Fluids and Electrolytes Flashcards by Rehman Hameed

IBW equation for males

50 kg + 2.3(inches over 60”)

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IBW equation for females

45.5 kg + 2.3(inches over 60”)

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sensible fluid losses are

a. immeasurable
b. measurable

b. measurable

(ex. urine, defecation, wounds)

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insensible fluid losses are

a. immeasurable
b. measurable

b. immeasurable

(ex. sweat, fluid through lungs)

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ADH, RAAS, and ANP are all regulated by what organ?

kidney

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ADH functions (2 of them)

-reduces diuresis
-increases water retention

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RAAS (renin-angiotensin aldosterone system) functions (2 of them)

-renin secretion
-sodium/water regulation (aldosterone)

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ANP (atrial natriuretic peptide) functions (2 of them)

-dec ADH release
-counteracts effects of RAAS

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isotonic fluid range

275 to 290 mOsm/L

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hypotonic fluid range

< 275 mOsm/L

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hypertonic fluid range

> 290 mOsm/L

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definition of osmolarity

measure of solute concentration

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total osmolarity equation

total osmolarity = osmolarity of IV solution + osmolarity of added electrolytes

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what is the clinical estimate (adults) for calculating MIVF?

30-40 mL/kg/day

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what is MIVF?

maintenance of IV fluids (normal amount needed over 24 hours)

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NS, 1/2 NS, D5W, lactated ringers, and balanced salt solutions are examples of

a. crystalloids
b. colloids

a. crystalloids

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albumin, hetastarch (Hespan), tetrastarch (Voluven), blood, and plasmanate are examples of

a. crystalloids
b. colloids

b. colloids

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true or false: colloids can be given as a maintenance fluid

false (never give as maintenance fluid)

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crystalloid solutions functions (2 of them)

-provide water and/or sodium
-maintain osmotic gradient between intravascular and extravascular compartments

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normal saline use in therapy (2 of them; slide 29)

-intravascular fluid replacement (resuscitation)
-sodium and/or chloride replacement

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true or false: normal saline (0.9% NaCl) is never a maintenance fluid

true

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1/2 NS use in therapy (1; slide 29)

-used for maintenance fluids (combination products)

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lactated ringers use in therapy (3 of them; slide 30)

-replacement of blood loss
-approximates human plasma
-resuscitation (trauma, burn, etc.)

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D5W use in therapy (3 of them; slide 30)

-free water replacement
-NOT a resuscitative fluid
-NOT a MIVF by itself

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balanced salt solutions are crystalloid solutions containing physiological levels of what 2 things?

-chloride -buffer solutions

3 examples of balanced salt solutions

-lactated ringers -normosol-R -plasma-lyte

colloid solutions functions (2 of them; slide 35)

-inc plasma oncotic pressure -move fluid from interstitial compartment to intravascular (plasma) compartment

colloids are plasma expanders and increase _____ _____

molecular weight

colloids are used selectively for volume expansion, intravascular repletion in _____ patients

symptomatic

colloid solutions are considered _____ line therapy for hypovolemic shock

second

true or false: blood is a colloid

true

clinical use of albumin 5%

hypovolemic or intravascularly-depleted patients

clinical use of albumin 25%

fluid and/or sodium restricted patients

1 unit of RBCs = approximately _____-_____ mL

230-350 mL

low hemoglobin is usually less than or equal to _____-_____ g/dL

7-8

1 unit of RBCs inc hemoglobin by approximately ___ g/dL

1 g/dL

most common MIVF

D5W + 1/2 NS + 20 mEq KCl/L

how much urine output is considered dehydration?

less than 0.5 mL/kg/hr

BUN/SCr ratio > ___ may mean dehydration

normal sodium range

135-145 mEq/L

what is the most common electrolyte disturbance in hospitalized patients?

hyponatremia (Na < 135)

pseudohyponatremia (isotonic) can be seen with __________ or __________

hypertriglyceridemia (TG > 1000); hyperproteinemia

most common cause of isovolemic hypotonic hyponatremia (highlighted on slide 70)

SIADH (syndrome of inappropriate ADH release)

3 drug classes that can cause SIADH (highlighted, slide 73)

-antipsychotics -carbamazepine -SSRIs (fluoxetine, sertraline) (NSAIDs too but not highlighted)

first line treatment of SIADH

free water restriction

__________ may be beneficial if 24-48 hours of free water restriction fails

vaptans

for treating hyponatremia, in most cases the goal is to avoid rise in serum sodium > ___ mEq/L/hr or no more than ___-___ mEq/L/day

0.5; 8-12 (for ex. if their sodium is at 120, 132 would be highest we would go up to)

clinical presentation for hypovolemia and hypervolemia?

hypovolemia -> dehydration hypervolemia -> fluid overload

hypovolemic hypotonic natremia treatment options (2 of them)

-hypertonic NaCl (3%) if symptomatic -isotonic NaCl (0.9%) if asymptomatic

isovolemic hypotonic hyponatremia treatment options (2 of them)

-furosemide and 3% NaCl if symptomatic -isotonic NaCl (0.9%) if asymptomatic and water restriction

hypervolemic hypotonic hyponatremia treatment options (2 of them)

-furosemide and judicious 3% NaCl if symptomatic -furosemide in asymptomatic

how many hours is considered acute hyponatremia?

< 48 hours

how many hours is considered chronic hyponatremia?

