Fluid Replacement

Question 1

Body water compostition

Answer 1

Infants (75-85%), adult men (50-60%), adult females (45-55%)

Question 2

Fluid type composition

Answer 2

intracellular (2/3), extracellular (1/3)- interstitial (3/4), Plasma (1/4)

Question 3

Maintenance requirements

Answer 3

Holliday-segar calculation- 100 mL/kg first 10 kg, 50 ml/kg first 10 kg, 20 ml/kg after; or estimate ~30 mL/kg

Question 4

Two major types of fluid

Answer 4

crystalloids- normal saline (.9%NaCl), half normal saline (.45% NaCl), lactated ringers, Dextrose 5% in H2O; Colloid- albumin, hetastarch, plasmanate

Question 5

Crystalloids

Answer 5

provide water and sodium to maintain the osmotic gradient between extravascular and intravascular spaces

Question 6

Normal saline

Answer 6

.9 % NaCl, isotonic, used most common for fluid replacement, resuscitation in septic pt, can be used to correct Na or Cl deficiencies

Question 7

1/2 Normal saline

Answer 7

.45% NaCl hypotonic, use for maintenance fluids for hypernatremic pt

Question 8

Lactate ringers

Answer 8

approximates human plasma regarding electrolyte concentration, used for replacement of blood loss, mainstay in laboring women

Question 9

D5W

Answer 9

used for free water replacement, not a resuscitative fluid, various concentrations; 5g dextrose in 100 ml, given in liters so there is 50 g in dose

Question 10

NaCl 3%

Answer 10

hypertonic saline, rarely used for hypernatremia, inc ICP, dangerous! if not used appropriately, monitor very closely, give small volumes

Question 11

Never give what as IV fluids

Answer 11

sterile H2O, this is LETHAL

Question 12

Colloids

Answer 12

used to increase plasma oncotic pressure and move fluid from interstitial compartment to plasma compartment, use selectively for volume expansion during extreme situations like hemorrhagic shock

Question 13

Colloid options

Answer 13

albumin, blood, hetastarch

Question 14

Sodium

Answer 14

normal 135-145 mEq/L, extracellular cation needed to maintain cellular integrity and osmolar gradient to maintain fluid homeostasis throughout the different fluid compartments

Question 15

Hyponatremia

Answer 15

most commonly encountered electrolyte disturbance in hospitalized pts, associated w/ significant morbidity and mortality

Question 16

pseudohyponatremia

Answer 16

extreme elevations of lipid or proteins, osmolality is number of particles per liter H2O, measured serum osmolality is not sig affected, calc osmalitlity will be low

Question 17

hypertonic hyponatremia

Answer 17

RARE, serum [Na] falls by 1.6 mEq/l for each 100 mg/dL incremental increase in blood glucose; by correcting glucose you will correct hyponatremia

Question 18

hypotonic hyponatremia

Answer 18

more than 90% of cases, access ECF volume; hypovolemic, euvolemic, hypervolemic

Question 19

hypovolemic hyponatremia

Answer 19

dehydration, caused by diuretics and salt losing nephropathy, treat w/ IV fluids, hypertonic NaCl in symptomatic pts or isotonic NaCl in asymptomatic

Question 20

SIADH

Answer 20

syndrome of inappropriate antidiuretic hormone, water intake exceeds the capacity of the kidneys to excrete water, inability to concentrate urine

Question 21

Causes of SIADH

Answer 21

tumors, CNS disorders, head trauma, stroke, meningitis, pituitary surgery, DRUGS

Question 22

Drugs that induce SIADH

Answer 22

Despressin, oxytocin, carbamazepine, antipsychotics, TCAs, cyclophosphamides, chemo, NSAIDs, Morphine

Question 23

Isovolemic hyponatremia

Answer 23

will likely appear as euvolemic, slight increase in ECF, caused by glucocorticoid deficiency, hypothyroidism, psychogenic polydipsia, SIADH

Question 24

Treatment of isovolemic hyponatremia

Answer 24

furosemide +3% NaCL in symptomatic pts, isotonic fluids in asymptomatic pts, fluid restrictions (if correction needed quickly)

Question 25

Hypervolemic hyponatremia

Answer 25

total body water increased, seen in CHF, liver failure, renal failure, nephrotic syndromes

Question 26

Treatment of hypervolemic hyponatremia

Answer 26

furosemide and judicious use of 3% NaCl in symptomatic pts, furosemide in asymptomatic

Question 27

When treating hyponatremia, NEVER...

Answer 27

Correct faster than .5 mEq/L/hr or 12 mEq/L/day, it can cause osmotic demylenation

Question 28

Vasopressin receptor antagonists

Answer 28

Tolvaptan (Samsca), Conivaptan (Vaprisol)

Question 29

Tolvaptan (Samsca)

Answer 29

only available PO, given 10-60 mg daily, $$$

Question 30

Conivaptan (Vaprisol)

Answer 30

only available IV, CI, 20 mg IV load, then 20 mg infused over 24 hrs, $$$

Question 31

MOA of vasopressin receptor antagonists

Answer 31

promotes excretion of free water w/o loss of serum electrolytes resulting in net fluid loss, increased urine output, decreased urine osmoloality and restoration or normal serum Na levels

