Now, we're gonna take a look at IV solutions.
Now, sometimes these can get confusing, but again they really don't need to be.
Let's do a quick review of where the fluid is in your body.
Now, the body is either inside of the cell or outside of the cell.
40% of your total fluid is inside the cell, so we call it intracellular.
60% of the total fluid is outside of the cell, that's extracellular.
So, fluid is one of two places, inside the cell or outside the cell.
When we say outside the cell, it's another one of two places. Interstitial or intravascular.
So, when we're talking about fluid volume shifting,
that's what we're talking about, into the cell, out to the cell.
60% is where? Right, it's outside of the cell or extracellular.
Now, it's located in interstitial, that's between your cells and tissues, or intravascular
which is inside your blood vessels.
That's what maintains my blood pressure.
So, when I'm taking a patient's blood pressure, intravascular volume plays a key role in that.
So, pause for just a minute, make sure you're very clear.
Two places fluid is in the cell or out of the cell.
And when it's outside the cell, it's either interstitial, or between the cells and in the tissues,
or intravascular, inside the blood vessels.
Now, we have three major types of IV solutions.
Isotonic, if I give to a patient in an appropriate amount,
shouldn't cause fluid to shift in or out of the cell.
It should just fill up the intravascular space.
That's why it's called iso meaning equal.
Hypotonic causes fluid to shift into the cell and interstitial spaces
so all of the sudden I become more concentrated inside the cell when I hang a hypotonic solution.
Now, you might be wondering, isotonic, hypotonic, why do they get these names?
Well, we're comparing the osmolality of the IV solution to what your normal blood stream
is because that's where we're administering the IV fluid.
If it's the same as blood, it's called isotonic.
If it's lower than blood, it's called hypotonic.
Now, if it's higher or more concentrated than blood, it's going to be hypertonic.
This is a really good summary slide to help you remember when we hang an isotonic solution,
it shouldn't cause fluid volume shifting. In and out of the cell, in and out of the intravascular spaces.
Hypotonic is going to cause fluid to shift into the cells.
Hypertonic is going to cause fluid to shift out of the cells.
Okay. This is an important point before you go forward reviewing IV solutions.
So, if you're still need to review this a little bit, no problem.
Just pause the video, stop and recall and play with these a little bit
unitl you're very clear which way fluid will be moving when we hang these solutions.
Now, there's some appropriate times to use these solutions and some dangerous times.
If I'm giving an isotonic solution, you notice I don't have anything listed there.
But let's take a look at hypotonic, you know that that's gonna cause fluid to shift into the cell.
The body's gonna try to get back to homeostasis,
and now, I'm more concentrated inside the cell so fluid will shift inside the cell.
It can elevate a patient's intracranial pressure.
Because the part I'm most worried about it shifting into the cell are the ones in your brain.
That could cause edema and swelling.
So, if we hang too much of this hypotonic solution,
we can put the patient at risk for elevated intercranial pressure.
Now, there's some risk for cardiovascular collapse.
Why would that be? Well, if I hang too much hypotonic fluid,
I'm gonna have volume shift out of the intravascular space and into the cell.
Blood pressure is going to lower, so that's why we say there's a risk for cardiovascular collapse.
When wanna hang this medication or this IV,
which you need to think of it seriously as you do with medications.
You hang a hypotonic solution, the patient's blood pressure is likely to drop, be pretty severe,
but you do have a risk for cardiovascular collapse if it dropped too much.
It can also have challenges with third spacing.
Now, hypertonic, you can end up with dehydrated cells.
Remember, if I hang a hypertonic solution, fluid is gonna rush out of the cells.
Sometimes that's a good thing but too much of a good thing can lead to dehydrated cells.
Patients with severe dehydration already, like a DKA
are especially at risks for further worsening their dehydration.
Alright. So, there's some important things that you need to know about these solutions
when you're hanging them.
We've talked about osmolality. Some people say tomato, tomato.
You may say osmolality, osmolarity.
The most important thing is that you keep in mind, think of it as a concentration.
We're really talking about the number of osmoles per kilogram of water.
Usually, it's used to describe fluids inside the body or in the concentration in fluid by weight.
That's what osmolality is.
Osmolarity is the number of osmoles per liter solution.
Hey, here's the point, don't get wrapped up in this.
I've given you the definitions in case you're really interested.
The most important point is that you take away, isotonic solutions are equal to blood,
hypotonic solutions are lower than blood,
hypertonic solutions are higher or more concentrated than what you'll see in blood.
So, we've listed the solutions for you here.
See, what normal osmolality is, then we've got hypertonic and hypotonic.
This is a great summary slide so make sure that you come back and review this slide
so that you know the names of these solutions,
and you know which way they would cause fluid to shift.
See, if I have a patient who already has a low blood pressure,
which of these would I not want to give?
Right, hypotonic because hypotonic solution will cause fluid to shift into the cells,
out of the intravascular space, into the cells
meaning I'll have less volume in the intravascular space
and I'll further lower that blood pressure.
Okay. So, you see why this is an important slide.
We've got the actual numbers up there, 270 to 300, that's the similar to blood.
We've got you with the fluids are
but just make sure you know which fluids are hypo, iso, hypertonic
and that you're clear when you hang one,
which way is fluid gonna shift and what impact will that have on your patient.