 Welcome to Nursing School Explained and on this video on isotonic IV fluids. Before we get started looking into more of the details of isotonic fluids, let's review some principles that will help you understand more of what isotonic fluids are and when we use them. So some of those principles that I'd like to review are the different fluid compartments. So we have intracellular fluid as well as extracellular fluid meaning inside the cell and outside the cell, pretty self-explanatory. But when it comes to extracellular fluid we also need to distinguish between two different fluid spaces which is the intravascular fluid compartment inside the blood vessels and then the interstitial which is in between the intravascular and the intracellular fluid. And then keep in mind that things diffuse and by the principle also of osmosis move back and forth from the intravascular to the intracellular space through that interstitial space. And of course there are certain conditions that can also affect the interstitial space. And then fluid shifts whenever we think about fluid shifting we always have to think about osmosis because that's the principle of water moving across a semipermeable membrane. If you recall from a physiology class, if we have a beaker here with that semipermeable membrane in the middle the concentration on either side of the semipermeable membrane here is the same. Which means that there is no fluid shift because typically the body wants to achieve homeostasis by equalizing the two sides. But with isotonic IV fluids there is the same concentration that we have in the plasma as well as in the IV fluids that we administer. So whenever we give the IV fluids in the intravascular space there is no fluid shift because they have the same concentration. One more important thing is that the normal serum osmolarity which is the concentration of particles in the blood is between 275 and 295 mOs per liter. And this is a number that you'll just have to memorize. And then how does this apply to isotonic IV fluids? So like we said because there's no osmotic shift because the concentration is the same in the intravascular space and in the IV bag there is no fluid shift. So the isotonic fluids that we administer into that intravascular space is the same concentration as inside the cell and so there is no fluid shift which means that the isotonic fluids just stay inside that intravascular space and help us in certain conditions. So isotonic fluid stays in the intravascular space, it just stays in the blood vessels. If you need more help in reviewing these basic principles I have a couple other videos where I go in more detail to kind of go into the physiology and take it a few steps back so that you can really apply these principles to the IV fluid administration because that's really the baseline that you need to understand in order to apply IV solutions to specific patient care scenarios. So now over here there is no fluid shift, again it stays in the intravascular space and we use it when there is extracellular fluid losses. So when we lose blood anywhere in that intravascular or interstitial space which 99% of the time it's going to be intravascular. And so the solutions that we use here for our normal saline you've probably heard this term before which is 0.9% sodium and chloride. So the only electrolytes it contains is sodium and chloride. And we use it when the patient loses fluids in that extracellular fluid compartment due to vomiting, diarrhea and dehydration for example. So now they have vomited, they've lost fluids in such a way that they're intravascularly dehydrated and by replenish them with isotonic fluids we just replenish that intravascular system. The other solution that we use here is called lactated ringer solution or LR or ringers lactate like it's sometimes called. And not only does it contain sodium and chloride like normal saline but it contains sodium, chloride, potassium as well as calcium and lactate at approximately the same concentration as the serum. So these levels in the serum and again in the bag are the same so again we don't cause a fluid shift to it to stay isotonically in that intravascular space. And LR is usually used for losses due to surgery or burns when there's not just fluid loss but because we're cutting into the patient doing surgery or with burns cells get destroyed so we're losing some of those intracellular electrolytes too so now we have to replenish them. Now the patient has more needs than just sodium and chloride from just pure dehydration or vomiting, diarrhea. So they need a little bit more electrolytes replaced because of surgery or burns and that's when LR is indicated. Now we want to use lactated ringers in cautiously in patients with liver disease, hyperkalemia, alkalotic states or severe dehydration when they are really really dry because these patients in these conditions have the inability to convert lactate to bicarbonate and then most likely we're going to stick with normal saline to rehydrate them or carefully administer these electrolytes separately once we have their lab results. And for nursing considerations so any patient who is dehydrated or has intravascular fluid loss is going to have hypotension and tachycardia because those are signs and symptoms of dehydration. So we want to check the vital signs frequently to see if we are replenishing them with enough fluids so their blood pressure will increase and hopefully in turn their heart rate will decrease. Now also we want to check their lungs frequently because when we administer lots and lots of fluids into the intravascular space especially if there are patients with heart or renal disease they are at risk for fluid volume excess or fluid volume overload and in that case when the heart is weak and the kidneys are not filtering well then the fluids could back up into the patient's lungs and they could end up with crackles and fluids in the lungs which is why we want to check them frequently and then in very large quantities of normal saline administration it can lead to hypernatremia and hyperchloremia because we're giving the patient extra sodium and chloride which is actually a higher concentration than the serum usually had so if we give them extra large quantities it can just make their sodium and chloride levels that much higher. So thank you for watching this video on isotonic IV fluid administration please also watch the video I have about hypo and hypertonic IV solutions so that you know the difference and how the fluid principles apply. Thanks for watching Nursing School Explained. See you soon.