Who Benefits from Vasodilators? (Nursing)

by Prof. Lawes

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    00:01 So who benefits from vasodilator medications? That's always the question you want to ask yourself when you're studying pharmacology.

    00:08 What types of patients would I give this medication to? Well, hypertensive patients benefit even if it's chronic hypertension, they have it all the time, or they're in an extreme crisis.

    00:19 Patients with angina or chest pain.

    00:22 Patients in congestive heart failure.

    00:24 Someone who's had a myocardial infarction, which is a heart attack, or patients with peripheral vascular disease.

    00:31 Now, I know I went through that list pretty quickly.

    00:34 Don't worry. We're going to break down the drug through this and the other videos. You'll explain why vasodilators help each one of those specific diagnoses.

    00:43 Okay, so let's review what happens when your veins dilate.

    00:47 Remember, we've got vasodilators that go primarily after arterioles, that can go after both.

    00:53 And then we have those that go, particularly after the veins.

    00:56 So look at the first graphic.

    00:58 They've got a heart there, and they show you a decrease in volume.

    01:01 That means there's less blood returning to the heart, remember? Decreased preload, "pre" meaning before the heart.

    01:09 When I have less blood returning to the heart, that means when it's coming up to the right atrium and the right ventricle, there's less ventricular stretch because there's just less volume stretching out that ventricle.

    01:21 Well, where is the blood? Remember, when I give venous dilators, more of the blood stays out in my periphery, like my legs, for example. So, less blood returns to the heart. That's a decreased preload and less ventricular stretch.

    01:38 Now, I love this next picture, because look, he's got a little nightcap on, you see the Z's.

    01:43 The heart doesn't have to work as hard.

    01:45 Because there's less blood coming back to the heart, there's less ventricular force because it's not as full, the heart doesn't have to work as hard.

    01:56 Now, the heart also pumps out relatively less blood per minute, why? I have a decreased cardiac output because I have less preload and less ventricular stretch.

    02:07 Now, before we go on, I want you to stop for just a minute.

    02:11 Think back through those list of diagnoses that we talked about right before this.

    02:16 Think through that list and see how would less blood help a patient with hypertension? How would the heart not having to work as hard help a patient with congestive heart failure? How would the heart pumping out relatively less blood a minute impact a patient's blood pressure? Now, I'm not going to tell you the answers right now, I want you to see what you can synthesize and put together as we're walking through this, and we'll come back and summarize the answers later on.

    02:45 So, in a nutshell, we've got less tissue perfusion.

    02:49 Because less blood is returning to the heart, I have less cardiac output, and the heart isn't working as hard.

    02:56 Doesn't mean it's going to be detrimental, it just means there's going to be technically less tissue perfusion.

    03:02 Now, what about those arterioles, those tiny branches of the artery? What happens when they dilate? Well, there's our friend, the heart, with a nightcap on, the heart doesn't have to work as hard.

    03:14 Now, I want to make sure that concept makes sense to you.

    03:16 Remember, the arterioles, we're talking about those right outside the heart, what the heart is pumping against.

    03:21 If I dilate those arterioles, the heart doesn't have to work as hard.

    03:28 That's why we have decreased afterload after the heart.

    03:33 Also, the heart is going to pump out relatively more blood per minute.

    03:36 You know, if I'm in the gym and you load up my weights that they're super heavy, I can't get it up very high.

    03:43 But if you drop those weights off the bar, I can pump a lot faster, and I can put out more.

    03:49 Well, that's what happens to your heart. When it's not having to work as hard, it can pump out a lot more blood, which we call cardiac output.

    03:58 So you have increased cardiac output because it's not working as hard.

    04:02 All that's accomplished with an arteriole dilation.

    04:06 So therefore, we have more tissue perfusion.

    04:10 That was a lot of words.

    04:12 Before we go on to the next slide, I want you to see, why does a heart not having to work as hard lead to more tissue perfusion? Well, a heart that isn't overstressed can just produce better, it can be more efficient, and it can deliver more oxygenated blood to your tissues.

    04:29 Because that's the goal, right? The blood that's coming out of the heart has returned from the lungs, goes into that left atrium, the left ventricle, and out to the rest of the body.

    04:39 That's kind of our goal. We want oxygenated blood perfusing all of our tissues.

    04:45 Now, let's go back through that list.

    04:48 How would somebody on a vasodilator medication be treated for hypertension? Well, the benefits are clear, right? We have vasodilating of the arterioles, we're going to have a lower blood pressure. If we dilate those veins, we're also going to have a lowered blood pressure.

    05:05 Somebody with chest pain can benefit from the ways that vasodilators make afterload lower. The heart doesn't have to work as hard.

    05:13 It's not going to need as much oxygen.

    05:15 That's how a vasodilator can help with angina.

    05:18 Now with congestive heart failure, that's kind of a floppy, mushy heart, just isn't functioning super efficiently.

    05:25 Maybe the patients had an MI, it's taken a hit, heart's just over, it's gotten bigger and floppy.

    05:32 We need to decrease the workload of a heart that's experiencing congestive heart failure.

    05:37 That's how vasodilators help somebody in congestive heart failure.

    05:41 Same thing with an MI, we want to take the workload off that heart.

    05:45 Vasodilators help us do that by decreasing afterload and decreasing preload.

    05:52 Now, peripheral vascular disease is just another issue of perfusion and that's how they vasodilators are extremely helpful in that disease.

    About the Lecture

    The lecture Who Benefits from Vasodilators? (Nursing) by Prof. Lawes is from the course Cardiovascular Medications (Nursing). It contains the following chapters:

    • Who Benefits from Vasodilators?
    • What Happens When Veins Dilate?
    • What Happens When Arterioles Dilate?
    • Reflection: Who Benefits from Vasodilators?

    Included Quiz Questions

    1. Congestive heart failure
    2. Hypertension
    3. Angina
    4. Hypotension
    5. Hyponatremia
    1. Less blood returns to the heart.
    2. More tissue is perfused.
    3. The heart works harder.
    4. The heart pumps out relatively more blood per minute.
    5. More blood returns to the heart.
    1. More tissue is perfused.
    2. The heart works harder.
    3. The afterload is increased.
    4. Less tissue is perfused.
    5. The heart pumps out relatively more blood per minute

    Author of lecture Who Benefits from Vasodilators? (Nursing)

     Prof. Lawes

    Prof. Lawes

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