Hello everybody and welcome to the Nrsng YouTube channel. Today we’re going to talk about beta blockers. We’re going to talk about what beta blockers are, why they’re given and some of the side effects and nursing considerations when giving beta blockers. OK?
So if you want to download this presentation and view a special handout about beta blockers, you can go to Nrsng.com/beta. What we will have on there is we will have some of the handouts from this presentation, specifically discussing what are beta blockers, why they’re given and you can have that. It will be a PDF file that you can download for free. So go ahead and go to Nrsng.com/beta and you will be able to get that.
OK. When talking about beta blockers, first and foremost what we need to talk about is we need to talk about the sympathetic nervous system. OK? So we need to understand what exactly is being blocked, right?
All right. So with beta blockers, there we go. So with our sympathetic nervous system, what we have here is we have several different actual receptor sites. So with our sympathetic, there we go. Sympathetic nervous system or the SNS, what we’re basically talking about is our fight or flight system.
So the sympathetic nervous system is the fight or flight response and what we have is we have several different receptor sites in various locations throughout the body that respond to adrenaline or noradrenaline and when they are stimulated by adrenaline and noradrenaline, they have this fight or flight response.
OK. So that is our sympathetic nervous system, SNS or fight or flight system. So what we have here is we have alpha receptors. We have a couple of those, alpha one, alpha two. We also have beta receptors, beta one, two and three. We’re not going to really talk about three at all and then we also have dopaminergic receptors.
So what happens is when there’s a stimulus, you know, a lion jumping out at you, a test coming up, cute girl, cute boy, whatever, what will happen is you will – this SNS will be stimulated and you will have that fight or flight response.
That’s going to stimulate alpha one, alpha two, beta one, beta two receptors. OK? So that’s what’s going to happen there.
So specifically we need to talk about what are beta receptors. OK? So beta receptors, so we have beta receptors, right? OK. So we have beta one and we have beta two. OK? So our beta one receptors are found primarily in our heart.
So we have these beta one receptors and what they do is they’re basically in charge of heart rate, contractility and conduction of the heart. They’re going to act on the SA node and the AV node and they’re going to affect heart rate, conduction, and contraction in the heart. So that’s our beta one.
The beta two receptors on the other hand are found primarily in the lungs. What they’re going to deal with is they’re going to deal with like bronchodilation.
So when the beta one receptors are stimulated, you’re going to see an increased heart rate, increased conduction, increased contractility. When beta two receptors are stimulated, you’re going to see bronchodilation.
So an easy way to remember this is beta one, you have one heart. Beta two, you have two lungs. So actions of the beta receptor include – now this is specific to the heart. Actions of the beta one receptors within the heart, they’re going to increase cardiac output. They’re going to do that a couple of ways. They’re going to do that by increasing the heart rate in the SA node and that is referred to as the chronotropic effect. So chronotropic, chronological, think time. It’s going to increase heart rate.
It’s going to increase atrial contractility. So contractility is inotropic effect. With that, just remember digoxin is a positive inotrope, so it’s going to increase that contractility.
It’s also going to increase conduction, automaticity of the AV node. It’s going to increase conduction and automaticity of the ventricles. OK. So that’s basically what beta blockers or beta receptors are.
So when we’re talking about beta blockers, usually we’re referring to beta one. That’s what we’re going to be talking about today anyway. We’re going to be talking about beta one receptor blockers.
OK. Now you remember the beta one receptors are found in the heart and we saw that they – what beta one receptors do when they’re acted upon. They increase heart rate, increase contractility, et cetera.
So what happens is when we give beta one receptor blockers, what we’re doing is we’re blocking that action. So we’re stopping the central nervous system, that fight or flight response, from being able to increase the heart rate and the contractility and everything.
OK. So that’s really what’s happening here. We’re saying to the SNS, no, you cannot stimulate those beta one receptors. So that’s really kind of what’s happening.
Now what are some beta blockers that you’re going to be giving? Some of the common beta blockers are going to be like propranolol and metoprolol.
OK. A good way to remember beta blockers are these L-O-L endings. So beta blockers are L-O-L. Generally that’s what you’re going to see with the beta one blockers. You’re going to see the propranolol, metoprolol. There are a few others like esmolol that are given and so what you just really need to remember, they’re going to end in that L-O-L.
So what these are going to do is we also have cardio-selective and non-cardio-selective. So what’s going to happen here is these are going to decrease our heart rate and they’re going to help just kind of decrease that rate. That’s kind of what we’re looking for is that negative chronotrope effect there.
So now a lot of people will ask, “Well, won’t beta blockers decrease blood pressure?” Well, beta blockers are going to have an effect on blood pressure, right? Because what we’re doing is we’re decreasing our cardiac output by decreasing our heart rate.
So as we decrease our cardiac output by decreasing the heart rate, we are going to see a small drop in blood pressure. We have less volume going through. We’re decreasing the rate. There’s going to be a resulting decrease in blood pressure but you remember that their primary effect is not on blood pressure. So while you’re going to see a minor decrease in blood pressure, that’s not their goal. Their goal is to decrease our heart rate.
So sometimes it can be given to help decrease blood pressure just a bit. But remember we have our alpha one receptors, which are found in the vessels and their job is to vasoconstrict. So what we will usually do to really decrease our blood pressure is we’re going to give an alpha receptor blocker, something like nicardipine or something like that that’s going to really directly affect the vessels. Beta blockers are not affecting these alpha one receptors. They’re working just on our beta receptors.
So beta blockers are given. They block the beta one receptors. They’re decreasing cardiac output, decreasing heart rate and that’s really going to be our goal is to get our heart rate down.
So what you’re going to want to do, you’re obviously going to be wanting to assess your patients pretty often here. There’s going to be a certain – usually there are parameters written with the medication. It will be do not give if heart rate is less than 60. For example, we don’t want to go too bradycardiac and mess up the conduction system or anything like that.
So you want to monitor your patient’s heart rate. You also want to monitor their blood pressure. A lot of times, there will be parameters written to not give for systolic under 120 or so. So you’re going to monitor these two things before and after giving the medication.
Some of the other side effects are that it can actually mask blood sugars. So what’s going to happen with type one diabetics is it can actually result in like a hypoglycemia with the diabetics, type one diabetics.
With type two diabetics, it can actually cause these metabolic abnormalities and lead to hyperglycemia with type two diabetics. This is really metoprolol specifically. OK. So let’s just …