Nitroglycerin – Organic Nitrates (Nursing)

by Prof. Lawes

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      Slides 06-05 Medications for Chest Pain.pdf
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    00:01 Okay. So, let's look at nitrates.

    00:04 This is the drug that most people have seen, but I want to break it down for you, so you become an expert in when, why, and how we use it.

    00:12 Nitrates are a vasodilator.

    00:15 Now let me explain to you how potent that vasodilator is.

    00:18 When I was a baby nurse, we used to squeeze nitroglycerin paste out on these little patches, and the doctor would order it by 1/2 inch, 1 inch, 1 and a half inch.

    00:28 And I squirted it out one day and I got some on my hand.

    00:32 I didn't think it was a big deal, so I just kind of brushed it off.

    00:36 Well, actually, what I did is I wiped it into both of my hands.

    00:40 I woke up passed out on the floor of the med room with a really bad headache.

    00:45 So, this is a potent drug and the nurses never let me forget that I did that.

    00:51 So, nitroglycerin is a potent vasodilator. It clearly dropped my blood pressure. I got really dizzy and passed out on the floor.

    00:59 Got a lot of attention that I really didn't want, but keep that in mind with your patients. It can have a pretty significant effect on people.

    01:07 It acts directly on the vascular smooth muscle, primarily the veins.

    01:12 Okay, so, I don't want to brush over that point.

    01:15 Nitroglycerin is a vasodilator that works primarily on the veins.

    01:21 Okay, so when those guys vasodilate, it ends up leaving a lot of blood out here in my extremities and not necessarily returning to my heart.

    01:31 So that's why it decreases preload, and we'll hit that concept again because I want you to be very clear on that.

    01:37 Now, we use nitroglycerine in stable angina and unstable angina.

    01:42 Remember, in unstable angina, if a nitroglycerin doesn't relieve the pain, then we try the morphine.

    01:49 So the reason nitroglycerin decreases cardiac oxygen demand -- it doesn't increase the supply, right? Because it's not dilating those arteries, it's dilating the veins, I want to walk you through that and how that works, again. Remember, when you decrease the veins, more blood stays out here in the extremities, and then what ends up happening is not as much returns to the heart, so the heart doesn't have to work as hard.

    02:14 Decreased preload means decreased demand on your heart.

    02:18 Now, nitroglycerin is also used in variant angina. Remember those spasms for variant chest pain, we use nitroglycerin and calcium channel blockers.

    02:29 So, it releases or kind of prevents those spasms in coronary arteries.

    02:34 That's how nitroglycerin helps.

    02:36 It also increases the oxygen supply. It doesn't decrease demand.

    02:41 Now, wait a minute. That seems backwards of what we just talked about.

    02:44 That's because we're talking about variant angina.

    02:47 We're talking about an angina or a chest pain that's caused by a spasm.

    02:51 Now, a spasm cuts off blood supply because nitroglycerin will help those arteries prevent those spasms. That's why it increases.

    03:00 Okay, side effects of nitrates. I think I pretty much talked to you about that, but I want to make sure you hit it, particularly in patients starting nitroglycerin for the first time, they're going to end up with that same headache that I had when I woke up on the med room floor.

    03:14 They have low blood pressure.

    03:16 I definitely had that when I woke up on the med room floor.

    03:19 And they might have a reflex tachycardia.

    03:23 Well, anytime your body's blood pressure drops kind of quickly, the body responds, the sympathetic nervous system responds by making the heart pump faster and harder. That's where the reflex, tachycardia -- it's the body's response to the drop in blood pressure caused by the nitroglycerin.

    03:41 So it's a reflex, tachy, fast; cardio, heart rate. Reflex fast heart rate.

    03:46 So your patient will be like, "Whoa, I really felt my heart about to pump out of my chest." That will get better as they take the nitroglycerin.

    03:55 Now we've got organic nitrates, which that's not something you'll find at Whole Foods.

    03:59 That's just the some other options for you. They've got some really long names.

    04:03 Isosrbide mononitrate and isosorbide dinitrate.

    04:06 The action's just like nitroglycerin, I just wanted you to be exposed to some different names.

    04:11 Amyl nitrite is another one, but it's an ultrashort-acting agent and we use it to treat acute episodes of chest pain only. But either way, these are all forms of nitroglycerin.

    04:23 So let's walk back through nitroglycerin, but I want you to pause for just a minute and see if you can write down in the margin of your notes, how does nitroglycerin relieve chest pain? Is it supply? Is it demand? What happens? What's affected; preload, afterload, contractility? So take a minute, write your thoughts down before we progress, and we'll check your work and see how you did.

    04:54 Okay, good work. I honestly hope you struggled with this question.

    04:57 That's a good thing because I don't want you to get discouraged.

    05:00 In the struggle comes the learning.

    05:03 So, if you're having to work at recall concepts, that's fantastic news because that means your brain is really engaged and you're trying to learn and understand these concepts.

    05:13 So don't avoid feeling uncomfortable.

    05:16 I promise, the struggle is where the learning happens.

    05:19 Okay, so if I have chest pain, and you give me nitroglycerin, the pain is decreased because you decrease the need for oxygen.

    05:27 Now, is it because you dilate my arteries with the nitro? No.

    05:33 It's because you dilate my veins primarily with nitroglycerin.

    05:38 So, I had chest pain, you gave me nitro, my veins dilate.

    05:43 Remember when I got really dizzy and almost passed out? Because that leads to decreased venous return to the heart.

    05:50 That means when you dilate these veins, more blood stays out in my periphery.

    05:55 Less blood returns to my heart.

    05:58 The amount of blood that returns to your heart is called preload.

    06:01 So, with less preload, I have less blood filling up my ventricles, therefore my heart is not working as hard, and that is why I don't need as much oxygen.

    06:13 Okay, how did you do? Compare your notes to our screen here.

    06:19 Make any additions or changes you need to to make sure you're really solid on this concept of how nitroglycerin actually helps with chest pain.

    About the Lecture

    The lecture Nitroglycerin – Organic Nitrates (Nursing) by Prof. Lawes is from the course Cardiovascular Medications (Nursing). It contains the following chapters:

    • Organic Nitrates: Nitroglycerin
    • Side effects of Nitroglycerin
    • Organic Nitrates: Other Options
    • Benefits of Stable Angina Treatment with Nitroglycerin

    Included Quiz Questions

    1. Vascular smooth muscle
    2. Liver tissue
    3. Bronchioles
    4. Arterioles
    1. Headache
    2. Reflex tachycardia
    3. Hypotension
    4. Hypertension
    5. Erectile dysfunction
    1. Amyl nitrite
    2. Isosorbide mononitrate
    3. Isosorbide dinitrate
    4. Nitroprusside

    Author of lecture Nitroglycerin – Organic Nitrates (Nursing)

     Prof. Lawes

    Prof. Lawes

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