgery

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Crohns disease

• Diseased terminal ileum
• Poor uptake of vitamins A, D, E, K
• Vit D deficiency, when combined with frequent
  steroid use may lead to osteoporosis
• Important to avoid multiple SB resections to
  prevent short gut. Strictuoplasty when possible.

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What is the etiology of nephrolithiasis in
patients with Crohns disease?

• Hypercalcemia
• Hyperuricosuria
• Hyperoxaluria
• Vitamin D deficiency
• Dehydration

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What is the etiology of nephrolithiasis in
patients with Crohns disease?

• Hypercalcemia
• Hyperuricosuria
• Hyperoxaluria
• Vitamin D deficiency
• Dehydration

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Oxalate stones

• Oxalate is normally bound by calcium
• However, due to a diseased TI, bile salts and
  thus lipids are not well absorbed. The
  intralumenal calcium binds with fat
  (saponification) instead of oxalate. Oxalate is
  then absorbed in the colon, leading to
  hyperoxaluria and stone formation when excreted
  from kidney

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What is the minimal length of SB needed to avoid
short-gut syndrome?

• 40 cm of any portion of small bowel
• 60cm with ileo-cecal valve
• 120cm with ileo-cecal valve
• 120cm without ileo-cecal valve

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What is the minimal length of SB needed to avoid
short-gut syndrome?

• 40 cm of any portion of small bowel
• 60cm with ileo-cecal valve
• 120cm with ileo-cecal valve
• 120cm without ileo-cecal valve

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Overview

• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohns disease
• Issues in bariatric surgery

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Bariatric surgery deficiencies

• Iron and calcium deficiency (both absorbed in
  duodenum)
• B12 deficiency (lack of IF from bypassed stomach)
• A, D, E, K deficiencies
• Thiamine deficiency (likely from prolonged
  emesis) - can cause Wernickes

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EXTRA-CREDIT

• Some ABSITE favorites

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The principle fuel for colonocytes is

• Butyrate
• Acetoacetate
• D-Glucose
• Glutamine
• Propionate

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The principle fuel for colonocytes is

• Butyrate
• Acetoacetate
• D-Glucose
• Glutamine
• Propionate

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Principle fuel for colonocytes

• Butyrate is the major short-chain fatty acid
• The colon relies on bacterial fermentation for
  production of SCFAs
• Colonic inflammation is seen in diversion colitis
  secondary to SCFA deficiency
• UC patients may have a relative SCFA deficiency,
  can treat w/ SCFA enemas

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Branched-chain amino acids are

• Useful in ESRD
• Useful in ESLD
• Useful in pts with COPD

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Branched-chain amino acids are

• Useful in ESRD
• Useful in ESLD
• Useful in pts with COPD

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Branched-chain amino acids

• Leucine, isoleucine, valine
• Only amino acids that do not require
  metabolization by liver
• They can also be oxidized by muscle
• May be used for patients with liver failure

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Glutamine is

• Primary fuel for small bowel
• Primary fuel for malignant cells
• Most abundant free amino acid in the body
• Synthesized by skeletal muscle
• A conditionally essential amino acid

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Glutamine is

• Primary fuel for small bowel
• Primary fuel for malignant cells
• Most abundant free amino acid in the body
• Synthesized by skeletal muscle
• A conditionally essential amino acid