Hey everyone, it's Sarah with RegisteredNurseRN.com and in this video I'm going to be covering isotonic, hypotonic, and hypertonic solutions. And what I want you to get out of this lecture is the following. I want you to know what's happening to this cell.
when these conditions are presenting, what are the different types of fluids that may be ordered to help a patient who's in these type of conditions, and I want to hit on key concepts that you need to know for lecture exams and for the NCLEX. Now after this lecture be sure to go to my website registernursern.com and take the free quiz that goes along with this lecture. It's going to test you on these solutions, it'll give you scenarios, and you'll have to pick which options are the correct and you may see some of these questions on a lecture exam. Now the link should be in the description below or a card should be popping up and you can access that.
Okay first let's familiarize ourselves with the cell and how osmosis works because this is the foundation for understanding isotonic, hypotonic, and hypertonic solutions. So let's look at a cell. Okay, our body is made up of millions of these little things and in the cell you have the inside of your cell which is made up of the organelles, you have your electrolytes, and it's referred to as the intracellular part of the cell. Then surrounding the cell is fluid and it's also made up of electrolytes and it's referred to as the as the extracellular so intracellular is the inside remember in intracellular cellular and then extra is outside very important and then you have your solvent and in the solvent you have solutes and your body loves to have everything equal it wants the same amount on the outside that's on the inside and if one of these conditions like we're going to talk about here in a second happens the body will use osmosis to correct that.
And osmosis is where you have less of a concentration trying to move to a higher concentration through a semi-permeable membrane. So that's what's happening with osmosis. And I always like to refer to sodium and water. Sodium and water love each other, especially water loves sodium. And I like to think of it like this.
I try to always think of little illustrations to help me remember things, and maybe you're like that too. I like to think of sodium as the popular kid. And water is the kid that wants to be popular and they love hanging out with the popular kid.
So what happens is that sodium sometimes likes to congregate inside the cell or maybe it'll shift and go to the outside. But wherever it goes, water wants to go. So if sodium jumps off a bridge, water will jump off a bridge. So try to remember that because that will help you remember the hypotonic and hypertonic what's happening.
happening because what will happen is that you will have all this sodium congregated inside of a cell. Now the sodium on the outside of the cell, there won't be as many. Now according to the rule of osmosis, you will have a shift in fluid from a less concentrated, which is the outside, to a higher concentrated.
So all that water will want to move in to where sodium is congregating and it can cause different conditions. First, let's go over isotonic. Isotonic.
Okay, isotonic. Iso means equal. I-S-O.
And then tonic, the second half of the word, means concentration of the solution. So there is an equal concentration of the solution on the inside of the cell and on the outside of the cell. The body's happy. They love it having it like this. Now, the type of fluids, because in the healthcare setting, we will give isotonic fluids.
So you probably want to write these down because you want to remember them. There are four of them. and they are 0.9 saline, dextrose 5% in water, which is known as D5W, and I have an asterisk by that, and I'm going to explain that here in a second. 5% dextrose and 0.225% saline, and then lactated ringers, also known as LR.
Now, why do I have an asterisk by D5W? Now, D5W, whenever you administer it, before you administer it, it's considered an isotonic solution, but after administration... the body quickly metabolizes this dextrose and after the dextrose is gone you just have the water left over so it turns into a hypotonic solution so you may be reading some literature and it will talk about it's either hypotonic or isotonic they use them interchangeably for things and that's the reason why is because your body's absorbing that dextrose and then after absorbs it you're just left over with the other fluid and that's a hypotonic fluid so keep that in mind now why Would a patient be ordered an isotonic fluid they are ordered to increase the extracellular fluid volume because what's happened is that the patient has lost this extracellular fluid either through blood loss dehydration with vomiting diarrhea or surgery again probably with the fluid loss the mean the blood loss so we give isotonic solutions to increase this they won't cause a shift it won't this cell cause it to shrink or blow up or anything like that so we just want to replace the extracellular fluid and that's how isotonic solutions allow us to do that now let's go over hypotonic solutions hypo means under or beneath so it's low and tonic again is just the concentration of the solution so the concentration of the solution is lower than it should be and I've tried to represent it in this picture of this cell.
Right here you have this cell and notice extracellularly you have not a lot of water molecules or your solute which is sodium. But on the inside of the cell you have all this water and all these solutes. Now according to osmosis remember this part the extracellular where it's less concentrated is going to want to move where it's more concentrated which is on the inside of the cell. So what's going to happen is you're going to have this shift of all this fluid that's extracellular into the cell intracellularly and what will happen is that your cell will swell up and it can lysis mean it can rupture and break apart so that is what's happening whenever you have that side effects again are cell lysis and another thing you have to watch out for whenever you have a patient in this state is that you can deplete the circulatory systems fluid you can make them hypovol because what's happening is all this fluid that's in the blood is leaving and entering into the cell so they're not going to have any more fluid left so you really have to watch that now in the hospital setting we like to give patients sometimes hypotonic fluids because they have dehydrated cells so we will give them this fluid in certain circumstances now there's three hypotonic solutions that you need to remember and remember with this because I know it gets confusing when when you're trying to remember what's isotonic, what's hypotonic, and what's hypertonic.
