Nutrition Flashcards
Baseline daily calorie requirement
20-25 kcal/kg/d
Baseline daily protein requirement
1g/kg/d
Fat % of caloric intake
30%
Protein % of caloric intake
20%
Carb % of caloric intake
50%
kcal of protein per gram
4kcal/g
kcal of fat per gram
9kcal/g
kcal of carb per gram
4kcal/g
Harris-Benedict equation for BMR (basal metabolic rate)
M: (10 x wt in kg) + (6.25 x ht in cm) - (5 x age) + 5
W: (10 x wt in kg) + (6.25 x ht in cm) - (5 x age) - 161
Caloric requirement after trauma, surgery, or sepsis
25-30 kcal/kg/d
Caloric requirements after burns
25 kcal/kg/d + (30 kcal/d x % burn)
Protein requirement after burns
1 g/kg/d + (3 g/d x % burn)
Predicted increase in caloric requirements due to elective surgery
1.2x
Predicted increase in caloric requirements due to multisystem trauma
1.3-1.5x
Predicted increase in caloric requirements due to sepsis
1.5-1.8x
Predicted increase in caloric requirements due to burns
1.5-2.0x
What is body’s state after surgery or critical illness
Catabolic state
Proteolysis, inadequate intake results in body turning to protein sources
Protein requirement for critically ill patient
1.5 g/kg/d
Protein requirement for head injury or burn patient
2 g/kg/d
Protein sparing effect
Delivery of small amount of carbs or fat (~400kcal/d) decreases proteolysis
Cause of insulin resistant during starvation
Inhibition of glucose oxidation. Increased gluconeogenesis causing hyperglycemia
Blood glucose goal during surgery
140-180 mg/dL
Benefits of enteral nutrition
stimulates IgA, prevents bacterial translocation, preserves upper respiratory tract, lessens inflammatory response
Timing for enteral feeding after admission/surgery
24-48 hours
Situations where enteral feeding is contraindicated
- Bowel perf
- obstruction
- Discontinuity
- Significant HD instability on pressors
When to start parenteral nutrition
after 7 days without nutrition and inability to tolerated enteral nutrition
Respiratory quotient
if elevated, makes weaning off the vent more challenging due to extra carbon dioxide made that must be expired (increased respiratory rate)
ratio of CO2 produced and oxygen consumed
measure of energy expenditure
Complications with parenteral nutrition
- Electrolyte disturbances (refeeding syndrome)
- Liver dysfunction (steatosis, cholestasis)
- Line infection
- GI dysfunction (mucosal atrophy from disuse, loss of brush border enzymes, bacterial overgrowth, decreased gut immunity)
Nitrogen balance
helps determine balance of anabolism and catabolism. Positive nitrogen balance is ideal –> pt getting enough protein
(Protein intake / 6.25) - (UUN + 4)
6.25g of protein in 1g nitrogen
UUN = 24-h urine urea nitrogen
Fat utilization respiratory quotient
0.7
protein utilization respiratory quotient
0.8
carb utilization respiratory quotient
1.0
RQ > 1
Overfeeding/Lipogenesis
Excess carbs
RQ < 0.7
Starvation/Ketosis & fat oxidation
Markers for long-term nutrition
Albumin
Transferrin
Markers for short-term nutrition
Prealbumin
Retinol-binding protein
Half life of albumin
20 days
Half life of prealbumin
2 days
Half life of transferrin
10 days
Half life of retinol-binding protein
12 hours
Most accurate marker of nutritional status in stable patients
Albumin
Respiratory quotient
CO2 produced / O2 consumed
Nitrogen balance equation
Total protein intake (g) / 6.25 - UUN + 4g
Urinary urea nitrogen (UUN)
Nitrogen lost in urine in 24 hours
Upper esophageal sphincter
Open/relaxes w/ swallowing, allows entry of food bolus into esophagus
Lower esophageal sphincter
Open/relaxes w/ swallowing, allows entry of food bolus into stomach
Mechanics above food bolus
contraction of circular smooth muscle layer squeezes bolus forward
Mechanics below food bolus
contraction of longitudinal smooth muscle layer widens lumen to receive bolus
Stomach wall mechanics
Muscularis externa (3 layers: circular, longitudinal, oblique) contraction helps break food into smaller bits Inner lining: simple columnar epithelium with goblet cells, secrete mucus longitudinal folds (rugae): allows stomach to increase storage capacity
Vent volumes decrease after placement of NGT placed to suction
Means NGT was placed nasotracheal position.
