Electrolytes and Imbalances Flashcards
What 7 electrolytes are included in the “fish bone”?
(1) Na+
(2) Cl-
(3) BUN
(4) blood glucose
(5) K+
(6) HCO3-
(7) SCr
What is osmolality?
Concentration of solutes/electrolytes per liter of solution/water
What does increased serum osmolality suggest?
Volume depletion → inc [ ] of electrolytes
What does decreased serum osmolality suggest?
Volume overload → dilution of electrolytes
What is water regulation primarily controlled by?
Secretion of ADH
What is the mechanism of water regulation in the body?
Blood volume decreases→ pituitary releases ADH→ ADH tells the kidney to hold onto water
What is third spacing?
When there is a large volume of fluid from the intravascular compartment that shifts into an interstitial space
What are colloids?
Solutions that don’t cross the cell membrane b/c they’re too big→ remain in the intravascular compartment and expand the intravascular volume and draw fluid from extravascular spaces via higher oncotic pressure
What are crystalloids?
Solutions that contain small molecules that easily pass through the cell membrane and inc fluid volume in both interstitial and intravascular spaces
What is an isotonic solution?
Same concentration of solutes in blood so cell content stays the same (when you give, it doesn’t change the water content of the cell)
What is a hypotonic solution?
Same concentration of solutes in blood so cell content stays the same (when you give, it doesn’t change the water content of the cell)
What is a hypertonic solution?
Higher [ ] of solutes so solutions pull fluid from the cells-shrink
What are 3 examples of isotonic IV fluids?
(1) normal saline 0.9% NaCl
(2) lactated ringer
(3) ringers solution
When do you give normal saline?
When the extracellular volume is low (ex: dehydration, vomiting/diarrhea, shock, hemorrhage, etc.)
What isotonic solution most closely mimics the blood and plasma concentration?
Lactated ringers
What 5 electrolytes do lactated ringers contain?
(1) sodium (2) potassium (3) chloride (4) calcium (5) bicarb-lactate
What pts will benefit greatly from lactated ringers?
Pts requiring electrolyte replacement
What 4 types of pts should you avoid giving lactated ringers to?
(1) lactic acidosis
(2) liver disease
(3) renal impairment
(4) pH >7.5
What 4 electrolytes are in ringers solution?
(1) sodium
(2) chloride
(3) potassium
(4) calcium
In what 2 situations should you give ringers solution?
(1) when giving lactate is c/i
(2) in lactic acidosis
What is special about dextrose 5%?
It is isotonic, but when metabolized it becomes hypotonic and causes fluid to shift into cells (it also provides minimal cals while pt is NPO)
When are hypotonic IV fluids used?
Used to tx pts w/conditions causing intracellular dehydration (hypernatremia, DKA, hyperosmolar hyperglycemia)
What 3 things is sodium important for?
(1) regulates transmission of impulses in nerve and muscle fibers
(2) main factor in determining volume of extracellular space
(3) helps maintain acid-base balance
What are 5 conditions associated with hyponatremia?
(1) acute illness
(2) HF
(3) cirrhosis
(4) renal failure
(5) aggressive IV fluid administration
Excess of what can cause hyponatremia and what is the mechanism leading to hyponatremia?
Hyperglycemia→ high serum sugar→ cells release water → sodium gets diluted while body gets overloaded with water (body is trying to dilute the sugar by inc water, but that dilutes salt too causing hyponatremia)
What 3 things lead to hyponatremia?
(1) syndrome of inappropriate ADH
(2) chronic alcoholics
(3) water intoxication-marathon runners, drugs
How do you tx hyponatremia?
Tx depending on cause: if fluid overload→ fluid restriction, if severe and symptomatic→ fluid restriction + sodium replacement
Why do you want to correct hyponatremia slowly?
B/c of risk of Central Pontine Myelinolysis (CPM)- an osmotic demyelinating injury
What are 5 signs of hypernatremia?
(1) fever
(2) sweating
(3) vomiting
(4) diarrhea
(5) primary hypodipsia
What are the 2 mechanisms of diabetes insipidus causing hypovolemic hypernatremia?
(1) dec secretion of ADH (2) inc renal resistance to ADH (cannot [ ] urine); you’re peeing out the water, but Na+ is staying
What happens in hyperaldosteronism leading to hypernatremia?
Problem w/adrenals (usually a benign tumor) → excess production of aldosterone → sodium and water inc and potassium dec
What 2 things do you tx hypovolemic hypernatremia pts with?
(1) IV isotonic solution (0.9% saline)
(2) limit salt intake
What do you tx euvolemic hypernatremia pts with?
IV hypotonic fluids (D5W)
What 2 things do you tx hypervolemic hypernatremia pts with?
(1) D5W
(2) diuretics
What are the 3 most common causes of dyskalemia?
(1) medications: ACE inhib- Lisinopril, K+ sparing diuretics (Spironolactone), OCP- Yaz
(2) renal dysfunction
(3) dietary intake
What 3 categories of medications cause hypokalemia?
(1) diuretics
(2) insulin
(3) beta adrenergic agents
What are 3 findings on an EKG of hypokalemia?
(1) flat T wave
(2) ST segment depression
(3) formation of U waves
How do you tx mild hypokalemia?
Oral KCl
How do you tx severe hypokalemia?
IV KCl
How do you tx hypokalemia + low Mg+?
Mg+ first THEN K+ (b/c must be cardioprotective first before fixing K+)
What 3 medications cause hyperkalemia and what is a common complication that leads to hyperkalemia?
(1) ACE inhib- Lisinopril
(2) ARBs- Losartan
(3) Aldosterone antag- Spironolactone
kidney failure/insufficiency
What are 2 clinical manifestations of hyperkalemia?
(1) muscle weakness
(2) paresthesias
What are 3 findings on an EKG of hyperkalemia?
(1) tall or peaked T waves (2) widened/bizarre QRS (3) flat P waves
What is the first agent to have on board in tx of hyperkalemia?
IV calcium (gluconate or chloride)- cardioprotective!!
What tx helps move excess K+ into the cells?
IV hypertonic glucose + regular insulin
What 4 processes require Ca+?
(1) blood coagulation
(2) nerve excitability
(3) development of action potentials for muscle contraction
(4) osteoclast activity
What are 5 common causes of hypocalcemia?
(1) parathyroid disease (2) thyroid disease
(3) thyroid or parathyroid-ectomy
(4) chronic renal failure (5) Vit D deficiency
A deficiency of what can cause pseudohypocalcemia?
Albumin
What are 2 classic physical findings of hypocalcemia?
(1) Chvostek sign: facial spasm following the percussion of the facial nerve
(2) Trousseau’s sign: spasm of the hand elicited by inflation of a BP cuff
What is a finding on an EKG of hypocalcemia?
Prolonged QT interval
What is the tx of asymptomatic hypocalcemia? Symptomatic?
Asymptomatic: oral Ca+ Symptomatic: IV Ca+
What are the 3 most common causes of hypercalcemia?
(1) hyperparathyroidism
(2) bone malignancy (multiple myeloma)
(3) prolonged immobilization
