Hey everyone, it's Sarah with RegisteredNurseAriene.com and today we're going to talk about loop diuretics. And as always, when you get done watching this YouTube video, you can access the free quiz that will test you on this medication. So let's get started. As we've been going through this pharmacology series, we have been remembering the word nurse, which helps us determine those important concepts that we need to know about these drugs that we are studying.
And again, N stands for name because this tells us... how the drug works on the body. What family of drugs is it part of?
U tells us what it is used for. What does it treat? R tells us the responsibilities of the nurse. And this is where a lot of test questions will come from to determine if you know how to care for a patient who is taking this drug.
S stands for side effects and then E stands for the education pieces for the patient about this medication. So let's start with the name. We are dealing with loop diuretics. Loop tells us that this medication is going to influence how the loop of Henle works within this nephron.
And specifically, loop diuretics affect the thick ascending limb of the loop of Henle. Diuretics tells us that this medication is going to somehow increase the urinary output by affecting how sodium is reabsorbed back into the blood. And it's actually going to inhibit that process from occurring.
occurring so you have more sodium within this nephron. If you have more sodium, you're going to keep water within that nephron instead of it going back into the blood. These medications can help remove extra fluid volume from a patient who's in fluid volume overload. Now, loop diuretics are the most powerful of all the diuretics and we'll be also talking about thiazides and potassium sparing diuretics in our next videos. And to help you recognize if you're dealing with a loop diuretic or a thiazide or a potassium sparing diuretic, always look at the end of the generic name.
Loop diuretics tend to end in nide, N-I-D-E, or mide, M-I-D-E. And some examples are like bumetanide, furosemide, and torsemide, with the exception of ethylcronic acid, which doesn't end in nide or mide. So what loop diuretics do, again, is they affect...
this thick ascending limb of the loop of Henle. And particularly what it's going to do is it's going to inhibit a special protein co-transporter from doing its job. And this co-transporter is the sodium potassium chloride transporter. And what it does, just like its name says it does, is it's going to help transport some specific ions from the filtrate to go back into the interstitium into the blood.
And those ions will be... one sodium, one potassium, and two chloride. And they will take that from the filtrate and, in a sense, push it back to go back into the interstitium, which will go into the blood.
However, if we inhibit this ion transport, specifically the transport of sodium, we're going to alter some things because it's going to change the tonicity of this medulla interstitium because this area is very hypertonic. So, if we decrease its tonicity, it's going to alter how specific parts of this nephron are able to reabsorb water back into the body. Instead, more water will stay in this filtrate and, hence, will be urinated out, which hits our goal of increasing urinary output.
However, to truly understand this whole process, we've got to go back and we have to review the anatomy and physiology of this nephron. Here on the right, we have an illustration of a nephron. And if we took one and we stretched it out, it would look something similar to this and how its structures are set up.
And here on the left, we have how that nephron actually sets within the kidney. And you want to take note of this because some parts of the nephron are found in the cortex, which is like an isotonic environment compared to some of them being found in the medulla, which is a hypertonic environment. And And this helps you understand how these nephrons work with the way that they will tweak the water and the ions. So these nephrons are structures within the kidneys that allow them to function. And without them actually working properly, the kidneys won't be able to do their job.
And there are millions of these nephron units in each kidney. And they function to manage the water, ions, and waste that will be reabsorbed by the body. or excreted as urine. And the nephron can be divided into several parts.
Each part of the nephron has its own unique role for tweaking the filtrate that is created by the glomerulus until it's just what the body needs and what it doesn't need it will be excreted as urine. And these parts include the afferent arteriole and the efferent arteriole. And the afferent arteriole is going to take blood via the renal artery and deliver it to the nephron so it can be filtered. And the efferent arteriole will take that blood that's been filtered and send it back to the body. So blood enters into the nephron via the arterial and it's going to be filtered by the glomerulus.
And the glomerulus will create the filtrate which will eventually exit the body as urine. And in this filtrate are ions which are like electrolytes like potassium, sodium, magnesium, etc. water and waste. And this will drip down into Bowman's capsule.
Now it's going to encounter its first tubule where the tweaking of what will be needed by the body or excreted by the body via the the urine is going to occur. So it goes through the proximal convoluted tubule. And remember that this area so far is setting in that renal cortex, which is an isotonic environment. Then that filtrate is going to go down into the descending loop of Henle.
So this is like that first structure of the loop of Henle. And this is found in the medulla. And again, it's hypertonic.
