Flashcards in Chapter 10: Nutrition Deck (120):
Approximately 20-25 cal/kg/d
4 calories / gram
Calories/gram: oral carbohydrates
4 calories / gram
3.4 calories / gram
Nutritional requirements for average healthy male
- 20% protein calories (1g protein/kg/d; 20% should be essential amino acids)
- 30% fat calories - important for essential fatty acids
- 50% carbohydrate calories
% kcal requirement increase: trauma, surgery, or sepsis
20% - 40%
kcal/day requirement: pregnancy
300 kcal / day
kcal/day requirement: lactation
500 kcal / day
Calculation: calorie requirement in burns
25 kcal/kg/d + (30 kcal/d x % burn)
Calculation: protein requirement in burns
1-1.5 g/kg/d + (3g x %burn)
What is much of energy expenditure used for?
How does fever affect basal metabolic rate?
Fever increased BMR 10% for each degree above 38.0 degrees Celsius
Calculation: caloric need in obesity
Weight = [(actual weight - ideal body weight) x 0.25] + IBW
Calculates basal energy expenditure based on weight, height, age, and gender
Glucose goals central line TPN
- Maximum glucose administration -> 3 g/kg/h
Fat based central nutrition
Peripheral line parenteral nutrition (PPN) - fat based
Fuel for colonocytes
Short-chain fatty acids (e.g., butyric acid)
Fuel for small bowel enterocytes
- MC amino acid in bloodstream and tissue
- Releases NH4 in kidney, thus helping with nitrogen excretion
- Can be used for gluconeogenesis
Primary fuel for most neoplastic cells
Normal protein level
6.0 - 8.5
Normal albumin level
3.5 - 5.5
Acute indicators of nutritional status
Retinal binding protein.
Ideal body weight:
- Men = 106lb + 6lb for each inch over 5ft
- Women = 100lb + 5lb for each inch over 5 ft
Preoperative signs of poor nutritional status
- Acute weight loss > 10% in 6 months
Strong risk factor for morbidity and mortality after surgery
Low albumin (
Ratio of CO2 produced to O2 consumed
Respiratory quotient - measurement of energy expenditure
Def: RQ > 1
Tx: decreased carbohydrates and caloric intake.
- High carbohydrate intake can lead to CO2 buildup and ventilator problems
Ketosis and fat oxidation (starving)
- Tx: increased carbohydrates and caloric intake
RQ: pure fat utilization
RQ = 0.7
RQ: pure protein utilization
RQ = 0.8
RQ: pure carbohydrate utilization
RQ = 1.0
Post op: diuresis phase
Post op days 2-5
Post op: catabolic phase
Post op days 0 -3
RQ: pure carbohydrate utilization
RQ = 1.0
What is the degree of injury proportional to?
The magnitude of metabolic response
When does glycogen deplete?
Depleted after 24-36 hours of starvation on (2/3 in skeletal muscle, 1/3 in liver) -> body then switches to fat.
Where is glucose-6-phosphatase found?
Only in the liver.
None in skeletal muscle: G6P stays in muscle after breakdown from glycogen and is utilized.
Gluconeogenesis precursors (x4)
Amino acids (esp alanine).
Simplest amino acid precursor for gluconeogenesis.
- Primary substrate for gluconeogenesis
Only amino acids to increase during times of stress
Alanine and phenylalanine
Where does gluconeogenesis occur in late starvation?
Why do protein-conserving mechanisms not happen after trauma?
Secondary to catecholamines and cortisol.
Main source of energy in starvation and in trauma
- In trauma, energy is more mixed (fat and protein)
% weight loss: pt can tolerate without complications
When do you consider Dobhoff tube or TPN?
After about 7 days without eating.
Why do you want to feed gut?
To avoid bacterial translocation (bacterial overgrowth, increased permeability due to starved enterocytes, bacteremia) and TPN complications
Consider when regular feeding not possible (e.g., CVA) or predicted to not occur for > 4 weeks
Utilizes ketones with progressive starvation (normally uses glucose)
Obligate glucose users
Red blood cells.
White blood cells.
- Occurs when feeding after prolonged starvation / maturation.
- Results in decreased K, Mg, PO4-.
- Causes cardiac dysfunction, profound weakness, encephalopathy.
How do you prevent referring syndrome?
