 Hi, welcome to nursing school explain and this video on hypotonic IV fluid administration. Before we dive into the details of when we actually administer this fluid to patients, let's review some physiology so that you can understand what's behind the science here. And first we need to review the different fluid compartments. So we have the extracellular fluid, everything that's outside the cell, and then we have the intracellular fluid, everything that is contained within the cell. The extracellular fluid compartment also consists of two parts, which is the intra-vascular space, so anything that pertains to inside the blood vessels. And then the interstitial space, which is the space between the blood vessels and the cells and particles and water continuously move from the intra-vascular space to the intracellular and back and forth. And remember that particles move by the principle of diffusion and water or fluid moves by the principle of osmosis. So whenever we think about IV fluid administration, we can only think about osmosis because we give the patient fluids in a certain concentration and so only osmosis applies. So for these fluid shifts, we have osmosis. So if we think here, we have a beaker with the semipermeable membrane in the middle. On the left side, we have a lower concentration of particles and a higher concentration of fluids. Where on the right side, we have more particles and less water. Now by osmosis, the body always wants to achieve homeostasis. So through osmosis, the body is going to want to shift fluids from the higher concentration to the lower concentration. So fluid or water shifts. And keep in mind that osmosis, osmosis H2O shifts. So only applies to the fluids. And then the other thing that we have to know here is that the normal serum osmolarity, which is the concentration of particles dissolved in our serum, in our blood, is between 275 and 295 milliozmos per liter. That's a normal concentration. So now when we apply this to hypotonic IV fluids, we have the intravascular space and the intracellular space. In the intravascular space, when we give the patient hypotonic IV solutions, which means that the particles are lower and then in the cell, the particles are higher. And because, again, by osmosis, the body wants to maintain homeostasis. So the fluid will shift from the intravascular space into the intracellular space. So hypotonic fluid shifts from the intravascular to the intracellular fluid, causing the fluid to shift right here. Now if we look at this over here, here again, cause hypotonic solutions cause fluid or water shift into the cell. So when do we need this? So typically, hypotonic fluids are used when there's hyper-nitremia, so high levels of sodium, because if we give the patient hypotonic solution, it'll dilute out that sodium and then make that sodium level come down. And it is also used, this is the more common use, for maintenance fluids, because normal daily fluid losses are hypotonic and these are sensible as well as insensible fluid losses that we have from anything like perspiration, breathing, GI losses, maybe excessive sweating, and anything else that you can think of. So solutions that are hypotonic are 0.45% sodium chloride, which is also called half normal saline, because most likely you know that normal saline is 0.9% sodium chloride, so that's 0.45 is half of that. Then there's also a solution with 0.33% sodium chloride, which makes this a little bit lower, and this is not called a third normal saline, this is just called 0.33% sodium chloride. But then we also have solutions that contain dextrose, and those are usually D5W, which means dextrose 5% in water, and then we have D5 with the 0.45% sodium chloride, which again is dextrose 5%, but this time not in water, but with the half normal saline right here. And the important thing to know is that D5 just stands for 50 grams of dextrose, and the nice thing is that dextrose, think about dextrose being sugar, provides calories for the patient, so it has approximately 170 kilocalories per a one liter bag. So if a one liter bag of fluid that is let's say D5 with half normal saline, provides about 170 kilocalories to the patient, which might be something that they need, or maybe they have a little bit of a higher sugar need than the normal patient, and so that's when D5 is usually used. Now this is a question that always comes up, and this is a very important point here. So any solution with D5, so dextrose 5%, in the bag when you look at it in the bag is isotonic because the D5 makes up for the water, and it actually is isotonic. But as soon as it hits the patient's vein, is administrated to the body, it becomes hypotonic. And the reason is that the D5 is just used up by the body instantly for calories and for nutrition, so it's burned off, it enters the cell and it's used. So then if the body uses this right away, what we're left with is the water, or the 0.45% of sodium chloride, which are both hypotonic solutions. So this is a nice caveat to keep in mind. Now for nursing considerations, what do we have to watch out for? Because we are shifting the fluids into the cell, and that is any cell in the body, we have to be aware of cerebral edema, because it can also shift the fluid into the brain cells, and therefore we have to watch the patient's level of consciousness, ask him the four orientation questions, check for any changes in behavior to see if cerebral edema is occurring. Now because we are also given the lower concentration of sodium chloride, we want to keep an eye on their sodium levels, specifically if we've used it for the treatment of hypernatremia. And then we also want to check them for edema because, again, we cause that fluid shift into the cells, not only to the brain, where we need to check level of consciousness, but also into any cell in the body, so it could shift into the lungs, it could settle in the periphery and then show science of fluid volume excess. So we need to check the patient for edema, lung sounds, as well as peripheral edema and check them for pitting edema in the lower extremities, or perhaps even in the upper extremities. So thank you for watching this video on hypotonic IV solutions. Please also check out the other videos I have on isotonic and hypertonic IV solutions, so that you understand the differences and similarities. I also have a couple of videos that go into more of the basic application of this, so if you're interested, please go back and review those so that you understand the physiology behind IV fluid administration. Thanks for watching Nursing School Explained. 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