> 48 hours

what can develop in pts with acute symptomatic hyponatremia?

metabolic encephalopathy (cerebral edema i.e. brain swelling is common)

treatment of acute symptomatic hyponatremia: inc serum Na+ by ___-___ mEq/L/hr until symptoms resolve

1-2 mEq/L/hr (max inc of 8-12 mEq/L in first 24 hours; generally an inc of 4-6 is enough)

what can result if sodium is corrected too rapidly in acute symptomatic hyponatremia?

central pontine myelinolysis (diffuse demyelinating lesions)

rule of 8s

replace half of sodium deficit in 8 hours, then remaining deficit w/in 8-16 hours

hypernatremia is always associated with _____

hypertonicity

for hypovolemic hypernatremia, what can we use to restore hemodynamic status?

0.9 % NaCl (NS)

what do we do for hypovolemic hypernatremia once intravascular volume has been restored?

calculate free water deficit

two ways to provide free water

-D5W continuous infusion -enteral free water via feeding tube

how should free H2O deficit be corrected?

-give 1/2 of total deficit over 24 hours -give remaining 1/2 over next 24-48 hours -adjust as needed (goal is 0.5 mEq/L/hr dec in serum Na+)

normal potassium levels

3.5-5 mEq/L

factors affecting potassium (3 of them)

-Na/K ATPase pump -kidneys -arterial pH/acid-base status

hypokalemia cause (in bold, from slide 129)

magnesium depletion (Mg is cofactor for Na/K ATPase, need Mg for it to work)

treatment if potassium is 3.5-4 mEq/L

no therapy generally recommended

treatment if potassium is 3-3.4 mEq/L

-treatment debateable -PO potassium for pts w cardiac conditions

treatment if potassium is < 3 mEq/L

-PO preferred in asymptomatic -IV for symptomatic pts or those who can't take PO (always treat)

what potassium levels would we give IV potassium?

K+ < 2.5-3 (arrythmia or cardiac arrest if given too quickly)

IV potassium: what is the infusion rate without cardiac monitoring?

10 mEq/hr

IV potassium: what is the infusion rate w/ continuous cardiac monitoring?

-20 mEq/hr -40-60 mEq/hr if emergent w/ severe hypokalemia (e.g. during cardiac arrest)

we may see a peaked T wave within what range of potassium levels?

5.5-6 mEq/L

acronym for treating severe hyperkalemia (K+ > 7)

C A BIG K DROP

3 steps for treating severe hyperkalemia (K+ > 7)

1. antagonize the membrane actions 2. dec extracellular K+ conc 3. remove K from the body

"C A BIG K DROP" stands for

Calcium Albuterol Bicarb Insulin + Glucose Kayexalate/Lokelma Diuretics (furosemide) Renal unit for dialysis Of Patient (antagonize the membrane actions; dec extracellular K+ conc; remove K+ from the body)

chronic treatment option for severe hypokalemia

patiromer (Valtassa)

Patiromer (Valtassa) MOA

binds potassium in GI tract and dec its absorption

hypomagnesemia is often associated with what other two electrolyte's metabolisms?

calcium and potassium

PO treatment of hypomagnesemia in asymptomatic pts with Mg > 1 mg/dL (2 of them)

-milk of mag 5-10 mL PO QID -mag-ox 800 mg PO daily or 400 mg PO TID with meals

IV treatment of hypomagnesemia in symptomatic pts (or those who cannot tolerate PO)

-Mg 1-2 mg/dL -> 0.5 mEq/kg -Mg < 1 mg/dL -> 1 mEq/kg

how many mEq of Mg are in one gram?

8 mEq

organs involved in calcium metabolism (3 of them)

bone, kidneys, intestine

acute treatment of hypocalcemia: ___-___ mg elemental Ca2+ IV over 5-10 minutes

100-300

1 gram Ca chloride = how many grams of Ca gluconate?

3 grams (270 mg elemental Ca)

Ca chloride can be administered ___ ___ during code; Ca gluconate is preferred for ___ administration

IV push; PIV

Ca gluconate vs Ca chloride: Ca gluconate has a _____ percentage of elemental Ca2+, has _____ predictable inc in Ca2+ conc, and _____ risk for extravasation (necrosis)

lower; less; less

usual administration rate for calcium (acute treatment of hypocalcemia)

1 gm/hour

chronic treatment for hypocalcemia: how many grams/day of elemental Ca2+?

1-3 grams/day

chronic treatment of hypocalcemia also includes _____ _____ supplementation

vitamin D

normal phos range

2.5-4.5 mg/dL

mild to moderate hypophosphatemia range

1-2 mg/dL

severe hypophosphatemia is less than ___ mg/dL

1 mg/dL

oral treatment for mild to moderate (phos 1-2) hypophosphatemia

Phos-NaK -> 30-60 mMol/day in 2-3 divided doses (Fleets Phospho-Soda is another one, but I think it is discontinued)

IV phosphorus: Use KPhos when K+ < ___ mEq/L Use NaPhos when K+ greater than or equal to ___ mEq/L

4; 4

Phos replacement: 1 mMol NaPhos = ? + ? 1 mMol KPhos = ? + ?

1 mMol NaPhos = 1.33 mEq Na + 1.33 mEq Phos 1 mMol KPhos = 1.47 mEq K + 1.47 mEq Phos

for phos replacement, infuse IV doses no faster than ___ mMol/hr