Remove NGT
Obstruction after feeding tube placement
Balloons migrate distally to obstruction
Buried Bumper Syndrome
Complication after PEG placement, bumper is overgrown by hypertrophic gastric mucosa, embedded into gastric wall
Likely secondary to enforced tightening of PEG causing an ulcer
Can’t see bumper endoscopically
Indications of Buried Bumper Syndrome
PEG tube can’t be mobilized, secretion along tube, upper ABD pain
MC causes of new-onset feeding intolerance
Gastroparesis (assoc w/ DM, PNA, sepsis)
Ileus
Sepsis/Infections
Tx of gastroparesis
prokinetic agents (metoclopramide, erythromycin) NJ tube feeds
Results of excessive protein
azotemia, hypertonic dehydration, hyperammonemia, metabolic acidosis
MC assoc w/ undernutrition
Enteral feeding
MC assoc w/ overfeeding
TPN
Components of TPN
amino acids, lipids, dextrose, trace elements, vitamins, electrolytes
Risk of DVT w/ CVC placement
Fem > IJ > SC
Dx of Hyperosmolar hyperglycemia state (HHS)
Glucose > 600mg/dL Osmolality >320 mOsm/kg Profound dehydration pH > 7.4 Bicarb > 15 mEq/L Ketonuria and Low ketonemia BUN > 30 mg/dL Creat > 1.5 mg/dL
Relative insulin deficiency but no ketosis due to presence of insulin inhibiting hormone-sensitive lipase mediated fat tissue breakdown
NUTRIC Score
APACHE II score SOFA score Comorbidities IL-2 # ICU admissions
Score >6 assoc w/ higher mortality, acquire more aggressive therapy
Immunonutrients
Arginine Glutamine Branched-chain amino acids omega-3 fatty acids nucleotides
Arginine
Precursor of polyamides, nucleic acids, amino acids involved in connective tissue synthesis, nitric oxide
Secretagogue for growth hormone, prolactin, insulin
Increases # T cells, enhances T-cell function
Improves wound healing
Increases mortality in septic elderly men
decreases risk of postop infxn, improves wound healing in pts with GI malignancy undergoing elective surgery
Glutamine
Most prevalent AA in human body
Made in skeletal muscle
Precursor of purines, pyrimidines, nucleotides, amino sugars, glutathione
Most important substrate for renal ammoniagenesis
Protects structural and functional integrity of intestinal mucosa
Maintains, augments cell immune functions
Branched-chain amino acids
Precursor of glutamine
Omega-3 fatty acids
Antagonize production of inflammatory eicosanoids from arachidonic acid
precursor of alternative family of eicosanoids
Anti-inflammatory
prevents immunosuppression
Nucleotides
impair de novo synthesis in catabolic states
precursors of RNA/DNA
Protects structural and functional integrity of intestinal mucosa
Maintains or augments cell immune functions, especially those assoc w/ cell-mediated immunity
how many kcal in gram of carb
- 0 kcal/g (enteral)
3. 4 kcal/g (parenteral)
Gold standard for determining resting energy expenditure in hospitalized patients
Indirect calorimetry
Long-chain fatty acids (LCFAs)
12+ carbons
Undergo esterification inside enterocytes, enter circulation through lymphatics as chylomicrons
Short-chain fatty acids (SCFAs)
Enter directly into portal circulation, transported into liver by albumin carriers
Made in colon by action of bacteria.
Substrates for colonocytes
Pts w/ colostomy and distal rectal pouches might develop diversion colitis in distal rectal pouch b/c lack of SCFAs as nutrition in mucosa. Tx w/ SCFAs enemas
Fuel source for stomach, enterocytes, pancreas, spleen
glutamine
fuel source for hepatocytes
amino acids
fuel source for colonocytes
SCFA (butyrate, acetate)
fuel source for cardiac myocytes
SCFA
fuel source for skeletal myocytes, brain, kidney
glucose
Fuel source for peripheral nerves, adrenal medulla, RBCs, PMNs
glucose
Fuel source for neoplastic cells
Glutamine, glucose
Omega 3 FAs
Found in fish
Modulate leukocyte function, regulate cytokine release via nuclear signaling and gene expression
Eicosapentanoid acid (EPA) Docosahexaenoic acid (DHA)
metabolized into prostaglandins called resolvins and neuroprotectins
Omega 6 FAs
Found in safflower oil, corn, cottonseed, soybean oil
assoc w/ higher inflammatory response
precursors to leukotrienes, thromboxane, prostaglandins (vasoconstrictive, induce platelet aggregation)
Vit A deficiency
Xerophthalmia, rashes
Vit A excess
Nausea, vomiting, brain edema, hepatomegaly
Vit D Deficiency
Hypocalcemia, hypophosphatemia
Vit D excess
Confusion, polyuria, polydipsia, vomiting, muscle weakness
Vit E deficiency
hemolytic anemia, neuromuscular disorders
Vit E excess
possible platelet dysfunction, inhibit wound healing
Vit K deficiency
Elevated INR, coagulopathy
Vit K excess
hemolytic anemia, kernicterus
Refeeding syndrome
D/t conversion of fat -> carb metabolism
hypophosphatemia
Beneficial for wound healing in malnourished or immunosuppressed patients
Vit A - stimulates fibroplasia, collagen cross-linking, epithelialization. may reverse inhibitory effects of glucocorticoids on inflammatory phase of wound healing
Vit C
essential for wound healing, hydroxylation of lysine and proline in collagen synthesis
Vit C deficiency
Scurvy
Impaired wound healing