Arterial Pressure Monitoring

Hey guys, in this lesson we’re going to talk about arterial pressure monitoring. So basically arterial pressure monitoring it’s a little catheter that’s inserted into an artery.  You may have heard of the term art line or a line. It’s the same thing. It’s just a catheter that’s inserted into an artery to help monitor the arterial blood pressure. It can also be used to draw blood gases or just typical labs that you need to send down. That way the patient doesn’t get stuck.  it is usually inserted by an advanced practice provider, usually a doctor or a nurse practitioner,  CRNA,  anesthesiologist. Typically nurses are not able or allowed to insert art lines, again, depending on facility, but for the most part,  it is usually placed in an arterial artery. Most common one is the radial artery. Sometimes you can do the femoral artery but the radial one is just more practical.

Again, it measures the blood pressure just like a regular blood pressure, systolic blood pressure you’re looking for 80 to 100 or 110. And then diastolic, you’re looking for 60 to 80. It’s should still be about the same it also measures a very important factor. The mean arterial pressure, if you’ve heard of the mean arterial pressure, that is the pressure needed and the minimum pressure required to perfuse organs. So this is a very, very important number because you have got to keep this greater than 65 and if it’s at least 65, then you know that the organs are being perfused. If it’s less than that, we don’t have enough blood flow, enough output, it’s not getting to the vital organs that need blood flow. An easy way to calculate the map is your diastolic blood pressure times two. And then you add your systolic and you divide it by three.

So let’s do an example really quickly. If I have a patient with a blood pressure of a100/60, I’m going to do my  diastolic times two, which is 120. And then I’m going to add my systolic. I’m going to say it again cause I don’t know if I said it right. My diastolic times two and it’s 120 and then I’m going to add my systolic of a hundred. So I get 220 I divide that by three. So my main arterial blood pressure is 73 so this is good. If I were to have a patient with a mean arterial blood pressure of 50, it means that their organs are not perfusing. I need to get this number higher because their blood is probably maybe seventies over forties just hypothetically. So ifthey’re on pressors, I need to get this number up so that again, I know that I’m perfusing vital organs.

So a little bit more about art line.  What are they, why do people have them? What’s the indication? So usually they’re done for hemodynamically unstable patients. people who are on vasopressors that need titration cause their pressures are low and you just need to stay on it. Or a surgical patients. In the EP lab, we put in art lines for patients who are going to have ablations and they go to recovery with them so they can monitor them.  Usually you don’t see art lines on the floor. It’s usually for unstable patients. So as far as an art line goes, if you have these two things, you got to make sure that they are there. They’re present. You always got to check them when you have a patient with an art line. So here’s my patient.

Yes, I know he’s got a big arm, big legs, and here’s his hand. And so here is his radial artery. So I have an art line is inserted in here, it’s like a catheter, kind of like an IV catheter and it’s inserted into the radial artery and it’s got tubing that is attached to the pole. It’s attached to a transducer connected to some cable, so I can see it on my monitor. This transducer needs to be at the phlebostatic access level. What that means is here’s the patient’s heart. And so it would be at the level of the fourth intercostal space where the right atrium would be. So if my patient’s right atrium  is right here, I need to make sure that my transducer is leveled. So if it’s not, I would need to bring it down a little bit or bring it up a little bit cause that can alter my blood pressure readings.

It has to be leveled again with the phlebostatic access level and which is approximately where the right atrium would be. It needs to be leveled in order to get accurate blood pressure readings. So if you have a patient who has an art line and they’re sitting up to the chair.  That’s great. Just make sure that that transducer is leveled to where it needs to be so that your blood pressure readings are accurate. Another thing that you have to make sure that is there is an SPO2 probe on the same hand, if they have the radial artery where the art line is, you usually either put it on the index finger or the thumb. And what that does is it just makes sure that the ulnar artery is providing the profusion that the hand needs so that it’s still getting blood supply.

And remember that an SPO2 is how you monitor the sats. So you’ll see the saturation hopefully of 98%, and you’ll see your waveform and that’s how you know that the ulnar artery and that the radial artery is not occluded and that the ulnar artery is still providing the blood flow to the hand. So you have to have an SPO2 on the hand that has an art line. So now let’s talk about the waveforms of the art line. I’m going to try to draw this to the best of my ability, so just come stick with me a little bit. So it’s usually, it corresponds with the cardiac cycle on an EKG.

So right here you have an upward stroke and this is ventricular systole. then you have your downward stroke, which is a drop in systolic pressure. This little notch right here, this little notch is very important.  that’s your dichotic notch, which is the closure of the aortic valve. And then the descending slope is the beginning of diastole. And then the very lowest part right here, which is the end-diastolic pressure preload. So again, we go up, that’s your upward stroke, which is the ventricular systole,  then your downward stroke, which is the drop in systolic pressure, the little notch, which is the dicrotic notch. And then it descends a little bit more, which is the beginning of diastole. Your lowest point is the diastolic pressure or your preload. This is how your art line should look and it should correlate with your EKG. It will come after your QRS on an EKG.

I’m sorry I’m not the best artist, but hopefully this kind of gives you an idea of what to look for. So it’s important as nurses that you always monitor the waveforms on your arterial monitor. So a couple of other things that you need to know about this is if you ever hear the terminology damped, I’m damped it basically it means that something is kind of occluding that artery or the tubing is not right or the little catheter is kinked here’s my monitor, here’s my pole and transducer.  There, it could be that have a kink, it could be fluid, it could be a clot in there.  I flush it and do a square wave test and I make sure that I’m good in order to make sure that I’m not either underdamped or over, damped if I was to be over damned, my waveforms would look something like this.

And so my blood pressure would be very, very,  high. And it could just be that there’s air in the tubing, the longer tubing it’s loose. If I am over damped, it looks something like this and there’s not a democratic notch. That’s one of the easiest ways to tell. There’s not a dichotic notch.  blood pressures are falsely lowered, whereas this one, they are falsely elevated and it could be, again, because of a clot,  a little air embolism, some type of the catheter or some type of obstruction right here or in the tubing. So if you can just flush it and figure out what’s wrong with it.  So it’s just important to know if you’re overdamped or underdamped cause you’ll know that this is not an accurate blood pressure reading. So if you see this and the monitor is telling you that the blood pressure is 60 over 40 and your map hypothetically is 30.

Don’t treat this because you would be overdamped. So fix the problem and make sure that you have a good waveform which is similar to that. Okay. So that’s imperative when it comes to monitoring art line. So a little bit of a recap,  alines, art lines, it’s usually a hemodynamically unstable patient.  Not everybody gets one. It’s usually somebody who’s on pressors or you gotta make sure you’re monitoring their blood pressure closely. You gotta make sure that it’s leveled because that way you get accurate readings. You don’t want that transducer to be too high or too low. You gotta make sure that you’re leveled. You have to monitor the way forms,  is it a good looking, I’m going to quit trying to draw for y’all. Is it a good look in waveform or is it peaked? Okay, so, or is it overdamped?

So you got to just make sure that you know, the basic idea of how the waveforms look so you know what to monitor for. So you know that the blood pressure’s accurate. So I hope that this little lesson has helped you guys at understanding art lines. So whenever you see them on a patient, look at that monitor and make sure that you know what you’re looking at so that you know that the art line is appropriate and make sure that you guys go out and be your best selves today. And as always, happy nursing.