Fluids Flashcards
what percentage of an adults total body weight is water?
50-70 percent
what percentage of total body water is in the intracellular fluid? what percent in the ECF?
66 percent intracellular
33 percent extracellular
what two compartments are in the extracellular space? how much plasma is in each?
intravascular = 3500 mL plasma
interstitial = 10,500 mL plasma
what is the total intravascular blood volume? why is it higher than the intravascular plasma volume?
total intravascular blood volume = 5,600 mL
plasma + RBC
what is our normal total water intake daily? how much is through the following:
1) oral liquid intake
2) oral solid intake
3) metabolic
total = 2,500 mL
1) oral liquid = 1,500 mL
2) oral solid = 500-700 mL
3) metabolic: 150-400 mL/day
what is our normal water output? how much is lost through the following:
1) loss through urine
2) loss through stool
3) insensible losses (evaporation via skin and lungs)
4) loss through sweat
normal water output = 1,400-2,400 mL/day
1) through urine = 800-1500
2) through stool = 250 mL
3) insensible loss = 600-900
4) sweat = 100
for every degree above 98.6, what happens to insensible fluid losses?
2.5 ml/kg/day or fluid is lost with every degree above 98.6
what is the maximum possible urine osmolality?
1400 mOsm/L
what is the obligatory water loss (absolute minimum amount of H2O that must be excreted along with solute load daily)?
600 mL/day
if they kidneys are functioning normally, this is the minimum daily urine output
what are our daily Na losses? where do we lose most of our sodium?
daily loss = 50-150 mEq/day
most lost in urine
is excretion of sodium usually balanced with oral Na intake?
yes! we usually take in 100-150 mEq/day
what happens to serum sodium if no oral intake of Na? what about urine sodium?
serum sodium = should stay the same
urine sodium = lower sodium in urine (body will be holding onto it)
what are our normal daily K losses? how much do we normally intake?
K losses = 50-70 mEq
intake = 40-70 mEq
most of our potassium losses are through which process?
urination
what happens to serum K if no oral intake of K?
it goes down!
your kidneys are not as good as holding onto K as they are with sodium; if you get volume depleted, it potentiates the loss of potassium (so you lose more!)
what type of fluid needs will a hospitalized patient who is unable to take fluids and nutrients orally require?
basal fluids/electrolytes should be restored
what type of fluid requirements will a surgical patient require?
basal requirements PLUS losses that may have occurred via NG suction, vomiting, diarrhea, intraluminal sequestration, 3rd space losses
what might overzealous saline administration in patients with hypoalbuminemia cause?
EDEMA and NO intravascular volume expansion!
we need albumin to hold fluid in the intravascular space!
overzealous saline administration may also be detrimental in these two populations (in addition to hypoalbuminemia)
heart failure and LV dysfunction
could backup causing pulmonary edema
errors in fluid/electrolyte administration could be detrimental in these two populations
1) unrecognized renal impairment
2) unrecognized electrolyte abnormalities
keep an eye on your labs!
should a severely hypotensive burn patient receive D5W or NS for fluid resuscitation?
NS!
too much of the D5W diffuses intracellularly; doesn’t raise intravascular volume much
with normal saline, NONE goes into the intracellular space (it all remains extracellular with 1/4 going into intravascular volume!
an afebrile adult weighing 50-100 kg requires how many mL/kg water per day?
35 mL/kg/day = around 2500 mL/day
if under 50 kg, what method should you use to determine fluid requirements?
1st 10 kg: 100 mL/kg/day
2nd 10 kg: 50 mL/kg/day
weight above 20 kg: 20 mL/kg/day
sodium requirements in an adult vs. pediatric patient?
adult = 1-2 mEq/kg/day (80-120)
peds: 3-4 mEq/kg/day
potassium requirements (as KCl) in an adult vs. peds patient?
adult: 0.5-1.0 mEq/kg/day (40-70)
peds: 2-3 mEq/kg/day
