Hi guys! Today we're talking about beta-blockers. Now you might be wondering
well if we're talking about beta blockers and it's an antihypertensive
why do we have a kidney on the board? You're gonna have to wait to find out
right after this.
Welcome back my name is Tammy and this is NurseMinder and on this channel we do
everything nursing so if you're new here consider subscribing below so that you
get the next video when it's released. Now if you're in healthcare maybe you've
had some patients on beta blockers and I'm wondering if you've ever asked
the question like why is this one on metoprolol and this patient's on timolol?
What's the difference? Why does it matter? Well we're going to dive into that today
but before we do we need to understand how the body
regularly works to know why we're blocking it.
So we're going to start out with a review of a little bit of anatomy and
physiology looking at the role of adrenaline and
noradrenaline which is also known as epinephrine and norepinephrine.
so what does that normally do in our body because those are the two
hormones or catecholamines that we are blocking with beta blockers.
Then once we understand what we're doing with the beta blockers, we're going to
then take a look at how to identify beta blockers, there's
different classifications, we're going to look at side effects,
patient teaching, and then of course there's a whole bunch of really cool
things to know about beta blockers that are
famously tested on NCLEX and nursing exams so be sure to stay for those
special considerations and the nclex quiz at the end. Now to
understand how beta blockers help in the fight against
high blood pressure we need to understand what they're blocking.
We're going to take a few minutes here and go over what happens naturally in
the body and why we might want to prevent that from happening.
if you've ever been scared or potentially been chased by a dog
you know that you have this fight-or-flight response happening. Your
heart rate's just a pounding in there, your muscles are going full tilt, you're
breathing really fast and that's because in the kidney - here's the connection -
in the medulla, so on top of the kidney we have this thing called the adrenal
gland it looks like little hat, well right in the center of that it's
called the medulla and inside there it releases the neurotransmitter
norepinephrine which is also called noradrenaline
and epinephrine which we know commonly as
adrenaline. Now what do epinephrine and norepinephrine do?
Well very important things to help us run away from that dog.
We need our heart to pump faster in order to circulate
oxygen. In order for our heart to pump faster we need blood to return to the
heart so that we can meet up, so the heart can
meet the demands of the body, so epinephrine will increase heart rate
increases blood pressure because norepinephrine is
is increasing vasoconstriction
So the norepinephrine is a little bit more peripherally acting and it's
causing all those vessels to get smaller with one exception
we need blood pumping to our muscles so in fact
they do not constrict those vessels they dilate those vessels otherwise we
wouldn't have the oxygen and the nutrients needed
to get away from that animal that's chasing
us.
Okay i'm back there's really no animal. Now when we look at the heart we know
that there's a recipe that we have that helps
us determine how much blood the heart's pumping out
in a minute. so that's called cardiac output
and that's equal to heart rate times by stroke volume. That's the amount of fluid
we can get into the heart with every beat.
So if i am all of a sudden got this fight-or-flight response and I've got
epinephrine surging through my body you can see that it's increasing the heart
rate and if i increase the heart rate it
definitely increases cardiac output because my math tells me it has to.
My norepinephrine is increasing vasoconstriction so that's increasing
how much fluid is coming back into the heart with each beat
so the two of these together are increasing cardiac output and cardiac
output is actually what is improving our blood pressure. In
high blood pressure we want to decrease cardiac output. We can do that by
manipulating one of these two factors or both.
We can lower the heart rate which will then decrease my cardiac output.
We can lower how much blood is being pumped out with every
contraction which will decrease cardiac output,
or we can lower both and that's what a beta blocker is doing.
Now there's two classifications of beta blockers, we're going to get into that in
this video, but let's talk about who would be
prescribed a beta blocker. Now as you might expect a patient with a
diagnosis of high blood pressure or hypertension
may be on a beta blocker. It's also used to help treat patients who
are post MI, those who have heart failure primarily because those will help to
decrease the work of the heart which is what we want;
also angina, atrial fibrillation, supraventricular tachycardia, ventricular
tachycardia. But did you also know it can be used for
essential tremors and anxiety? We're going to talk a little bit about
anxiety later in this video especially if you're going to be writing
your nclex exam that's a favorite test question.
Oh and we can't forget glaucoma as well.
So how do i identify a beta blocker? Well the key is in its
ending beta blockers end in the letters l-o-l.
