Here is the D5W. What does this mean to you?
Would you ever want to give your patient pure
water? Just like that. Would you take a syringe,
fill it up with water and here you go, my
friend. No, you are not Kevorkian, your are not turned
to euthanasia, that is
not your job on your boards and wards right
now. Your job is to keep the patient alive
please, on your clock. So you are not going
to give your patient pure water because if
you do so, where you are putting that water
straight into? Right into the cell. The cell
is going to swell and it will die. Okay.
So you don't want to do that. But there might
be situations where you might want to give
D5W and the reason that you give D5, which
is 5 percent dextrose is because it will slow
down the water's entry into the cell, meaning
to say that dextrose will get metabolized
in the ECF and water will remain obligated.
Once that dextrose gets dissolved, then the
water gets into the cell, but not like the
rush it would have been meaning like a water
fall or drinking out of fire hydrant killing
you. So this would be manageable. So let's do D5W.
It's isotonic to serum, we have glucose
dextrose rapidly metabolized leaving the pure
water. Why do you want this? So that you
don't kill the cell very quickly. It is equivalent
to giving one litre of pure water and the
statement here is telling you exactly as to
what you want to avoid. Pure water cannot
be administered because if you did then it
will enter the cell immediately causing ICF
shift and causing cell swelling and lysis.
Pure water will distribute evenly within total
body water. What does that mean to you? Tell
me the fractions really quick.
2/3, 1/3, where we
are paying attention to the 1/3 are
referring to the ECF equilibrate between those
two compartments. For example, let us say,
we have 1 liter of D5W. Now once again put
on your thinking cap. We don’t use math,
we don't use math on a consistent basis.
But when we do use it at that point you do
want to be alert. Just to make sure you cross
your T's and dot your I's. We have 1 litre
pure water that you are giving. We are going
to equilibrate between ECF and ICF, what are
you going to pay attention to? The ECF. So
here we have 333 of ECF. Of this, how much
is then going to enter your plasma? 83, 1/4,
bottom line okay. Big difference between D5W
and normal saline. Normal saline, 1 liter well
that distributes between your plasma and your
interstitium 3/4, 1/4. And
if you gave 1,000, how much of it ended up
in the intravascular space? What is 1/4
of your 1,000? If it was normal saline. One litre.
Yeah 250. Here you got them easily 83. This
is as difficult as to some of this math will
get for you, necessary though, so that you understand
your IV fluids. What is normal saline? Crystalloid
or is it a colloid? Good.
So you have your NaCl which is your crystalloid.