Systemic Vascular Resistance (Nursing)

00:01 Our next hemodynamic concept and value is Systemic Vascular Resistance.

00:06 We've kind of talked about this a little bit more, let's dive in a little bit deeper.

00:10 Systemic vascular resistance normal is 800-1200 dynes.

00:15 Remember that, 800 to 1200.

00:18 Basically, it's the resistance to blood flow of coming out of that left ventricle.

00:24 What's the pressure that that left ventricle has to overcome to get the blood flow to come out.

00:30 What affects systemic vascular resistance, the diameter of our arteries, the length of our arteries, and the viscosity of our blood affect a systemic vascular resistance.

00:42 Now, like I said, the normal is 800-1200.

00:45 If you have a systemic vascular resistance more than 800, that means your arteries are more dilated.

00:52 And if you have a systemic vascular resistance closer to 1200 or greater, your more vasoconstricted.

00:58 We'll look at that with a little bit of animation here later.

01:04 Now, increased afterload.

01:06 What increases the pressure that your heart has to beat against to get that blood flow out? Hyperthermia, aortic stenosis, cardiogenic shock and certain medications.

01:17 Anything that would cause your vasculature to vasoconstrict is going to increase that systemic vascular resistance.

01:24 Hyperthermia, if you're cold, you're vasoconstricting, you're shutting all that blood to your core.

01:29 Aortic stenosis is actually that aortic valve is really tight.

01:32 And in order to pop that valve open, that left ventricle has to contract really hard to get the blood flow out.

01:38 So the SVR is really high on that.

01:40 Cardiogenic shock causes extreme vasoconstriction of your vasculature.

01:45 And there's specific medications like Levophed, vasopressin, phenylephrine and dopamine.

01:50 Well, they cause vasoconstriction as well increasing that afterload.

01:54 So we talked about what increases afterload, let's talk about what decreases afterload.

01:59 Anything that causes vasodilation of your arteries would cause a decrease in afterload.

02:05 So anaphylactic or neurogenic shock, extremely vasodilates those arteries.

02:10 Hyperthermia, when you're running a fever, you're going to vasodilate.

02:15 Sepsis causes vasodilation and specific medications such as nitroglycerin, nitroprusside, nicardipine and cleviprex causes vasodilation of those arteries and decreasing that afterload.