What helps me remember this is the number of fluids for each. Hypo, it's low. It's the less of all the three. There's only three hypotonic solutions that you really need to remember.
They are 0.45% of saline, which is half normal saline, 0.22% of saline, which is one-fourth saline, and then 0.33%, which is one-third saline. Those are generally the most popular. And again, D5W, what we said about with isotonic, it is sometimes used as a hypotonic solution because the dextrose is metabolized. Now, why are they used? They are used, again, whenever the cell becomes dehydrated because we actually want to move all that fluid into the cell because the cell's all shrinked up.
And what causes the cell to do that? Diabetic ketoacidosis, DKA, will cause it. And hyperosmolar hyperglycemia will also cause it. cause that as well. So generally if you have a patient who is in these conditions, they will be ordered one of these solutions to help hydrate that cell back.
Now there are instances where you do not want to give a hypotonic solution and this is a popular test question. They'll give you a scenario and they may say a patient comes in with increased intracranial pressure and they are ordered 0.33% normal saline. Would you give this and you wouldn't because You will not give a patient who has increased intracranial pressure hypotonic solution because it will shift the fluid into the brain tissue and cause brain swelling, which is not good. And patients who have burns, any type of burns, and trauma because these patients are already hypovolemic. And remember, this depletes your circulatory system.
You don't want to do that anymore. Now let's go over hypertonic. Okay, hypertonic. Hyper means excessive and tonic again is the concentration of the solution. So you have too much of a concentrated solution.
going on. Let's look at this picture to see what's going to happen. Now, extracellular, if you notice, you have a lot of water molecules and you have a lot of a solute.
But on the inside of the cell, you hardly have anything at all. Remember, according to osmosis, that fluid will want to shift from a lower concentration, which is the inside of the cell, to a lower inside of the cell to a higher concentration where everyone else is at. So whenever that happens you're gonna have your cells just shrink up. and that is what's happened. So side effect is your cell is gonna shrink.
Now sometimes we want to cause this to happen because the patient has some conditions that's going on. Now what are hypertonic solutions? Now to help you remember this, there are six of those, six of these hypertonics.
So remember hypertonic is increased, so you have six of those fluids. Isotonic, you just had four of them. And remember, how many did you have for hypotonic? Three, so you have six. And what they are, is 3% saline, 5% saline, 10% dextrose in water, 5% dextrose in 0.9% saline, 5% dextrose in half normal saline, and 5% dextrose in LR.
Now, let me try to go over this to help you remember the fluid types a little bit. Pay attention to these percentages because hypo, let's look at hypo, hypo is less. Notice these numbers.
These are very low percentages. of saline. They are on the low end spectrum, so you know that they're hypotonic. Now, normal, you have 0.9 saline, that's a normal, that's isotonic, and then the 5%, and then the half with the 0.22% saline, that equals isotonic, and LR is an isotonic. Then, look over here at your hypertonic.
You have these higher percentages, 3% saline, 5% saline, very, very salty, so it's very concentrated. So whenever you're trying to analyze and ask yourself, is this a hypertonic, hypotonic, isotonic fluid, make sure you're paying attention to those percentages. Now these fluids are typically given in the intensive care unit or a unit that can really monitor a patient very closely.
And it's given via a central line usually because these hypertonic solutions are very, very hard on the veins, will cause phlebitis and things like that. And the reason you have to normally give these in the ICU is because a patient's condition can change very fast if they're not monitored closely because these fluids cause very quickly fluid overload which can lead to pulmonary edema. And if you see here, because what's happening remember is that all the fluid is shifting into your vascular system because you're just shrinking that cell up. So all this is just running through your system and if you put two much and dehydrate those cells too much you're gonna have too much volume and it's going to back up the hearts not going to be able to handle it it's going to back up into the lungs you're gonna put them in fluid overload so that is why they have to be watched very carefully now why would you give a hypertonic solution now a lot of times you will have patients who cells they're very swollen and we need to pull all that stuff out of those cells into the body so the patient can excrete them out and get rid of it. Patients with cerebral edema, we like to give that because it helps decrease the swelling by removing the fluid off of the brain.
If they have that, you may give like 3% saline. A patient who has hyponatremia, low sodium in their blood, because what's happening, you have hardly any sodium in the blood, you're going to pull all that sodium from the cell into the blood. So you're going to increase their sodium so it helps balance that out.
Okay so that is the difference between isotonic, hypertonic, and hypotonic solutions. Now go to my website registernurserin.com and take the quiz to see how well you know this material. And be sure to check out my other videos on fluid and electrolytes and thank you so much for watching and please consider subscribing to this YouTube channel.