So it's very salty compared to that iso... isotonic environment in the cortex where the salt content was equal on the inside of the nephron compared to the outside. But here in the medulla, that is different. It's really salty on the outside, which is going to play a role in the way that water is reabsorbed. So the filtrate goes down this descending limb of the loop of Henle.
And what I want you to remember about this descending limb is that it is permeable to water, but it's not permeable to ions, which means water is not permeable to ions. Water can leave this limb, but ions cannot. So because it's so salty here, hypertonic, water is going to leave this descending limb, which is going to concentrate that filtrate and make it really concentrated with sodium and all those other ions. Then the filtrate is going to go up through the ascending limb of the loop of Henle, and it's going to hit the thick ascending limb.
And And this is where loop diuretics work. Remember, they block that co-transporter, the sodium, potassium, and chloride co-transporter. And as that filtrate hits this thick ascending limb, it's really concentrated.
So normally, those ions are going to be transported, specifically that sodium, that'll help keep that renal medulla hypertonic. However, whenever we're throwing in a loop diuretic, that's not going to work very well. So then the filtrate will go up through the distal convoluted tubule.
It has left that hypertonic environment. Now it's back in the cortex where it's isotonic. Again, it's going to be tweaked depending on what the body needs. And then the filtrate is going to go down through the collecting duct and some of this area enters again into the medulla where you're going to have some more water reabsorption by the body. And then the filtrate will go through the renal pelvis and then eventually will be urinated out.
So we've just seen how filtrate is created by this nephron and how it flows through the nephron and eventually exits the body as urine. However, since we're talking about loop diuretics, we have to dive a little bit deeper into this loop of Henle and how loop diuretics affect the loop of Henle to cause diuresis to increase urinary output. And one thing it's going to do, it's going to affect how the body is going to going to reabsorb sodium.
So keep that in mind because if we're not reabsorbing sodium, it's staying in the nephron. That means water is going to stay in there and it's going to exit the body, hence increasing our urination. So we said that in the proximal convoluted tubule, the filtrate is there.
It's in that nice isotonic environment. But then once it goes down into the loop of Henle, it's going to go into the medulla, which is hypertonic. It's really salty.
And there's two parts of that loop of Henle. We had the descending limb and the ascending limb and they're really different in what they're permeable to, what they allow to leave the nephron and go back into the interstitium and into the blood. So filtrate comes down from the proximal convoluted tubule, hits this descending limb of the loop of Henle and remember that was permeable only to water, not ions.
And since it's hit this really salty environment, the water's like, hey, we're We're leaving. We like salt. The water leaves the filtrate and this lube of Henle is actually responsible for about 15 to 20 percent of water reabsorption.
So it reabsorbs a lot of water. So now water's left and the filtrate is really concentrated with these ions which is great because once it hits this ascending limb the ascending limb deals with that because remember this thick part of this ascending limb is permeable to ions those electrolytes but not water. So hits the ascending limb and you have all these little co-transporters, simboports, channels that are going to help allow ions to leave this filtrate, go through the cell, hit the interstitium, go to the blood. And they're all working together beautifully to do their job. And one of those co-transporters was the sodium potassium chloride co-transporter.
So it takes one sodium, one potassium. chloride takes it puts it back into the blood. Now the cool thing about the lube of Henle it's responsible for about 25% of the sodiums reabsorption which is going to play a role in keeping this renal medulla hypertonic keeps it salty so we can play a role with reabsorbing water because also you're collecting ducts once it hits this hypertonic environment water is going to be removed right before leaves so if we throw in something like a loop diuretic that's going to inhibit this co-transporter from transporting especially this sodium that potassium and chloride we're going to alter the tonicity of this environment which is going to decrease how much water is able to be reabsorbed through the collecting duct and from this loop of Henle so if the water is not leaving this nephron, it's staying in there because we have lots of sodium still in here.
And remember, sodium and water love each other. The water is going to stay in this nephron. It's not going to be reabsorbed through the body.
So it's going to leave the body as urine. And we've hit our goal. We have increased urinary output.
Now let's talk about what loop diuretics are used for. What do they treat? Well, we've already established with how loop diuretics affect this nephron is that they're going to increase a patient's ability to urinate. So they're going to be putting out a lot more urine.