10 - 15 kcal/kg/d
- Anorexia, weight loss, wasting
- Thought to be mediated by TNF-alpha
- Glycogen breakdown, lipolysis, protein catabolism
gram protein = gram nitrogen
6.25g protein = 1g nitrogen
Calculate nitrogen balacne
([protein/6.25] - [24hr urine N + 4g])
More protein ingested than excreted (anabolism)
Positive N balance
More protein excreted than taken in (catabolism)
Negative N balance
g/d: total protein synthesis for a healthy, normal 70kg male
- Responsible for amino acid production and breakdown
- Urea production is used to get rid of ammonia from amino acid breakdown
Amino acids: majority of protein breakdown from skeletal muscle
Glutamine and alanine
Broken down by pancreatic lipase, cholesterol esterase, and phospholipase to micelles and free fatty acids
Triacylglycerides (TAGs), cholesterol, and lipids
Aggregates of bile salts, long-chain free fatty acids, and monoacylglycerides
- Enter enterocyte by fusing with membrane
Increase absorption area for fats, helping form micelles
Used to synthesize bile salts
Fat soluble vitamins, absorbed in micelles
A, D, E, K
Enter enterocyte by simple diffuse
Medium and short chain fatty acids
Composition of chylomicrons
10% phospholipids / proteins / cholesterol
Where do chylomicrons go after they are formed (form micelles and other fatty acids when they enter the enterocytes)?
Lymphatics by way of the thoracic duct
Enter lymphatics along with chylomicrons
Long-chain fatty acids
Fatty acids: enter the portal system (same as amino acids and carbohydrates)
Medium- and short-chain fatty acids
On endothelium in liver and adipose tissue; clears chylomicrons and TAGs from the blood, breaking them down to fatty acids and glycerol
On endothelium in the liver and adipose tissue; binds short and medium-chain fatty acids
Free fatty acid-binding protein
Used for fuel by cardiac and skeletal muscles
Saturated fatty acids
Preferred source of energy for colonocytes, liver, heart, and skeletal muscle
Fatty acids (ketones - acetoacetate, beta-hyroxybutyrate)
Used as structural components for cells
Unsaturated fatty acids
In fat cells; breaks down TAGS (storage form of fat) to fatty acids and glycol, which are released into the bloodstream; sensitive to growth hormone, catecholamines, glucocorticoids
Hormone-sensitive lipase (HSL)
Essential fatty acids
- Needed for prostaglandin synthesis (long-chain fatty acids)
- Important for immune cells
Essential fatty acids (linolenic, linoleum)
What does carbohydrate digestion start with?
Begins with salivary amylase, then pancreatic amylase and disaccharidases
Carbs: absorbed by secondary active transport; released into portal vein
Glucose and galactose
Carbs: facilitated diffusion, released into portal vein
Fructose + glucose
Galactose + Glucose
Glucose + Glucose
What does protein digestion begin with?
Stomach pepsin, then trypsin, chymotrypsin, and carboxypeptidase
Released from pancreas and activated by enterokinase, which is release from the duodenum
What releases enterokinase?
- Activates pancreatic protein enzymes
- Can auto activate other trypsinogen molecules
Broken down to amino acids, dipeptides, and tripeptides by proteases
How is protein absorbed?
Secondary active transport
Where are free amino acids released after protein digestion?
Into portal vein
Why limit protein intake in liver and renal failure?
To avoid ammonia buildup and possible worsening encephalopathy
Branched chain amino acids
Leucine, isoleucine, valine ("LIV")
- Metabolized in muscle
- Possibly important in patients with liver failure
- Are essential amino acids
Branched-chain amino acids (LIV: leucine, isoleucine, valine)
Essential amino acids
Leucine, isoleucine, valine, arginine, histidine, lysine, methionin, phenylalanine, threonine, and tryptophan
General composition TPN
-10% amino acid
-Electrolyes (Na, Cl, K, Ca, -Mg, PO4, Acetate)
-Mineral and vitamine
-Lipids (given separately from TPN)
Hyperglycemia, encephalopathy, neuropathy
Poor wound healing
Weakness (failure to wean off ventilator), encephalopathy, decreased phagocytosis
Deficiency: Thiamine (B1)
Wernicke's encephalaopthy, cardiomyopathy
Deficiency: Pyridoxine (B6)
Sideroblastic anemia, glossitis, peripheral neuropathy
Deficiency: Cobalamin (B12)
Megaloblastic anemia, peripheral neuropathy, beefy tongue
Megaloblastic anemia, glossitis
Pellagra (diarrhea, dermatitis, dementia)
Deficiency: Essential fatty acids
Dermatitis, hair loss, thrombocytopenia
Deficiency: Vitamin A
Deficiency: Vitamin K
Deficiency: Vitamin D
Rickets, osteomalacia, osteoporosis
Deficiency: Vitamin E
Glucose is utilized and converted to lactate in muscle