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55 Cards in this Set
- Front
- Back
explain the 60-40-20 rule for fluid compartments
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total body water is 60% of body weight
Intracellular fluid is 40% of body weight Extracellular fluid is 20% of body weight |
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Three reasons for oliguria
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low blood flow to kidney
kidney pathology post-renal obstruction |
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normal urine output in adults?
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>1mL/kg/hr
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for each degree celsius above 37C, how much extra insensible losses per day?
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100mL/day
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what is the standard maintenance fluid used?
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D5 1/2 NS +/- 20mEq KCl
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What portion of D5W remains intravascular? Why?
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1/12 because glucose freely permeates all fluid compartments and intravascular fluid space is only 1/12 of total body water
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100/50/20 rule for maintenance fluids
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100 mL/kg for first 10 kg, 50 mL/kg for second 10 kg, 20 mL/kg for every 1kg over 20kg
divide by 24 for hourly rate |
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4/2/1 rule for maintenance fluids
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4 mL/kg for first 10 kg, 2 mL/kg for second 10 kg, 1mL/kg for every 1 kg over 20
this is HOURLY estimation |
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pre-renal azotemia from hypovolemia - significant lab values?
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Increased serum Na, decreased urine Na, BUN/Cr >20:1, FeNa <1
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4 primary diseases that cause fluid-retention
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CHF, nephrotic syndrome, cirrhosis, ESRD
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hyponatremia + urine Na >20mmol/L =?
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salt-wasting nephropathy, diuretic overuse, or hypoaldosteronism
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hyponatremia + urine Na >40mmol/L suggests what condition?
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SIADH
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treatment of severe hypotonic hyponatremia (Na+ <110 mmol/L)? what is possible complication?
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hypertonic saline to increase Na+ 1 to 2 mEq/L per hour
risk of central pontine myelinolysis if increase >8mEq/L in 24 hours |
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one renal and one extra-renal cause of HYPOVOLEMIC HYPERNATREMIA
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renal: osmotic diuresis (commonly glycosuria)
extra-renal: diarrhea |
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common disorder causing ISOVOLEMIC HYPERNATREMIA
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diabetes insipidus
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CNS effects of Hypernatremia vs. Hyponatremia
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in hyponatremia, get CNS cell edema
in hypernatremia, get CNS cell dehydration |
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common causes of Hypervolemic Hypernatremia
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Cushing's syndrome, iatrogenic (too much parenteraly NaHCO3), glucocorticoids
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how to differentiate nephrogenic vs. central diabetes insipidus?
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Desmopressin challenge: if response to desmopressin, there is a CENTRAL process
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how to calculate FREE WATER DEFICIT?
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Total Body Water (1 - (actual Na+ / desired Na+))
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how is total calcium and free ionized calcium affected by Hypoalbuminemia?
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total calcium is decreased, free ionized calcium is unchanged
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how to calculate free ionized calcium?
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Total calcium - (serum albumin x 0.8)
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how does pH affect total calcium and free ionized calcium? why?
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increased pH causes DECREASED free ionized calcium by enabling albumin to bind more
i.e. in alkalemic states, total calcium is normal but free ionized calcium is LOW |
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three hormones involved in Calcium metabolism? what are their targets?
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hormones: PTH, Calcitonin, Vitamin D
targets: Kidney, Gut, Bone |
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PTH affects on Kidney, Gut, Bone?
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Kidney: inc. Calcium resorption, decreased phosphate resorption
Gut: activation of Vitamin D Bone: increased bone resorption |
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Calcitonin affects on Kidney, Gut, Bone?
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Kidney: decreased calcium resorption, increased phosphate resorption
Gut: decreased Calcium absorption Bone: dec. bone resorption |
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Vitamin D affects on Kidney, Gut, Bone?
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Kidney: inc. Calcium resorption, decreased phosphate resorption
Gut: Inc. calcium resorption, inc. phosphate resorption Bone: increased bone resorption |
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why SPECIFICALLY does renal insufficiency lead to hypocalcemia?
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decreased 1,25-Vitamin D
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what other value should be looked at when total Calcium is low?
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albumin - if low then this is why
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hypocalcemia should always be in the differential for what ECG finding?
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Prolonged QT
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acute pancreatitis can be associated with what electrolyte abnormality?
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hypocalcemia - calcium deposits in pancreas occur
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emergency treatment for symptomatic hypocalcemia
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IV calcium gluconate
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Barterr's syndrome: what is it?
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autosomal recessive defect in salt reabsorption in ascending limb --> juxtaglomerular apparatus hyperplasia --> inc. renin and aldosterone --> hypokalemia
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urine potassium cutoff to differentiate GI loss vs renal loss
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GI loss: <20mEq/L
Renal Loss: >20 mEq/L |
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Hypo kalmia predisposes patients to what drug toxicity?
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Digoxin
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what are hyperkalemias effects on ammonia?
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hyper kalmia inhibits renal ammonia synthesis and reabsorption leading to acidosis and more potassium release from cells
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at what value of hyperkalemia do ECG findings occur?
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6.0 mmol/liter
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ECG findings in hyperkalemia
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PEAKED T waves, prolonged PR, QRS widened and can fuse with T wave
in severe hyperkalemia: VFib and cardiac arrest |
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with hyperkalemia and ECG changes what is the first drug to administer?
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IV calcium gluconate to stabilize cell membranes
use CAUTION when administering to digoxin patients bc hypercalcemia predisposes to dig toxicity |
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largest reservoir of Magnesium in the body?
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Bone - two-thirds
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most common cause of Hypomagnesemia?
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malnutrition/steatorrheic states
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hypomagnesemia makes what other two electrolyte abnormalities difficult to treat?
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hypokalemia and hypocalcemia
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what two electrolyte abnormalities frequently (but not always) coexist with hypomagnesemia?
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hypokalemia and hypocalcemia
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ECG changes in hypomagnesemia?
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prolonged QT interval, T wave flattening, and in severe cases: Torsade de pointes
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treatment of Mild and Severe hypomagnesemia?
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mild: oral Mg2+ supplement (magnesium oxide)
Severe: parenteral Mg2+ (magnesium sulfate) |
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most common cause of HYPERmagnesemia?
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renal failure
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common signs of HYPERmagnesemia?
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loss of DTRs, somnolence --> coma, nausea, weakness
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ECG findings in HYPERmagnesemia?
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similar to hyperkalemia: increased PR interval, widened QRS complex, elevated T waves
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treatment of severe HYPERmagnesemia?
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first: administer IV calcium gluconate to stabalize cardiac cell membranes
saline, furosemide, dialysis (renal failure patients) |
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serum cutoffs for HYPO vs. HYPERphosphatemia
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HYPO: <2.5 mEq/L
HYPER: >5 mEq/L |
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two most common causes of hypophosphatemia?
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alcoholism and DKA
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most common cause of hyperphosphatemia?
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decreased renal excretion due to renal failure
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main clinically relevant finding in prolonged hyperphosphatemia?
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hi PO4(3-) in blood causes metastatic calcification and soft-tissue calcifications by crashing out of solution
HYPOCALCEMIA as sequela, leads to neurologic changes |
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how to predict if phosphate-calcium deposition will ocurr?
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(serum calcium x serum phosphorus) >70
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equation for Anion Gap?
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AG = [Na+] - ([Cl-] + [HCO3-])
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Normal range of Anion Gap?
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8 to 15
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