Well, if you're putting out a lot more urine, that's dropping your fluid volume in your blood. Now, why would we want to drop a patient's fluid volume? Well, patients who are in fluid volume overload, where they have way too much fluid hanging out in the blood. And this can occur in patients who have heart failure, where the heart is just so weak, it just can't pump blood forward. And you can have different types like systolic dysfunction or diastolic dysfunction.
But the blood can backflow, go into the lungs, leading to pulmonary. edema where literally it's like the patient is drowning in their own fluid and the fluid can leak and go into the lower extremities where you have swelling there as edema. So we throw on this loop diuretic that is going to tell the blood once it's being filtered by this nephron hey we're not going to be sending too much water back to you because we're going to tell this nephron not to reabsorb this water because we're going to alter the sodium content in our nephron and around in this medulla. We're not going to make it as hypertonic. So guess what?
You're not going to have some fluid coming back to the body. Instead, this patient's going to urinate it out. Also, patients who have liver impairment where they get the side effect of ascites, where they have a lot of swelling in the abdomen that can help with that patient, the pulmonary edema as we just talked about, and hypertension.
Lipid diuretics aren't as helpful with hypertension compared to like thiazides, but sometimes they're prescribed. scribe for that to help lower the blood pressure and that would come from lowering the fluid volume which will lower the pressure. Same concept, you lower the amount of water that's going through a water hose, you're going to lower the pressure.
And it also treats hypercalcemia which is where you have a high calcium level in the blood. But how can loop diuretics treat a high calcium level in the blood? Well we've learned that loop diuretics really manipulate how ions are going to be transported back into the... blood from this filtrate because we're inhibiting this sodium potassium chloride transporter and that will throw things off so normally the filtrate will flow down through here remember once it passes this distal limb it's going to be really concentrated in ions so we're not only talking about like sodium potassium and chloride we're also talking about calcium and magnesium they're positively charged so they're going to go up in this thick ascending limb where we're having normally if we don't have a loop diuretic we will have sodium, one sodium, one potassium, and two chloride being transported over.
Also working as well doing its ion exchanges like the sodium-potassium pump, you can have potassium-chloride synborders and calcium channels. And all of this together is creating this like positive potential, this concentrated electrical gradient that can normally take this calcium and this magnesium and force it out of this filtrate. to go back into the interstitium and be reabsorbed into the blood. But if we inhibit this co-transporter, that's going to throw those things off and we'll lose that positive potential.
So the calcium and the magnesium will stay in the filtrate, will not go and be reabsorbed, and that can lower our calcium levels and our magnesium levels, more so our calcium levels. So that's why we can use this to treat high calcium levels. Now let's talk about the responsibilities of the nurse and the side effects associated with loop diuretics.
We're going to mesh the two. So with patients taking loop diuretics, they're at a huge risk for dehydration. So we want to monitor their fluid status and make sure they're not becoming dehydrated. How can we do that?
Well, we can look at their vital signs and see where's their blood pressure. Is that systolic less than 90? We've probably diurese them a little bit too much. How's their heart rate?
Are they tachycardic where it's above 100? That can be signs of dehydration along with excessive thirst, being lethargic. And we want to make sure we are strictly measuring their intake and output because we don't want the patient just consuming all this fluid and it's really undermining the effectiveness of this drug or We don't want them to be just putting out so much where they have this major negative loss of fluid compared to how much they've been taking in.
So for men, you want to make sure that you give them a urinal and you measure it every time you empty that urinal. And women, that you put the toilet hat in the toilet so you can collect the urine. And if they have the Foley, you can just look and see how much urine was put out of the Foley.
Plus, we want to make sure that they're putting out enough urine and that we're not sending them into renal failure. And we're going to be collecting their weights daily at the same time using the same scale. And we're looking and seeing how much their weight is fluctuating because weighing a patient is a great indicator of their fluid volume status and how much weight they're losing because if they're gaining three pounds in a 24-hour period, that's not good. That means they're retaining too much fluid. So we will look at that and compare that.
And we want to monitor their labs. Patients who are going to be on loop diuretics, especially those IV forms, they're going to be getting daily basic metabolic panels where we can look at their electrolytes and their renal status. So one thing you're really going to look at is the potassium.
If you can't remember anything else about loop diuretics, Remember that loop diuretics can lower the potassium level. It can cause hypokalemia. A normal potassium level is 3.5 to 5 milliequivalents per liter. And it's very common if your patient's on long-term loop diuretics or those IV routes, they're going to be receiving some type of potassium supplementation to help replace that potassium level.
