Electrolyte Disorders Flashcards
what serum sodium concentration is defined as hyponatremia?
135 mEq/L
what is the most common cause of hyponatremia in hospitalized patients?
hypotonic fluids
what can happen with mismanagement of hyponatremia?
cerebral osmotic deficiency
three parts of careful history examination for electrolyte disorders?
new medications
changes in fluid intake
fluid output
how may modest hyponatremia actually be severely symptomatic?
if it is developed acutely, over hours to days.
what are some severe symptoms of hyponatremia?
respiratory arrest
seizure
coma
brain damage
brainstem herniation
death
what is the initial step in hyponatremia treatment?
restriction of free water intake and hypotonic solution
generally, free water intake should be less than how much when doing treatment for hyponatremia?
1-1.5L a day
what type of saline may be necessary for patients with negative free water clearance?
hypertonic solution
what causes most of the serious complications of hyponatremia, like iatrogenic cerebral osmotic demyelination?
from over rapid sodium corrections. generally catastrophic and irreversible
what is sodium concentration is defined as hypernatremia?
sodium concentration greater than 145 mEq/L
what condition can usually accompany hypernatremia?
hypovolemia due to free water loss
what are the defenses against hypernatremia?
intact thirst mechanism and access to water are the primary defense
signs and sx of hypernatremia from dehydrated patient to severe
hypotension (orthostatic)
oliguria
>
lethargy, irritability, weakness
>
SEVERE: (sodium over 158 mEq/L)
hyperthermia
delirium
seizures
coma
fluids should be administered for hypernatremia over how long of a time period?
48 hr time period
what is the appropriate serum sodium concentration rate for hypernatremia?
1 mEq/L/h
what happens with severe rapid correction of hypernatremia?
cerebral edema and neurological impairment
what serum concentration of potassium is considered hypokalemia?
levels less than 3.5 mEq/L
severe hypokalemia may induce what conditions?
arrhythmias and rhabdomyolysis
what are some of the causes of hypokalemia?
insufficient dietary intake
intracellular shift from the extracellular space (insulin and beta agonists, alpha agonist stimulation)
the most common cause is GI loss from diarrhea.
why is GI loss the most common site of potassium loss?
potassium concentration in intestinal secretion is ten times higher than in gastric secretions, so more is lost with diarrhea.
Signs and SX of hypokalemia
Moderate: weakness, fatigue, cramps
Severe: flaccid paralysis, hyporeflexia, tetany, rhabdomyolysis
what might be shown on ECG with hypokalemia?
decreased amplitude and broadening of T waves, premature Ventricular contractions, Depressed ST segments
what is the fastest and easiest treatment for hypokalemia?
oral potassium supplementation (40-100mEq/day over a period of days to weeks)
