RAAS and Blood Pressure – NCLEX Review (Nursing)

00:01 Let's take a look at a very common medication group, hypertension.

00:05 What drugs do we use to treat hypertension? Well, a good way to organize them is looking at the RAAS, right? The renin-angiotensin-aldosterone system.

00:14 You end up with angiotensin II which causes very potent vasoconstriction and volume expansion.

00:25 So with vasoconstriction and volume expansion, you end up with elevated blood pressure that's why we can use medications that interact in that RAAS in multiple stages.

00:39 So let's take a look at these. I know you're familiar but I just wanna quick review.

00:43 The RAAS stands for renin so when that gets squirted out of my kidneys, it hooks up with circulating angiotensinogen.

00:53 Okay, so renin hooks up with circulating angiotensinogen and we end up with angiotensin I.

00:59 Then angiotensin I connects with ACE known as angiotensin-converting ezyme.

01:06 Then we end up with the baddest mama jama, right? Because angiotensin II is a super potent vasoconstrictor and it causes -- also stimulates the release of aldosterone which causes volume expansion.

01:25 So we got them both. More volume on board and vessels that are clamped down in my body.

01:31 In the right balance, this is brilliant that this works.

01:36 We need this but when somebody has sustained high blood pressure, chronic high blood pressure, we use medication to treat it.

01:45 Now, we can do things that interact in different sections of this process and that's what drugs that interact with the RAAS do.

01:54 Alright, so we've got this quick review of the RAAS, because we know that the blood pressure elevates due to 2 things: volume expansion and vasoconstriction.

02:04 In the volume expansion, the adrenal cortex releases aldosterone.

02:09 So we know when that happens, the body hangs on the sodium, where ever sodium goes, water follows.

02:15 Now, the vasoconstriction is due to the angiotensin II.

02:19 It is, when I say a bad mama jama, it is very bad.

02:24 It's a super potent vasoconstrictor, 4-8 times as active as norepinephrine.

02:31 So it is even stronger than anything I can hang in an IV bag for a patient in shock.

02:37 So this is the coolest part of how the RAAS works when I need it.

02:42 When it's chronically there, I'm in trouble.

02:45 Because blood pressure is impacted by my cardiac output or the SVR.

02:50 So cardiac output and SVR, preload, afterload, contractility, all those words that we talk about in cardiac care.

02:58 So if I'm gonna maintain a blood pressure, I've got these 5 players, right? The arterioles, the baroreceptors, the medulla oblongata, the hormones, and the RAAS.

03:11 All 5 of these are really important players in helping maintain a healthy blood pressure.

03:17 However, when we're out of balance, we can also use medications that impact those different areas to help us deal with hypertension.

03:25 Now, I put the normals up here just to remind you.

03:28 Normal has to be less than 120/80 now.

03:32 And I've got it also listed there, those are key numbers that you need to make sure that you're familiar with.

03:37 Now, we're talking about how we treat hypertension.

03:40 First step, diet and exercise. If that works, awesome blossom.

03:45 That's a cool deal.

03:46 But if it doesn't, and often times it doesn't because it's really hard to change diet and exercise, but if you can do, that's the best.

03:54 If not, then we're gonna look at adding another first line drug.

03:58 Usually that's considered to be thiazide diuretics or a diuretic.

04:03 Thiazide is a relatively gentler one than a loop diuretic like furosemide so after we've tried diet and exercise and it doesn't work, we may try a diuretic to see if that works.

04:15 Our target blood pressures are there and I just really wanna underscore this is where they came from so this is why it's a little different.

04:22 If you wanna have a normal blood pressure, it's gotta be less than 120 so make sure, again, I know I'm repeating myself, but because this is really important that you recognize that's our goal.