And I want to point out this with digoxin. This is a big thing you need to know. We cover this in the digoxin video.
that we went over in this pharmacology series, but if your patient is on digoxin and they're taking a loop diuretic, you always, always want to look at that potassium level before you administer their next dose of digoxin because it can increase digoxin toxicity. So they're on digoxin, taking a loop, what are you going to look at? Their potassium level.
We don't want them to have hypokalemia. Now, why can they have a low potassium level? Well, what's happening is that, remember, we're not having these ions being transported across, so they're going back into the blood. So one ion that's really going to be concentrated in this filtrate will be sodium. So once the filtrate goes up, it's going to hit the distal convoluted tubule.
And in this tubule, especially the distal part, it uses a transporter that is influenced by aldosterone to reabsorb sodium. And one thing that we have learned about aldosterone in our lectures is that it will cause the body to keep sodium but excrete potassium. So we have a high amount of sodium here.
It's influenced by this aldosterone, so it's really going to enhance how the aldosterone is going to work. So you'll be keeping, reabsorbing the sodium, but you're going to be excreting potassium. Not only are you going to excrete potassium, which is going to lower the level, you're going to excrete hydrogen ions.
So the patient can also have metabolic alkalosis as well with these loop diuretics. So that is another side effect. so it can also drop your magnesium level which we talked about over here with how it's affecting how calcium magnesium are being reabsorbed and of course it can drop your sodium level because we're keeping sodium in this nephron and excreting it out.
Another thing that I want you to remember is that loop diuretics can increase uric acid levels so watch out for signs and symptoms of gout. And why is it increasing uric acid levels? Well the proximal convoluted tubule is being affected with how it's dealing with ureate and ureate is a waste and what this medication can do unfortunately is cause the body to increase its absorption absorption of urate which in turn will increase uric acid levels.
So that's another thing you have to watch out for. And another thing I want you to remember is that loop diuretics can cause inner ear damage with a condition called ototoxicity. And as a nurse, how can you prevent this from happening?
One way is slowly administering IV routes of loop diuretics. So when a patient is ordered like IV LASIKs or frosts, You want to give it slowly because we don't want to cause inner ear damage. And as a nurse, you're going to be looking at the effectiveness of this drug.
You're going to be looking at their weights. Are they losing weight, meaning they're losing fluid? You're going to see how much urine they're putting out.
Look at their I's and O's. You're going to listen to their lungs. Do they sound clear or do you hear crackles where there's still fluid in there?
And look at their edema, their swelling. Has their leg swelling went down? They're not pitting as much.
and even the patient starting to feel better. A lot of patients will report, wow, I feel so much better since I've had this fluid removed. And one thing you want to keep in mind as the nurse is when to give this loop diuretic because as I pointed out, they're very powerful and they work pretty fast.
So if the dose is ordered right before bedtime, that's probably not the best time to give it to the patient because they're going to be up throughout the night urinating, which is going to be a lot of time. going to affect their sleep and if they're trying to get to the bathroom in the dark that can increase the risk of falling. Plus let's say a dose is due but they have to go for a procedure. You want to make sure that you call that department and make sure that patient's going to have access to the bathroom because they will have to urinate after taking this medication. Now let's wrap up this lecture and let's talk about the education pieces for the patient.
So we definitely want to teach them to watch out for signs and symptoms of dehydration because they're going to be urinating a lot and we don't want to deplete their fluid volume. So you want to teach them to watch out for excessive thirst where they're not urinating at all or they're really tired and to monitor their blood pressure and heart rate at home. If they're really hypotensive where that systolic is less than 90 and all that together, they'll want to report to their physician and teaching them about following a healthy diet and eating foods that are rich in potassium because we're white.
wasting potassium. And foods that are rich in potassium are like potatoes, avocados, bananas, spinach, etc. So they definitely don't want to restrict that.
And they want to change positions slowly when they're getting up from a sitting or lying down position. Because we're changing the fluid volume status in the patient, they can have orthostatic hypotension. We don't want them to get up and fall.
So encourage that and to weigh themselves daily and to record. recorded because as a nurse that's part of one of our nursing interventions we are weighing them we want to see their fluid status so They need to do that as well and to monitor their weights and make sure that they're not gaining like no more than three pounds Per day because that could be a sign that they're retaining fluid. Okay, so that wraps up this review over loop diuretics Thank you so much for watching. Don't forget to take the free quiz and to subscribe to our channel for more videos