nutrition: basic science lecture series
TRANSCRIPT
Nutrition
Basic Science Lecture Series
Umut Sarpel
8/11/05
Overview
• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohn’s disease
• Issues in bariatric surgery
Overview
• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohn’s disease
• Issues in bariatric surgery
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
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
Overview
• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohn’s disease
• Issues in bariatric surgery
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 > 1.0
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
a) 0.66
b) 0.7
c) 0.8
d) 0.9
e) 1.1
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
a) 0.66
b) 0.7
c) 0.8
d) 0.9
e) 1.1
Respiratory Quotient
• An RQ > 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
Overview
• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohn’s disease
• Issues in bariatric surgery
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
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
The primary source for glucose in early starvation (1week) comes from
a) Proteins in skeletal muscle
b) Ketone bodies
c) Free fatty acids
d) Glycogenolysis
e) Lipolysis / Acetyl CoA
The primary source for glucose in early starvation (1week) comes from
a) Proteins in skeletal muscle
b) Ketone bodies
c) Free fatty acids
d) Glycogenolysis
e) Lipolysis / Acetyl CoA
Glucose is the primary fuel source for all the following tissues except
a) Renal medulla
b) Brain tissue
c) WBCs
d) RBCs
e) Peripheral nerves
f) Heart
Glucose is the primary fuel source for all the following tissues except
a) Renal medulla
b) Brain tissue
c) WBCs
d) RBCs
e) Peripheral nerves
f) Heart
Overview
• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohn’s disease
• Issues in bariatric surgery
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
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
What is the maximum rate of glucose administration in TPN?
a) 1 gm/kg/hr
b) 5 gm/kg/hr
c) 10 gm/kg/hr
d) 15 gm/kg/hr
What is the maximum rate of glucose administration in TPN?
a) 1 gm/kg/hrb) 5 gm/kg/hrc) 10 gm/kg/hrd) 15 gm/kg/hr
Besides hyperglycemia, higher rates of glucose infusion can also cause vessel thrombosis
Overview
• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohn’s disease
• Issues in bariatric surgery
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 (<150cc)
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
Enteral feeding:
a) Prevents atrophy of intestinal villi
b) Prevents translocation of intestinal bacteria
c) Prevents immunoglobulin A deficiency
d) Usually causes diarrhea
Enteral feeding:
a) Prevents atrophy of intestinal villi
b) Prevents translocation of intestinal bacteria
c) Prevents immunoglobulin A deficiency
d) Usually causes diarrhea
Overview
• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohn’s disease
• Issues in bariatric surgery
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
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)
Overview
• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohn’s disease
• Issues in bariatric surgery
Crohn’s 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.
What is the etiology of nephrolithiasis in patients with Crohn’s disease?
a) Hypercalcemia
b) Hyperuricosuria
c) Hyperoxaluria
d) Vitamin D deficiency
e) Dehydration
What is the etiology of nephrolithiasis in patients with Crohn’s disease?
a) Hypercalcemia
b) Hyperuricosuria
c) Hyperoxaluria
d) Vitamin D deficiency
e) Dehydration
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
What is the minimal length of SB needed to avoid short-gut syndrome?
a) ~40 cm of any portion of small bowel
b) ~60cm with ileo-cecal valve
c) ~120cm with ileo-cecal valve
d) ~120cm without ileo-cecal valve
What is the minimal length of SB needed to avoid short-gut syndrome?
a) ~40 cm of any portion of small bowel
b) ~60cm with ileo-cecal valve
c) ~120cm with ileo-cecal valve
d) ~120cm without ileo-cecal valve
Overview
• Calorie / protein requirements
• Respiratory Quotient
• Effects of starvation
• Benefits / risks TPN
• Enteral feeding
• Vitamin deficiencies
• Crohn’s disease
• Issues in bariatric surgery
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 Wernicke’s
EXTRA-CREDIT
Some ABSITE favorites…
The principle fuel for colonocytes is
a) Butyrate
b) Acetoacetate
c) D-Glucose
d) Glutamine
e) Propionate
The principle fuel for colonocytes is
a) Butyrate
b) Acetoacetate
c) D-Glucose
d) Glutamine
e) Propionate
Principle fuel for colonocytes
• Butyrate is the major short-chain fatty acid
• The colon relies on bacterial fermentation for production of SCFA’s
• Colonic inflammation is seen in diversion colitis secondary to SCFA deficiency
• UC patients may have a relative SCFA deficiency, can treat w/ SCFA enemas
Branched-chain amino acids are
a) Useful in ESRD
b) Useful in ESLD
c) Useful in pts with COPD
Branched-chain amino acids are
a) Useful in ESRD
b) Useful in ESLD
c) Useful in pts with COPD
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
Glutamine is
a) Primary fuel for small bowel
b) Primary fuel for malignant cells
c) Most abundant free amino acid in the body
d) Synthesized by skeletal muscle
e) A conditionally essential amino acid
Glutamine is
a) Primary fuel for small bowel
b) Primary fuel for malignant cells
c) Most abundant free amino acid in the body
d) Synthesized by skeletal muscle
e) A conditionally essential amino acid