Maker Study Guide Week 3

most common use of fluids is to expand plasma volume in ___ states

hypovolemic

Fluids

correct electrolyte imbalances, hydrate, and calories

Crystalloids (hypertonic, isotonic, hypotonic)

small (salt/electrolyte) molecules that can diffuse freely through a semipermeable membrane

0.9% saline, lactated ringers, plasmalyte

isotonic

Tx: fluid resucitation

0.45% saline, D5W

hypotonic

Tx: maintenance, hypertonicity, hypoglycemia

3% saline

hypertonic

Tx: severe hyponatremia

Dehydration (hypertonicity)

loss of TBW producing hypertonicity

Volume depletion

deficit in ECF volume

Isotonic solutions (normal saline, lactated ringers, plasma-lyte) mainly expand ____

Interstitial fluid ECF

Normal saline (0.9)

-wide availability and low cost

-volume resuscitation and volume depletion

-slightly hypertonic (higher Na and Cl conc. compared to plasma)

-Risk of hyperchloremic acidosis in large quantities

Buffered isotonic solutions: lactated ringers and plasma-lyte

more physiologic Na/Cl concentrations for fluid resuscitation and volume depletion

Hypotonic: D5W

Mechanism: Once glucose is metabolized, free water remains (hypotonic solution), which expands intracellular volume

D5W treats

hypernatremia and hypertonicity, provides limited nutrition

Avoid in critical ill and hypovolemic patients

Hypertonic solutions (3%, 5%, 23.4% saline) expands _____ and allows ___

ECF, volume resuscitation with relatively small volumes

Colloids mainly expand the _____

plasma volume/part of ECF

Albumin (5%/25%)

most commonly used colloid

5% albumin

isosmotic with plasma

1L of 5% albumin will increase ECF by ___, and is used in ___

1L, plasmapheresis/volume deficit

25% albumin

hyperoncotic

1L of 25% albumin will increase ECF by ___, and is used in ___

4L, oncotic deficit

Effects of Crystalloids and Colloids on ECF

-Crystalloids spread throughout ECF

-Colloids (ex. albumin) stay in the blood vessels and increase plasma volume more.

Plasma volume (1/3 ECF)

intravascular IN BLOOD VESSEL

Interstitial volume (2/3 ECF)

fluid surrounding cells outside blood vessels

Sodium (Na+) normal range

135-145 mEq/L

Na+ is the main cation in the ___ and determines ___ with H2O

ECF, ECF volume

Na+ is the primary factor in

establishing osmotic relationship between ICF and ECF

Always consider ___ and ___ in Na+ imbalance

sodium level and fluid status

Hypotonic hyponatremia

Hypovolemic: Na loss >> water loss

Euvolemic: water increases, no change in Na

Hypervolemic: Water gain >> Na gain

Hypertonic hyponatremia tx

hyperglycemia management

MoA: excess glucose -> diffusion of water from ICF to ECF -> serum Na dilution

Calculate corrected Na: every 100 mg/dL increase in glucose >100 mg/dL, Na decreases by 1.6 mEq

Acute/Severely Symptomatic Hypotonic Hyponatremia Pointers

Severe CNS symptoms

-max rate of correction: N/A exceed 8-12 mEq/L in 24hr

Tx: 3% saline (Na target~120 mEq/L)

-Concurrent volume overload present: add loop diuretic to increase water excretion

Tx of hyponatremia should occur ____ due to risk of osmotic demyelination syndrome (brain damage)

SLOWLY.

euvolemic hyponatremia (SIADH focus)

water increases, no change in Na+

SIADH secretion mechanism

impaired water excretion due to inability to suppress secretion of ADH

concentrated urine -> water retention -> increased TBW -> decreased plasma Na by dilution

Tx overview of SIADH: Non emergency Cases

1) Fluid restriction <1L/day. FIRST LINE

2) Oral salt tabs + loop diuretic (lowers urine oSm) 2ND LINE

Urea-Na (Induces osmotic diuresis)

3) Conivaptan (Vaprisol)-IV, Tolvapatan (Samsca)-PO

Tolvapatan: indicated for euvolemic/hypervolemic hypoNa despite fluid restriction

