Fluid and Electrolytes Flashcards
What portion of body fluid is ICF?
2/3
(28L)
which is more stable, ICF or ECF?
ICF
what is ICF made up of?
potassium
phosphate
what portion of body fluid is ECF?
1/3 (14L)
two components of ECF
interstitial fluid
vascular fluid
what is ECF made of?
sodium
chloride
major force in body fluid movement
osmosis
major force in IV fluid therapy
osmosis
osmosis
water moves from areas of low concentration to high concentration
diffusion
solutes move from areas of high concentration to areas of low concentration
active transport
cell membranes move molecules from areas of low concentration to areas of high concentration
(against the current)
what does active transport require?
ATP
several sugars and amino acids are actively transported in the _____________
small intestine
osmolality
concentration of solute per kilogram of water
osmolarity
concentration of solute per liter of solution
(also called tonicity)
1 liter of water = ? kg
1 kg
the higher the osmolality….
the greater its pulling power for water
serum osmolality
concentration of particles in the plasma
normal serum osmolality
285 - 295 milliosmoles per liter
(mOsm/L)
what is the major solute in plasma
sodium
what increases serum osmolality?
urea (BUN)
glucose
types of pressure involved in capillary fluid movement
hydrostatic pressure
oncotic pressure
hydrostatic pressure
pushing force of fluid against the walls of the space its in
oncotic pressure
(colloid osmotic pressure)
pulling force of proteins into vascular space
cause of pulmonary edema
hydrostatic pressure increases and congests pulmonary capillaries
interstitium is congested
large amounts of fluids are forced into alveolus
6 chemical regulators of fluid balance
antidiuretic hormone
aldosterone
glucocorticoids
atrial natriuretic peptide
brain natriuretic peptide
thirst sensation
how much fluid do nephrons of kidney filter out per day?
150-180 L/day
when does fluid conservation begin? (kidneys)
if body loses 1-2% of fluid
path of ADH
hypothalamus
posterior pituitary gland
distal tubules in kidney
what does ADH (vasopressin) do?
regulates water
what is the key assessment for fluid status?
weight
how many mL/pound?
500mL/pound
what condition causes ADH to be excreted (in order to conserve water)? (3)
drop in blood pressure
drop in blood volume
rise in blood osmolality
What conditions cause ADH to be inhibited?
(in order to excrete water)
rise in BP or blood volume
then a drop in blood osmolality
what are the major functions of ADH
vasoconstriction
regulates water
where is aldosterone secreted from
adrenal gland
main actions of aldosterone
kidneys retain Na and water
excretes K
what does aldosterone do if there is a drop in BP/blood volume/Na and an increase in K?
reabsorbs Na (water follows)
then blood volume increases
what does aldosterone do if there is a rise in BP/blood volume/Na and a decrease in K?
excretes Na (water follows)
then blood volume decreases
where is cortisol released
adrenal gland
what are glucocorticoids released in response to?
stress
what do glucocorticoids do?
cause kidney retain sodium and water
when is ANP released?
when atria is stretched (caused by high blood volume)
main actions of ANP
lower BP and blood volume
4 actions of ANP
vasodilation
decreases aldosterone
decreases ADH
increases GFR (more urine production and water secretion)
when is BNP released
when ventricles are stretched
what does BNP do and 3 ways it does it?
lowers blood volume and BP
- vasodilation
- decreases aldosterone
- diuresis of water and sodium
key lab to monitor heart failure
BNP
receptors in hypothalamus detect ______ change
1 mOsm/L
how long does it take fluid to be absorbed and distributed
30-60 minutes
2 main sources of sensible water loss
kidneys (1500 mL)
intestines (100 mL)
sources of insensible water loss
skin (600 mL)
lungs (400 mL)
how to calculate fluid needs (simple)
30 mL/kg/day
how to calculate daily fluid intake (longer)
100 ml/kg for first 10 kg
50 ml/kg for next 10 kg
20 ml/kg for any additional kg
(also 4-2-1 method for hourly)
isotonic fluid volume defecit
fluid and solute is lost proportionally
(most common)
hypotonic fluid volume loss
more electrolytes lost than water
(decreased plasma osmolality)
hypertonic fluid volume defecit
more water lost than solute
(increased plasma osmolality)
5 causes of isotonic fluid loss
low fluid intake
excessive GI fluid loss
excessive renal loss
excessive skin loss (sunburn, sweating)
third space loss
third space loss
when too much fluid leaves blood vessels and goes into interstitial space
5 causes of hypertonic fluid deficit
inadequate fluid intake
prolonged/severe isotonic loss
watery diarrhea
diabetes insipidus
increased solute intake
define orthostatic hypotension
decrease of 20mmHg
decrease of 10 mmHg
kidney output per hour
30 mL
specific gravity amt
> 1.030
direct measurement of fluid status
arterial lines
pulmonary artery catheters
central venous catheter
central venous pressure (amt)
2-8 mmHg
or
2-6 cm H2O
typical serum sodium level
135-145 mEq/L
what should ratio of HCT to HgB be?
1:3
what is the first choice intervention for replacement therapy?
oral rehydration
fluids with same osmolality of normal plasma
isotonic
used to expand volume quickly
isotonic fluid
replaces ECF and electrolyte losses
isotonic fluid
types of isotonic fluid
- 0.9% NaCl (normal saline)
- ringer’s solution
- lactated ringer’s solution
- 5% dextrose in water
why is 5% dextrose not preferred for isotonic defecit?
body uses dextrose quickly then becomes just water
provides fluid replacement with no net movement
isotonic fluids
colloid fluids vs crystalloid fluids
colloid cause H2O shifts and are larger molecules
crystalloids dont
fluids that fix hypertonic deficit (low fluid, high solute)
hypotonic fluid
fluid with lower osmolality than normal plasma
hypotonic fluid
fluid used to prevent/treat cellular dehydration
hypotonic fluid
fluid that is contraindicated in acute brain injuries
why?
hypotonic fluid
no compensation mechanisms - causes cerebral edema
fluids that require frequent VS, LOC, and circulation monitoring
hypotonic fluids
types of hypotonic fluid
1/2 NS (0.45% sodium chloride solution)
1/4 NS (0.225% sodium chloride solution)
fluids that fix hypotonic defecits (high fluid, low solute)
hypertonic fluids
fluid with higher osmolality than normal plasma
hypertonic fluid
fluid that is almost always used with an infusion pump and given in limited doses
hypertonic fluid
fluids that require frequent, close monitoring
hypertonic fluid
types of hypertonic fluids
- 3% sodium chloride
- 5% sodium chloride
- D10W (10% dextrose in water)
- 50% dextrose
- D5 1/2NS, D5NS, D5LR, D5 1/4NS
a proportional gain in fluid and solute
isotonic fluid excess
excess vascular fluid volume or excess interstitial fluid volume
isotonic fluid excess
5 causes of isotonic fluid excess
heart failure
renal failure
excess intake
high corticosteroid levels
high aldosterone levels
hypervolemia and edema
isotonic fluid volume excess
water intoxication
hypotonic fluid excess
excess fluid where more fluid is gained than solute
hypotonic fluid excess
FVE where serum osmolality falls
hypotonic
7 causes of hypotonic FVE
plain water irrigations
hypotonic IV fluids
too much plain water intake
diluted formula (infants)
SIADH (syndrome of inappropriate ADH)
psychogenic polydipsia
severe/prolonged FVE with existing diseases
4 assessments of FVE
bulging fontanels
high CVP with venous engorgement (JVD)
third spacing
vital signs