PA Catheter Waveforms (Nursing)

00:01 We've looked at the numbers that come from our pulmonary artery catheter.

00:04 But now let's look at our waveforms.

00:06 Depending on where the tip of that catheter is, we're going to be getting different waveforms in the right atrium, the right ventricle, the pulmonary artery, and the pulmonary artery wedge pressure.

00:17 Let's take a look at each of these individually.

00:20 And our central venous pressure, we see that we have two bumps in the waveform.

00:25 The first bump is our atrial contraction, that's when the right atrium is contracting, you see that rise.

00:31 And then we have a little dicrotic notch, which is that tricuspid valve slapping shut, creating a little ripple in the pressure.

00:38 And then we have a ventricular contraction, which is our second bump, right? Now the question I ask is, is it the right ventricle? Or is it the left ventricle that creates that bump? Well, it's not the right ventricle, because in systole, the tricuspid valve is closed.

00:54 So that right ventricle is ascending blood up into the pulmonary artery, not back up into the right atrium, so it doesn't see the right ventricle.

01:01 It actually sees the left ventricle contracting going through the body back to the right side.

01:06 So that second bump is created from the left ventricle.

01:11 The right ventricle waveform looks a lot like the arterial line waveform, except that it doesn't have a dicrotic notch.

01:17 The systolic sits between 20 and 30 mmHg, but the diastolic is around 0-5 mmHg.

01:24 Why is the diastolic so low? Well, if you think about it, it's recording the right atrium ejecting blood into the right ventricle.

01:32 And we know that the right atria is the weakest part of the heart.

01:35 So really, the right ventricle is just filled passively with blood.

01:38 So it's recording that passive blood flow.

01:42 And our pulmonary artery waveform, we see a rapid rise when the RV contracts.

01:48 Then when the RV starts to rest, we see a dicrotic notch, which is the pulmonic valve closing, and then we get this long decline.

01:56 So it's a rapid rise followed by a long decline, and then you do have a dicrotic notch in the middle of it.

02:03 Important to note that the PA diastolic is a lot higher than the RV diastolic.

02:10 They have the same systolic because they're both recording the RV contracting, but the diastolic is significantly different.

02:18 The pulmonary artery wedge pressure has three bumps in it.

02:21 It looks a lot like the CVP waveform.

02:24 It has the A wave, the C Wave and the V wave.

02:27 We're going to look more at the A wave, which is what we need to get the actual wedge pressure.

02:34 The wedge pressure is basically the mean of the A waves.

02:38 Now that we've talked about talked about a pulmonary artery wedge pressure waveform and what it looks like.

02:43 Let's talk about how do we obtain the wedge pressure.

02:48 The syringe that comes with the pulmonary artery catheter is a 3 cc syringe, but it has bubbles at 1.5 cc's to prevent the syringe from going any further back and injecting more than 1.5 cc's of air.

03:01 If you inject more than 1.5 cc's of air into the pulmonary artery balloon, it could rupture it, causing an air embolus into the lungs or you could cause a pulmonary artery rupture.

03:15 In order to get a wedge pressure, slowly inflate the syringe until a wedge waveform is achieved.

03:23 Once that's achieved, do not exceed 30 seconds with the balloon being inflated.

03:29 Now when you inflate the balloon and you don't achieve a wedge waveform, you need to contact the physician so they can advance the catheter until a wedge waveform is achieved.

03:41 When you advance the catheter the balloon needs to be inflated.

03:44 But more importantly, if we're withdrawing the catheter at all the balloon has to be deflated.

03:50 What's the reason for that? Well, you could go across the valve with a balloon that's inflated, you might rupture one of the leaflets of the valves.

03:58 So it's very important that if that physician is withdrawing the catheter that the balloon must be deflated.

04:07 It's important to know that the pulmonary artery wedge pressure has to be evaluated with an ECG in order to find the A wave.

04:15 The A wave follows the P wave of the ECG.

04:20 Now, why is the A wave and the P wave of the ECG not lined up with one another since both are atrial contraction? Well, it's important to remember that the ECG is recording electricity, which moves a lot quicker than fluid which is what's being recorded by the wedge pressure.

04:40 In order to find the A waves and the meaning of the A waves, you need to get a full screen of wedge waveform and ECG and then freeze that so that you can look at which one is A wave and record to get a mean.

04:57 Now let's take a look at the progression of the waveforms as the PA catheter is moving through the right side of the heart.

05:04 When it gets to the right atrium, you're going to have your CVP waveform which is those two bumps.

05:10 When it crosses the tricuspid valve, then you get your bounding right ventricle waveform.

05:16 Make note that the diastolic is really low.

05:19 Once the tip of the catheter passes the pulmonic valve, that diastolic will lift up, you'll have the same systolic but now you've got a diastolic and a dicrotic notch.

05:31 Then once we've advanced the catheter even further into the pulmonary branch, and we achieve wedge.

05:37 Now it drops down into what we call a pulmonary wedge pressure.

05:41 And you see it looks a lot like a central venous pressure.