Hospital tx; risk of hepatotixicity (cirrhosis), BB warnings, MG

Tx overview of SIADH: emergency cases

1) hypertonic saline FIRST LINE (severe, acute disease) ICU only. greatest risk of overcorrection

Hypovolemic hyponatremia

Na loss >> water loss

tx: isotonic fluids; tx underlying cause

hypervolemic hyponatremia

Water gain >> sodium gain

tx: fluid (<1L/day) and Na (<1-2g/day) restriction

2nd line: Tolvaptan (if CHF)

tx underlying cause

Hypovolemic hypernatremia (decrease in water > decrease in Na)

1) causes

2) symptoms

3) Tx:

1) renal losses (osmotic diuresis, diuretics), inadequate fluid intake (elderly), GI losses (diarrhea, vomiting)

2) volume depletion (orthostasis, dry mucous membranes, dec skin turgor, elevated SCr/BUN, dec UOP)

3) H2O + Na depletion: isotonic fluids

H2O depletion: D5W

Euvolemic hypernatremia (decrease in water, no Na change)

1) causes

2) tx

1) DI

2) central: DDAVP/desmopressin

nephrogenic: HCTZ, indomethacin amiloride (Li-induced)

Hypervolemic hypernatremia (increase in Na> increase in H2O)

1) causes

2) tx

1) latrogenic Na administration (3% saline, Na bicarb, NaCl tabs)

2) D5W + loop diuretic

Do not correct serum Na by more than ___ in 24 hours

12 meq/L

K+ normal range

3.5-5 meq/L (homeostasis maintained by kidneys)

Hypokalemia Tx *caution in renal impairment

IV Tx: (EKG changes, <2.5 mEq/L)

KCl IV if EKG changes or severe hypokalemia (<2.5 mEq/L)

*high alert: reconstituted prior to dispensing

Oral Tx: OK if mild (2.5-3.4 mEq/L)

Potassium chloride (K-Tab, Klor-con)

Hyperkalemia

1) Causes

2) Symptoms

1) Renal failure, drugs (ACE Inhibitors/ARBS, K-sparing diuretics, beta blockers, calcineurin inhibitors)

2) EKG changes/arrhythmias >6 mEq/L, cardiac arrest if above 7 mEq/L

Hyperkalemia Tx

Ca2+ Cl-/gluconate IV : Raises cardiac threshold potential→ reverses EKG changes, NO effect on K+ levels

Furosemide: Increased K+ excretion

Regular insulin: stimulates Na/K ATPase → IC K+ redistribution, typically used for acute tx

Dextrose 50%: stimulates insulin release → intracellular K+ redistribution; given with insulin to prevent hypoglycemia

Na+ bicarbonate: intracellular K+ redistribution usually only given if pt has metabolic acidosis

Albuterol: stimulates Na/K+ ATPase → intracellular K redistribution; typically used or acute treatment

Hemodialysis: removal of K from serum

Sodium polystyrene sulfonate (Kayexalate): resin exchange Na+ for K+ in the gut → increased K+ excretion

Patiromer (Veltassa): Resin exchange Ca for K in the gut → increased K excretion

Sodium zirconium cyclosilicate (Lokelma): Resin exchange Na for K in the gut → increased K excretion

Hyperkalemia Tx that increases K+ excretion

1) Furosemide

Resin exchange mechanisms:

2) sodium polystyrene sulfonate (Kayexalate)

3) Patiromeer (Veltassa)

4) sodium zirconium cyclosilicate (Lokelma)

Hyperkalemia Tx that has no effects on K+

Ca2+ Cl-/gluconate IV : Raises cardiac threshold potential→ reverses EKG changes, NO effect on K+ levels

Hyperkalemia Tx that redistributes K+

regular insulin, dextrose 50%, Na+ bicarbonate, albuterol

Hyperkalemia Tx given for metabolic acidosis

sodium bicarb

Hyperkalemia tx given for acute condition

regular insulin and albuterol (stim of Na/K ATPase)

2 hyperkalemia tx given together to prevent hypoglycemia

insulin and dextrose 50%

Mg2+ normal range

1.7-2.3 mg/dL

Hypomagnesemia

1) Cause

2) Tx

1) Decreased GI intake or increased renal/GI losses

2) PO Therapy for Hypomagnesemia (Caution with renal impairment)

Preferred in mild/moderate deficiency (1-1.6 mg/dL) and asymptomatic. Magnesium oxide

Diarrhea-most common adverse effect.