Question 32

Safety concerns w/ vasopressin receptor antagonists

Answer 32

risk of correcting too fast, must be initiated in hospital, must lift fluid restriction, most places only allow nephrologist to use

Question 33

Hypervolemic hypernatremia

Answer 33

caused by excessive hypertonic saline resuscitation, NaCHO3 administration, excessive table salt

Question 34

Treating hypervolemic hypernatremia

Answer 34

stop hypertonic fluids and give diuretics

Question 35

hypovolemic hypernatremia

Answer 35

treatment by restoring hemodynamic status first, can replace with NS even though the pt is hypernatremic

Question 36

Potassium

Answer 36

hypo and hyperkalemia associated w/ fatal arrythmias, each 1 mEq/L decrease in K

Question 37

factors affecting serum [K]

Answer 37

kidneys, arterial pH, insulin, B agonists, Na/K pumps

Question 38

hypokalemia caused by

Answer 38

diuretics, vomiting, NG drainage, magnesium depletion

Question 39

Goal for replacement in hypokalemia

Answer 39

4mEq/L, oral route preferred, less risk of overshoot; K= 3-3.9 mEq/L; 10 mEq K supplement will increase [K] by .1 mEq/L; K

Question 40

It is impossible to correct K if

Answer 40

mag is low, so correct mag first, then address K

Question 41

IV KCl

Answer 41

preferred if pt symptomatic or NPO, rate IV replacement limited if pt has only a peripheral IV (10 mEq/hr max), central IV can run at 20 mEq/hr, Dangerous!

Question 42

Hypokalemia w/ 3.2 mEq/L, not symptomatic

Answer 42

add 30 mEq KCl to IVF, or give 40 mEq PO q6hrs x3

Question 43

hypokalemia w/ 2.7 mEq/L and sympomatic

Answer 43

give KCl 40 mEq IV q4h x 3, and KCl liquid 40 mEQ PO x1 dose bolus

Question 44

Hyperkalemia

Answer 44

more consequential and more rare than hypokalemia, mild 5.5-6 mEq/L. mod 6-6.9 mEq/L, severe >7; some may not have symptoms if really high, still treat!

Question 45

Management of hyperkalemia

Answer 45

calcium gluconate (1 gm IVPx1 dose), Humulin R (10 units IVPx1), sodium bicarb 50 mEq IVPx1, albuterol (10 mg continuous neb), hemodialysis (4 hr session), sodium polystyrene (Kayexalate, 30 gm POx1); can do combo

Question 46

which management of hyperkalemia only stabilizes pericardium, inc threshold

Answer 46

calcium gluconate

Question 47

Which management of hyperkalemia has to be given w/ dextrose and works quickly?

Answer 47

Humulin R

Question 48

which management of hyperkalemia works quickly by driving K back into the cells

Answer 48

sodium bicarb and albuterol

Question 49

which management of hyperkalemia has fastest onset

Answer 49

hemodialysis

Question 50

which management of hyperkalemia has slower onset, works by a resin exchange of Na for K

Answer 50

sodium polystyrene

Question 51

Magnesium

Answer 51

needed for stabilizing macromolecule structures such as DNA/RNA and related to Ca and K metabolism; regulated by intake and kidney excretion

Question 52

Hypomagnesemia

Answer 52

associated w/ disorders of the GI tract or kidneys, decreased intestinal absorption, can be caused by chronic EtOH, amphotericin, diuretics, aminoglycosides

Question 53

Treatment of hypomagnesemia

Answer 53

asymptomatic- PO, milk of mag, or mag ox, will cause diarrhea; symptomatic- IV mag sulfate, 1 gram Mag sulfate= 8 gEq magnesium, infuse each gram over 1 hour, exceeding this results in renal excretion (level 1-2 give .5 mEq/kg, if

Question 54

Calcium, organs involved w/ metabolism

Answer 54

bone, kidneys, intestines

Question 55

hypocalcemia

Answer 55

correct for albumin, accounts for protein binding, if low albumin likely have norm Ca; if mag low fix that first

Question 56

hypocalcemia treatment

Answer 56

100-300 mg Ca IV over 10 mins, 1 g CaCl or 2-3 g Calcium gluconate

Question 57

Difference in CaCl and gluconate

Answer 57

CaCl contains more Ca, harder on veins; CaGL contains less Ca, easier on veins

Question 58

Hypercalcemia

Answer 58

seen in CA pts and hyperparathyroidism, caused by dec renal elimination, inc bone resorption, inc GI absorption

Question 59

Hypercalcemia tx

Answer 59

calcitonin, most common, loop diuretic, short term (lasix inc urinary excretion), bisphosphonates- pamidronate (Aredia-IV infusion over several hours, short term only, very effective)

Question 60

Phosphorus

Answer 60

critical for protein, fat and carb metabolism, modulates O2 carrying capacity of hemoglobin

Question 61

hypophoshatemia

Answer 61

1mmol=1.33 mEq sodium and 1.47 Eq potassium, replace orally or enteraly w/ neutra phos packet or Kphos tab q6-8h, also NaPhos/Kphos parenterally

Question 62

Hypophoshatemia levels/treatment

Answer 62

mild (2.3-3 mg/dL)- .32 mM/kg q4-6h; mod (1.6-2.2 mg/dL)- .64 mM/kG q4-6h; severe (