So I have several here on the board atenolol,
metoprolol, some common ones here. carvedilol,
nadolol, propranolol, timolol. All of these may sound familiar to your
practice so when you see a drug ending in lol
that is a beta blocker, but it's just not that easy because
we have beta 1 blockers and beta 2 blockers.
We need to talk about that next. So in nursing we talk about beta 1 blockers
and beta 2 blockers and one of the easiest way to
remember where their site of action is is to know
that I only have one heart and I have two lungs.
Beta 1 blockers are known as selective which means they focus
on impacting heart rate and stroke volume Beta 2 are non-selective so they're
going to impact our lungs as well, meaning they're going
to cause constriction so they're going to close
up those airways instead of opening those airways.
right So if you think about that stress response, you're running
and what's happening is we have our beta 1 blockers have been activated because my
heart rate is up and our beta 2 blockers are activated
because my airways are open so i can get lots of oxygen in.
Now we want to block those effects. So if I take a beta 1 blocker I'm going
to decrease heart rate and decrease blood
flow
which is blood pressure, if I take a beta 2 blocker I'm going to
cause vasoconstriction of the airways
so you're probably wondering now okay well if they all end in lol
how do i know the difference? We've got a simple trick for you.
When your beta blocker begins with the letter a to m
we have a beta one selective so this means this is like for this is
true like like 90 of your beta blockers
a to m they generally will be selective focusing on
reducing heart rate and blocking those beta 1 receptors in the heart.
If they begin with n to z
they're a beta two non-selective blocker and they will have
more of an impact on the lungs. Now here's the exception.
Beta blockers that begin with the letter c
are both. They sit in both the beta 1 camp and the beta 2 camp so
you may have somebody who's on carvedilol and you'll have to recognize
that the c'S are working on both areas of the body.
Those beta 1 blockers when given in high doses can
affect our beta 2 receptors as well.
So now it's time to talk about the side effects of a beta blocker.
When we think about its action we know it is meant to decrease
heart rate, decrease blood pressure, decrease stroke volume.
Now if we just think about what could happen when our cardiac output drops,
when our heart rate drops, when the amount of blood that we push out of the
heart with each pump drops, you can probably already
start to anticipate some of those side effects,
things like being tired because i'm not getting as much
circulation I'm not getting as much oxygen delivered.
Having a headache because my blood pressure has all of a sudden dropped.
We may also have pooling of blood in the extremities because as those vessels
widen the fluid starts to stay a little longer,
takes longer to get it back. Now i've got some edema in my legs
in those dependent spaces if they're laying down and you have a patient who
is bedridden it's going to be on those dependent areas so not just the legs
just an fyi, but there's some important patient teaching things
with side effects from beta blockers that you're definitely going to want to
highlight with your male patients.
We end up having a risk of decreased libido.
Men rely on blood flow for an erection and so you may have to talk to them
about the potential that they will experience decreased
libido and decreased ability to have an erection.
Another really big one for teaching when you think about this blood pressure
dropping if you've ever gotten up out of bed quickly and you felt
a little dizzy we call that orthostatic hypotension and that's a huge teaching
point for patients on beta blockers.
All right now it's time for some really really important clinical considerations.
I often find that people don't consider the impact of
a rate blocker on a patient's presentation so
let's just scale back for a second recalling that
beta 1 selective blockers those that begin with A
to M with the exception of C are focusing
primarily on decreasing heart rate heart rate heart
rate. Think about this now. When you have a fever
what happens to your heart rate? It goes up.
When you have an illness what happens to your heart rate?
It goes up. When you're dehydrated what happens to your heart rate?
It goes up. Here's my question for you. Will you see an elevated heart rate on a
patient that is being blocked in heart rate? The answer is no.
So you may have a patient with a normal heart rate that is
febrile, that does have dehydration, that does have an illness, that is fearful -
we're not going to be able to rely on that indicator to help us figure out
what's going on so that is an important clinical
consideration. The second important clinical
consideration is if you have a patient who
is dependent upon their airway so we have COPD,
asthma, any restricted airway. Remember beta 2 blockers are going to
cause bronchial constriction they're going to narrow the
airways so if you have a patient with asthma and
high blood pressure you would not want to see them on
nadolol or propranolol or timolol all those ones that cause
bronchial constriction not appropriate for somebody who has
asthma or COPD. And one last special consideration are
those patients who live with diabetes and are insulin dependent.
We may also not notice hypoglycemia the signs of hypoglycemia because of the
beta blockers.
