Detecting pericardial effusions with echocardiography
In this video, you will learn to recognize a pericardial effusion and differentiate pericardial and pleural fluid. You will also learn to recognize the echo signs of tamponade.
In this video, from our Echocardiography Essentials course, you will learn to recognize a pericardial effusion and differentiate pericardial and pleural fluid. You will also be able to recognize the echo signs of tamponade.
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[00:00:00] Pericardium is a sac around the heart with two layers. There's always a small amount of fluid between the two layers, allowing them to move with respect to each other but if additional fluid collects, this is referred to as a pericardial effusion. The additional fluid causes the intrapericardial pressure to increase, which then opposes the pressures within the heart and it can affect its performance. The most life-threatening and dangerous of this is being cardiac tamponade, which could be fatal if it's not recognized and
[00:00:30] managed quickly enough. So, this is what a pericardial effusion looks like. It's this black layer, here, between the two layers of the pericardium. So, this may be blood, it may be fluid, it may be pus or it may be a combination. Echo can't tell the difference. And the other thing we need to be aware of... so whilst we’ve got pericardial effusion...here...we’ve got another layer outside that, which looks like fat. And we see this increasingly in our patients. Just
[00:01:00] notice the echogenicity of that, how different it looks to the pericardial fluid. So, if we find a fluid around the heart, it's worth thinking about five things. There's lots of questions that are going to head your way now, so it's good that you have the answers ready or ideally that you've put them in your echo report. And the first question is going to be—is it really pericardial and not pleural? So, this patient actually has both. There's a pericardial effusion, here and a pleural
[00:01:30] effusion, there. And the way that I can distinguish between them is to check the position of the descending aorta. So, the pericardial effusion will be anterior to the descending aorta and the pleural will typically come behind it and it can even be further behind it, here. We want to think about the size of the effusion. So, the hemodynamic effect is not directly related to size, in that a small, quickly accumulating effusion, can be worse hemodynamically,
[00:02:00] than a larger chronic one. However, once you've found the pericardial effusion chances are you're going to be rescanning this patient, either to show that the effusion is getting worse or it's getting better. So, it's useful to have some measurements to compare with, as you monitor the patient. They're also useful for giving an indication of the severity. So, for example, less than a centimeter, we'd say was a small effusion. A moderate effusion would be between 1 and 2 cm, and a large effusion more than 2 cm. So, in this view,
[00:02:30] this effusion looks moderate to me. You're going to want to think about the distribution of the effusion. Now, they typically start posteriorly and if you think about that, the patient is likely to be lying or sitting, so they will collect at the back of the heart but as the effusion gets worse, it will start creeping upwards and surround the heart, as it goes more anteriorly. It's also worth noting whether the patient has a loculated effusion, so that's where there are sort of pockets of it or whether it is all linked together, like this
[00:03:00] because that has an effect if you're going to drain the effusion. You don't want to get stuck in a pocket and you can't drain the whole amount of fluid. And this is the big question—does the patient have signs of tamponade? Or see, this is a clinical decision but transthoracic echo signs can be really helpful. So, in this subcostal view, we can see there's a large effusion. We can see that the right ventricle is small, so that's telling us that the pressure, between the pericardial layers, is such that it's stopping this right ventricle
[00:03:30] from expanding during diastole. It is also furthermore causing the free water collapse in the diastole, so this is a worrying sign. The right-sided chambers are likely to be affected before the left, with a collapse like this but it can happen on the left side as well. We can look at the mitral Dopplers. So this is using pulse wave Doppler, at the tips of the mitral valve, in the four-chamber view. What we're doing is recording the peak velocities of the E wave, in inspiration and expiration.
[00:04:00] We've reduced the sweet speed, so we can get lots of complexes in our waveform and we're going to look at the difference between these two. So, what happens is that we get a reduced velocity, on inspiration and if this is more than 25% or 30%, that suggests we've got signs of tamponade. And in this example, it's 27%, that's making us worry that we could have tamponade. You can do the same for the tricuspid valve, where the increase occurs on inspiration and the cutoff there is 40%.
[00:04:30] The IVC is very useful. So, this is a subcostal view, focusing on the IVC, so we've got a dilated IVC that isn't collapsing very well with a sniff. So, this is a worrying sign. And then the other question you're going to be asked is—can we drain it percutaneously? So, usually, the needle would probably come in around, here and you would usually want to have ideally 2 cm, here, to position the needle. You may get away with 1 cm and if that isn't the case, an alternative drainage site may
[00:05:00] be better. You can actually use contrast to check, here in the effusion itself, so it's worth keeping your echo machine around during drainage. It can be quite hard to give a firm opinion on tamponade based on echo. The Doppler variations can occur with other pathologies and some of the changes, that can be tiny changes on septal motion, are quite difficult to spot. So, as long as you've answered the five questions and you've got your images to be able to give an answer, you can always ask someone else to make that call.