Facts Fluids and Electrolytes Flashcards
a pediatrics total body water is ________% of their body weight
75-80%
pediatrics are susceptible to significant changes in body fluids such as
dehydration
total body water is affected by aging by:
decreased percent of TBW
* decreased free fat mass and decreased muscle mass
* renal decline
* diminished thirst perception
at the arterial end of the capillary, hydrostatic pressure _______ oncotic pressure and fluid moves ______ the interstitial space. what is this called?
exceeds
into
filtration
at the venous end of the capillary, hydrostatic pressure ______ oncotic pressure and fluid moves ______ the interstitial space. what is this called?
is less than
out of
reabsorption
______ maintains the osmotic balance of the ECF
sodium
______ maintains the osmotic balance of the ICF
potassium
causes of edema
increase capillary hydrostatic pressure
* venous obstruction or salt and water retention
decrease plasma oncotic pressure
* albumin production is lost or diminished - albumin attracts and holds water within blood vessels
increase capillary permeability
* inflammation
lymph obstruction (lymphedema)
sodium role
primary ECF cation
regulates osmotic forces, thus water
nerve impulse conduction
cellular chemical reactions
acid-base balance
membrane transport
chloride role
primary ECF anion
provides electroneutrality
increases and decreases in chloride concentration are _______ to changes in sodium concentration
proportional
water balance is regulated by the secretion of
antidiuretic hormone (ADH), a vasopressin
produced in the posterior pituitary
sodium Na balance is regulated by
aldosterone
from adrenal cortex
what creates thirst
when there is a decrease in water or excess concentration of sodium in relation to total body water, an increase in osmolality is created which stimulates osmoreceptors, resulting in thirst
volume receptors are located in
right and left atria and thoracic vessels
baroreceptors are located in
the aorta, pulmonary arteries, and carotid sinus
isotonic fluid loss causes
dehydration and hypovolemia
signs and symptoms of isotonic fluid loss
weight loss
increased thirst
dry skin
symptoms of hypovolemia
increased heart rate
decreased urine output
decreased BP
flat neck veins
isotonic fluid excess causes
hypervolemia
causes of isotonic fluid excess
excessive IV therapy
increases in aldosterone
drugs like cortisone (prednisone)
symptoms of isotonic fluid excess
weight gain
decreased albumin
increased BP
distended neck veins
crackles heard in lungs
edema - pulmonary edema - heart failure
hypernatremia occurs when serum sodium levels are
ABOVE 145 mEq/L
hypernatremia caused by
increase in sodium
water loss
hypernatremia causes
water movement from ICF to ECF (intracellular dehydration)
causes of hypernatremia
inadequate water intake
excessive sweating
fever (increased ventilatory rate)
vomiting
diarrhea
burns
respiratory tract infections (increased ventilatory rate)
manifestations from hypernatremia
clinical: thirst, weight gain, bounding pulse, increased blood pressure
central nervous system: muscle twitching and hyperactive reflexes, confusion, coma, convulsions, cerebral hemorrhage
hyponatremia occurs when serum sodium levels are
BELOW 135 mEq/L
causes of hyponatremia
sodium loss (vomiting, diarrhea, GI suction, diuretic use)
large water intake, acute renal failure, SIADH
symptoms of hyponatremia
alters cell’s ability to depolarize and repolarize
cerebral cell swelling
changes in levels of consciousness - lethargy, confusion, seizures, coma
chloride is a major ____ of the ECF
anion
causes of hypochloremia
loss of sodium Na (hyponatremia)
elevated bicarbonate (metabolic alkalosis)
vomiting and the loss of HCl
causes of hyperchloremia
occurs with hypernatremia
bicarbonate deficit (metabolic acidosis)
potassium is a major _____ of the ICF
cation
normal range of potassium
3.5-5.0 mEq/L
potassium concentration maintained by
Na+/K+ pump
potassium involved in
cell membrane potential (especially cardiac and nerve cells)
buffering systems for acidosis and alkalosis
major route loss for K is
kidneys
distribution of K influenced by
acid-base balance
aldosterone affects potassium concentration by
increasing secretion into the urine and from sweat glands
hypokalemia occurs when serum potassium levels are
BELOW 3.5 mEq/L
causes of hypokalemia
reduced intake of potassium (more common in elderly)
increased movement of potassium into cells
increased losses of potassium
* upper GI loss: create alkalosis from stomach acid loss
* lower GI loss: diarrhea
* renal losses: diuretics
clinical manifestations of hypokalemia
muscle weakness
dysrhythmias (resting membrane potential becomes more negative - requires greater stimulus to trigger action potential, also delays repolarization)
glucose intolerance
hyperkalemia occurs when serum potassium levels are
ABOVE 5.5 mEq/L
causes of hyperkalemia
increased intake
shift of potassium from ICF to ECF
decreased renal excretion (oliguria - low urine output)
insulin deficiency (insulin facilitates movement of K into cell)
cell trauma (K can leak from cell)
clinical manifestations of hyperkalemia
mild attacks - restlessness, intestinal cramping, diarrhea
severe attacks - muscle weakness, loss of muscle tone, paralysis (resting membrane potential from -90 to -70)
dysrhythmias and cardiac arrest
