IVF and Diuretics Flashcards
How much sodium is in one level teaspoon?
5 mg of salt (NaCl)
~2 grams of sodium
What is a normal plasma BUN?
10-20
What is a normal blood creatinine?
around 1.0
What is a normal blood glucose?
60-100
What are the types of IVF?
D5 water
Normal Saline (0.9%)
half normal saline
lactated ringers
Why can’t IVF just be water?
the infusion of such a hypotonic solution could cause cell lysis
What is the equation for serum osmolality? What is the normal range?
2*Na + BUN/2.8 + Glucose/18
normal range is 285-295
What are the components of D5W? How is this distributed in the body?
50 gm of dextrose in 1 liter of water = 50 gm/L (5% dextroes)
osmolarity of 278
sugar is metabolized, leaving only the water, which is distributed according to body water (333 ML in ECF and 667 mL in ICF)
ultimately <100 mL is left in the plasma (3/4 extravascular)
What are the components of normal saline? How is this distributed in the body?
close to isotonic with serum
contains 9 gm of sodium chloride in 1 L (0.9%)
has osm of 308 (154 mEq of Na and 154 mEq of Cl)
1000 mL in the ECF and 0 mL in the ICF
ultimately 250 mL in the plasma
What are the components of half-normal saline? How is this distributed in the body?
1/2 of normal saline, 4.5 g/L (0.45%)
667 mL in ECF and 333 mL in ICF
ultimately 167 mL remains in the plasma
What are the components of lactated ringers? How is this distributed in the body?
contains 130 g/L of sodium and 109 g/L chloride
also contains 4 mmol/L potassium, 3mmol/L calcium, and 28 mmol/L lactate
900 mL ends up in the ECF and 100 mL in the ICF
ultimately ~225 mL in the plasma
What are the daily water maintenance requirements for a patient who is NPO?
100 cc/kg for the first 10 kg
50 cc/kg for the next 10 kg
20 cc/kg for every kg over 20
therefore, a 70 kg person would need 1000 + 500 + 1000 = 2500 mL/day
When is normal saline a good choice?
in patients who are volume deplete - provides sodium and chloride the kidney needs to maintain volume
diuresis vs. natriuresis
diuresis produces more urine
natriuresis promotes salt excretion
What are the classes of diuretics?
proximal tubule
distal convoluted tubule
loop diuretics
K+ sparing diuretics
proximal tubule diuretics
acetazolamide is the main diuretic here
inhibits the activity of carbonic anhydrase, promoting the absorption of HCO3-
interferes with sodium absorption by inhibiting the HCO3-/Na+ pump
leads to loss of both sodium and bicarbonate - used for diuresis in the setting of metabolic alkalosis
weak diruetic because the rest of the kidney can compensate
causes a non-gap acidosis
loop diuretics mechanism and uses
furosemide (Lasix), torsemide (Demadex), bumetanide (Bumex)
inhibits the Na+-K+-2Cl- symporter in the thick ascending limb of the loop of Henle
used for volume overload (rapid diuresis)
used for HTN particularly in chronic kidney disease
can also be used with normal saline to treat hypercalcemia
side effects of loop diuretics
fluid and electrolyte imbalances - hypokalemia, hypocalcemia, and hypomagnesemia
volume depletion
ototoxicity
hyperuricemia
hyperglycemia
increased LDL and triglycerides
thiazide diuretics mechanism and uses
hydrochlorothiazide (HCTZ), chlorthalidone, metolazone
inhibits the Na-Cl symporter in the distal convoluted tubule
show to decrease cardiovascular morbidity and mortality in HTN (low doses that do not cause hypokalemia)
a first line treatment option for hypertension
can also be ued to treat/prevent kidney stones
side effects of thiazide diuretics
impotence
fluid and electrolyte imbalances - hypokalemia, hyponatremia, hypercalcemia
impaired glucose tolerance
increased cholesterol
K+ sparing diuretics mechanism and uses
triamterene, amiloride, spironolactone, eplerenone
triamterene and amiloride inhibit the renal epithelial Na+ channels in the late distal tubule and collecting duct
spironolactone and eplerenone antagonize the mineralocorticoid receptor on epithelial cells in the late distal tubule and cortical collecting duct
used to avoid hypokalemia, use caution if at risk for hyperkalemia, good for hypertension