Okay so let's talk about three special considerations that are
often tested in NCLEX but that you also need to
be aware of in clinical. What if you have a patient that's pregnant and has high
blood pressure? It happens. Are there any that are safe
to be used in pregnancy? Well for all of them you'd want to check your drug guide
however i do have one that is often prescribed
and that is labatalol, if you remember "labor" labetalol is the one that's used
for pregnancy so that's my key tip there for remembering the labetolol -
pregnancy good. Glaucoma is often treated with a beta
blocker as well and we often use timolol and so here's
my clue here is that it treats the eye "Ti" It's really actually one of the only
beta blockers that I have found that has an
"i" in it so that's a little tip timolol - eye and these are drops.
So if you get a question that says your beta blocker is being delivered by eye
drops it's glaucoma! And the last one is
anxiety. I did mention before that beta blockers are being used successfully
to help decrease anxiety and if you think about what anxiety is
people's heart rate goes up they start to hyperventilate
so we've got lungs and heart are you starting to
starting to track what I'm putting down here? Atenolol
a for anxiety, metoprolol and propranolol "p" for panic. I
haven't got a clue word for metoprolol, you'll
just have to remember that one.
When it comes to getting patients to take their antihypertensives
a lot of teaching needs to happen. Recall that when people have high blood
pressure they have no symptoms and the moment we start to
treat it we know that medications have side
effects and the side effects will feel more unpleasant than the
asymptomatic high blood pressure. The problem is high blood pressure is
causing damage and putting us at risk of heart
damage and heart attack so we really need to make sure
we're staying in touch with our patient we're communicating with them
and we're letting them know that while these side effects may be unpleasant
that's a better alternative than cardiac arrest.
One of the most important teaching points is, as patients especially
with heart failure and maybe post MI
they start on this beta blocker is that they may start to notice that
they're a little bit more tired and they got a little bit more edema. You
know they're not going to be quite happy with that because they're going to want
to carry on with life but that's a short-lived side effect and
as you know a few days into it that starts to resolve and they start to feel
better. Then the doc will reassess and they'll
look to see if they need to increase the dose.
So typically there's a cycle of starting low
work with it for a couple weeks revisit see where you're at
and then increase the dose until we get to the ideal dose where
they're starting to notice that they're feeling better overall.
Time for an NCLEX question. A 36 year old female has had her blood pressure
measured on three different occasions in the clinic and the results are
145/96, 160/104, and 152/100. A review of her history
is negative except for asthma since childhood. Which
of the following drugs do you anticipate the physician will prescribe?
Okay let's take a look at these answers. So for our 36 year old female who is
coming in with these readings of high blood pressure we definitely want to
treat this and in this case the doctor is going to
prescribe a beta blocker. Now if you selected atenolol that would
be the correct answer. Now let's talk about why that's correct
versus the other three. atenolol is cardiac selective
and this patient has a history of asthma so we would not want to
create a worsening lung condition by giving a non-selective beta-2 blocker
of which propranolol, timolol, and nadalolol
are all non-selective beta-2 and or beta2 blockers. wo well
on you! Now let's do a second one. A 49 year old male musician comes to the
office for stage fright. They tell you that a friend had told
them about using propanolol to help calm the nerves
and he wants to try this medication too. This patient also reports that they've
been having more asthma attacks lately and they hope that
propranolol will help reduce these as well. The most
appropriate next step is: A) take the patient blood pressure to
ensure they are hypertensive before prescribing
B) refer the patient to a specialist for asthma first
C) prescribe propranolol to be taken once a day
before performance for best effect D) explain that propranolol is not a good
drug for him. Take a moment to make your selection.
Aall right so let's take a look at these answers for this musician. If you had
mentioned you would prefer to
take his blood pressure first to make sure they're hypertensive
you wouldn't be wrong because we definitely want to make sure that we
prescribe this for somebody who is hypertensive but that's not what he's
here for so that's probably not the best answer.
If you selected refer the patient for asthma to a specialist that's not
really addressing the problem they just come to you for
c prescribe propranolol to be taken before
before performance well it's probably not taken
randomly like that and then d explain that this would not be the best drug for
him would be the correct answer and that is because
of the history of asthma. Remember those n to z'd
are more selective in the lung and this would definitely increase the asthmatic
attacks should he take it. Thanks for watching I
hope you learned a ton because it was an awful lot of fun bringing this video to
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