IV Therapy for Hypomagnesemia (Caution with renal impairment)

Magnesium sulfate IV if severe deficiency (< 1 mg/dL) or symptomatic or NPO

Commonly, one time doses are given followed by repeat levels and re-evaluation

Hypermagnesemia tx

-IV calcium (same as with hyperkalemia) to reverse cardiotoxicity or EKG changes, IV loop diuretics + IV normal saline

-hemodialysis

A patient with impaired renal fxn has __ Mg and __ K

high, high

Phosphorus range

2.5-4.5 mg/dL

Hormonal control of phosphorus

PTH --> decreases Phos serum levels

Calcitrol --> increases Phos serum levels

PTH release

Phosphorus and Calcium Homeostasis:

Increases serum calcium and phosphorus levels

PTH is released when ____ is detected

low serum calcium

PTH raises calcium by acting on the

kidneys, bones, and indirectly SI

In the kidney, PTH

increases renal calcium reabsorption

In the bone, PTH

stimulates bone resorption (releases calcium and phosphorus)

In the small intestine, PTH

increases absorption of dietary Ca2+ and phosphorus

PTH activates vitamin D in the kidney, which is converted in the ____

liver to calcidol -> calcitrol the active form that increases intestinal calcium absorption

Hypophosphatemia

1) Oral Tx

2) IV Tx

1) MILD-MOD def.

Potassium phosphate and sodium phosphate

Product selection dependent on K and Na.

2) SEVERE (<1 mg/dL)

Sodium phosphate (mL), Potassium phosphate (mL)

*DO NOT MIX WITH Ca2+ containing fluids due to precipitation

Hypophosphotemia is caused by

dec GI intake/absorption

Hyperphosphatemia is caused by

renal failure.

Hyperphosphatemia tx

-dietary phosphorus restriction (recommended for pts with CKD, dialysis)

-phosphate binders (bind to sietary phosphprus in GI tract)

-hemodialysis (last resort, only if pt is alr on it)

Ca2+ normal range

8.5-10.5 mg/dL

ionized: 1.1-3.5 mmol/L (4.4-5.4 mg/dL)

Ca2+ hormonal control

Both PTH and calcitrol increases seru Ca level

Corrected Ca

Corr Ca = Measured Ca + [0.8 x (4 - Alb)]

Always use the corrected or ionized Ca in patients with ____

hypoalbuminemia

Hypocalcemia tx

PO: Calcium carbonate (highest amount of elemental Ca)

IV: Calcium chloride, calcium gluconate

Fake hypocalcemia

decreased albumin. be sure to calc Crcl

Tx of Hypercalcemia

0.9% saline: restoration of intravascular volume, increase in Ca excretion. First line therapy if acute tx

Loop diuretics: Furosemide. Increases Ca2+ excretion. Usually only used in conjunction with fluids.

Calcitonin (Miacalcin): inhibits bone resorption, promotes Ca excretion.

Steroids: decreases intestinal Ca2+ absorption. Many adv effects, bad long term.

Bisphosphonate: Zoledronate, Pamidronate, inhibits bone resorption, caution in pts with impaired renal functional first line for chronic malignancy-related disease

Calcimimetics: Ca2+ sensing receptor agonist, reducing PTH. Used primarily for secondary hyperparathyroidism in dialysis patients and parathyroid cancer

Hemodialysis: removal of Ca via dialysis. Rarely used unless patient on dialysis.

First line therapy in acute hypercalcemia

0.9% saline

Loop diuretics is used in _____ in hypercalcemia

conjunction with fluids

Bisphosphonate is

first line for chronic malignancy-related disease

Calcimimetics is used for

secondary hyperparathyroidism in dialysis patients and PTH cancer

NA disorders

consider fluid status and correct slowly

Mild-moderate hyperphosphatemia/hypocalcemia

chronic problem in CKD

K disorders

Tx: URGENT.

slight abnormalities usually monitored and not treated