Hey there future nurses, it's Christine from Nurse in the Making. I'm here to make nursing school a bit more manageable for you. Today we're going to talk about hypovolemia versus hypervolemia.
So first let's look at hypovolemia. It's important to know that hypovolemia has a few different names. So you might see it written as dehydration, fluid volume deficit, fluid depletion, and if hypovolemia gets really bad and is left untreated, it can lead to hypovolemic shock.
which we definitely don't want. So what actually is hypovolemia? If you break apart the word, it will tell you what it is. Hypo means low and volemia means volume.
So you don't have enough fluid in the vessels. Well, this is a problem because if you don't have volume in the vessels, you're not perfusing the vital organs and we want volume to be in the vessels. So let's look at some things that can cause hypovolemia. There are many different causes, but basically it boils down to loss of fluids from anywhere. This can be from a thoracentesis, a paracentesis, hemorrhage, an NG tube, trauma, any GI losses such as vomiting and diarrhea.
Hypovolemia can be caused by any conditions that cause polyuria. So let's break apart that word. Poly means many and urea means urine.
So this is excessive urination. And conditions such as diabetes, diabetes insipidus, these conditions cause polyuria. And of course, medications such as diuretics cause polyuria because they diurese the body.
Another thing that can cause hypovolemia is third spacing. You will see third spacing in burns and ascites. So let's look at what third spacing is.
Well, third spacing is when the fluid shifts from the intravascular space, the vein, and that fluid shifts into the interstitial space. The cells. This causes a drop in circulating blood volume causing hypovolemia. Remember when I said we want volume in the vessels? We don't want it in the cells.
If it's in the cells, it can't perfuse those vital organs. Let's look at the signs and symptoms of hypovolemia. It's really important to know these signs and symptoms because they show up everywhere and it's actually pretty easy to know them if you understand the pathology of what's going on in hypovolemia. The first sign and symptom is decreased weight, and this is not a decrease in body fat. This is acute loss of water weight.
Well, because we have less volume. As for the heart, you're going to see an increased heart rate. This is because the heart is trying to pump out fluid to the body, but there's not a lot of volume.
So the heart rate is going to be weak and thready. We're going to have a decreased blood pressure. Well, because if you think about it logically, you have less volume, which means less pressure.
We're going to have a decreased CVP. CVP is central venous pressure and this is the same concept. Low volume equals low pressure. As for respiratory, we're going to see an increased respirations. You're also going to see a decrease of urine output.
We have decreased urinary output because the kidneys either don't have enough fluid to push out or the kidneys are holding on to and compensating for what fluid they do have. As for the skin, you're going to have decreased skin turgor. Whenever someone is dehydrated, they're going to have a decreased skin turgor. This is basically when you pull up the skin normally on the hand and you're going to see the skin tent, meaning it's not going to recoil back. I'm pretty hydrated, so mine coils back fast.
But when you have decreased skin turgor, you're going to see tenting. Of course, when someone's dehydrated, you're going to have dry mucous membranes and thirst. You're also going to have flat neck veins.
This is because there's no volume in the veins and so they look flat. Now let's look at some labs you'll see in hypovolemia. There's a really easy trick to remember the labs you see.
You can remember that concentrated makes the numbers go up. So you're going to see an increase in serum osmolality, an increase in urine-specific gravity, an increase in hematocrit, an increase in serum sodium, and an increased BUN. Let's look at the treatment for hypovolemia. You want to replace the fluid loss.
This can be done PO or IV. And when you're giving fluids IV, you want to monitor for fluid volume overload. You actually can put them on the other side and push them to overload. So you want to monitor for signs and symptoms of that. As for safety precautions, hypovolemia can cause orthostatic hypotension, which increases the risk for falls.
So you want to educate your patient to rise slowly when getting up. You also want to be doing daily I's and O's and daily weights. And an important thing to remember for daily weights is you want it to be on the same time, the same scale, and with the same clothes.
We just looked at hypovolemia, but let's look at hypervolemia. Hypervolemia also has a few names. You might see it as fluid volume excess and overhydration. So let's break apart this word. Hyper means high and volemia means volume.
So we have high volume in the vessels. We have too much volume in the veins. So let's look at some things that can cause hypervolemia. Heart failure.
In heart failure, the heart is failing. It's not pumping blood out efficiently and so we have a backflow causing hypervolemia. Kidney dysfunction can also cause hypervolemia. This is because the kidneys can't do their job because they're injured.
They can't excrete the excess volume and so then you have a backup of fluids. Cirrhosis can also cause hypervolemia and increased sodium intake because where sodium goes, water flows. So sodium makes us retain fluids. Now let's look at the signs and symptoms of hypervolemia.
We have increased weight. Again, same as hypo. This is not fat weight.
This is water weight. As for the signs and symptoms of the heart, you're going to see an increased heart rate. This is the same as hypovolemia, but don't get it confused.
The heart wants to push fluid forward. So in hypovolemia you had a weakened thready pulse, but in hypervolemia you're gonna have a heart rate that's bounding from all that volume. You're gonna see an increased blood pressure and this is the same concept.
Increased volume equals increased blood pressure. Again you're gonna see an increased CVP because increased volume equals increased pressure. As for the respiratory system you're gonna have wet lung sounds.
And this is commonly referred to as crackles that you'll hear with your stethoscope. This is due to the backflow of fluids from the heart. If it backs up too much, it's going to dump it into the lungs. Pulmonary edema. Signs and symptoms you'll see relating to your kidneys is polyuria.
Remember I said that that means excessive urination? This is going to be large amounts of dilute urine. This is because the kidneys are trying to get rid of all that excess fluid.
As for the skin, you're going to see a lot of edema. There's so much fluid in the vessels that it actually leaks out into those interstitial space. You're also going to see distended neck veins.
This is called JVD, jugular vein distension, because unlike hypovolemia, we have a lot of fluid in those vessels, so they're going to look puffy and distended. Now let's look at the labs for hypervolemia. Remember how I said concentrated makes the numbers go up?
Well, in hypervolemia, we have dilution. Diluted makes the numbers go down. So we're gonna see a decreased serum osmolality, a decreased urine specific gravity, decreased hematocrit, decreased serum sodium, and our decreased BUN. Now let's talk about the treatment for hypervolemia. Remember how I said sodium makes us retain fluid?
Well we want to have a low sodium diet because where sodium goes, water flows. So decreasing sodium will decrease the amount of fluid in our body. We want to do daily I's and O's and weights just like in hypovolemia. Same time, same scale, and same close.
We're going to use medications such as diuretics because diuretics diuresis the body. It's going to pee out all that excess fluid. You want to place your patient in a high to semi-fowler's position. This makes it easier for them to breathe for those who have pulmonary edema and back flow of the fluids. Rather than laying down and having that flow in the lungs, you want to have them in an upright position.
That's all for hypervolemia versus hypovolemia. If you like this video, don't forget to subscribe to my YouTube channel. Happy studying, future nurses!