Dopamine vs Dobutamine | MOA, Pharmacology, Vasopressor, Inotrope

Author: NRSNG - NCLEX® Review (NRSNG.com)

Okay everybody, this is Jon with NRSNG.com. Today, we re gonna talk about dopamin versus dobutamine. And we re gonna have a chart online that you can download to PDF and it will kind of go over everything we talked about here, just the basic differences with dopamine and dobutamine. And also, it will cover some of the vasopressors or some of the vasopressors and their effects on the systemic vascular resistance as well as cardiac output. So, you re gonna find that at NRSNG.com/dopamine. Alright. So, why are we talking about dopamine versus dobutamine? Well, the reason is, there seems to be some confusion. There was confusion in my mind as well, obviously, of what dopamine and dobutamine are and their differences.

That s probably due to the names being somewhat similar and the fact that they re given in similar situations. Okay. So, let s talk dopamine versus dobutamine. So, first of all, we need to understand that dopamine is a vasopressor, dobutamine is not a vasopressor. That s the first thing you really need to understand. Okay. Dopamine is actually a vasopressor, it is actually an alpha 1 adrenergic agonist. So, what that means is that it s going to actually act on this alpha 1 receptors in the central nervous system, and by doing that, that s actually is going to lead to an increase in systemic vascular resistance.

So, these alpha 1 receptors are all along our vessels here okay. So, we have these little alpha 1 receptors on our smooth muscles and our, you know, which includes our vessels, and what happens is, dopamine will actually go and act on these, and by acting on those, it s gonna increase vasoconstriction. So, it acts on these alpha 1 receptors, these vessels are gonna vasoconstrict, become tighter and that s gonna lead to increased systemic vascular resistance. Okay, so, it s gonna increase that vessel squeeze. Now, Dobutamine, on the other hand, is a positive inotrope. Now, you remember, let s draw a little heart here, so here s our heart, and what these inotropes do, inotrope refers to the squeeze (How do you spell squeeze? Something like that). So, inotrope refers to the squeeze of our ventricles and so what positive inotropes actually do is they cause a greater squeeze which is going to increase our cardiac output.

So, it s gonna cause this left ventricle here to squeeze a little bit harder and that s going to lead to more output here from our aorta. Okay, so, the best way to think of this is, so, dopamine vasopressor, alpha 1 agonist. Dobutamine actually works on our beta 1 receptors in our central nervous system. So, our beta 1 receptors, they are primarily found on the heart.

Dopamine vs Dobutamine | MOA, Pharmacology, Vasopressor, Inotrope

And, we talked about this a little bit earlier in another video about beta blockers and things like this. But, beta 1 receptors are essentially, they are found in the heart. Okay, so, when beta 1 receptors are stimulated, this is part of our sympathetic nervous system, so, it s part of our fight or flight. So, as these receptors are stimulated, it s going to increase our heart rate, increase cardiac output, etc, etc. So, what happens is, we get beta blockers to block all these effects, right, to block our beta receptor.

Dobutamine, on the other hand, works to increase the effects of our fight or flight response, basically. So, dobutamine is positive inotrope, works on our beta receptors and it increases our cardiac output that way, it s a positive inotrope. So, the best way for me to remember this is dobutamine has a B in it, okay, so here s dobutamine with B and I think of that as beta, okay, so it s a beta agonist. So, it s going to increase the effects of the beta receptors.

Dopamine, on the other hand, so, there s no B in it, so it s an alpha agonist and what it s going to do is, is it s going to be a vasopressor. On the other hand, these beta receptors do not lead to those vasopressive effects. Okay, so there s a quick overview for you. Let s go over to this chart that I have here and we ll talk about some of these things on this chart here. So, dopamine is a vasopressor, dobutamine is not, it s an inotrope, not a vasopressor. Dobutamine, with a B exhibits primarily beta 1 effects, to aid in increasing cardiac output. And dopamine, depending on the dose, will exhibit an alpha 1 effect leading to vasoconstriction and therefore an increased systemic vascular resistance.

They will also exhibit a beta 1 effect that lower doses. Dopamine is a great medication for septic shock because it will contribute to increased systemic vascular resistance. And, dobutamine, on the other hand, is generally given to increase cardiac output and it s used in heart failure and cardiogenic shock. Because these doses, it will lead to less myocardial oxygen demand, so that s great in heart failure and cardiogenic shock. Okay. So, again, dopamine, for example, great in septic shock, because in septic shock, remember what s happening here is we re having this massive vasodilation and so we give our dopamine to go act on these alpha receptors, and that leads to this vasoconstriction and increased systemic vascular resistance. So, this is dopamine.

Dobutamine, over here, it s got a B in it, it s our beta. So, what happens with dobutamine, it s great for like heart failure where our ventricles aren t wanting to contract, they re dilated or whatever, in cardiogenic shock as well. These cardiogenic shock are primary insult as a broken pump, so we have a decreased cardiac output, heart failure, we re also gonna have decreased cardiac output.

So, it s a great option for heart failure and cardiogenic shock because it s gonna increase this squeeze and it s gonna push more blood out here through the aorta, okay. So, that s why dopamine and dobutamine are given in different situations. Best way to remember this is, dobutamine, B , beta, beta 1 receptors are on the heart.

Dopamine, it s a vasopressor, works on the alpha 1 receptors. Okay, so, what we ll be giving away over NRSNG.com/dopamine is going to be this little chart here. What I like about it also is it takes different vasopressors and it ranks them in order in their effect in systemic vascular resistance and cardiac output. Okay, so, this is a great little chart here. Go over there, it s free to use, free to distribute to whoever you want with, and be sure to check this out on youtube and listen to other podcasts.

We appreciate you listening. Contact me, this is Jon with NRSNG.com at contact@NRSNG.com. Thank you very much. ����� � Z\^'''�-�-�-�6�6�6;;�����Ⱦ������xndZPF

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