Lung Ultrasound Explained Clearly – Video Transcript
Read on for our latest video transcript from Dr. Jacquet’s course on the lung ultrasound!
This video introduces the ten basic signs of lung ultrasound and is a sample from the MedCram Course, Lung Ultrasound Explained Clearly The full course, which includes in-depth discussions on each of the ten signs and various lung ultrasound profiles and pathology, is available for purchase here. More and more clinicians are utilizing point of care ultrasound (POCUS) for faster and more accurate diagnoses for many conditions.
Enjoy the adapted transcript from Video 4: 10 Basic Signs of Lung US:
Ten Basic Signs of Lung Ultrasound
In this video, we’re going to introduce the ten basic signs of lung ultrasound.
Now Lichtenstein breaks this down into ten basic signs, and we will look at each of these signs in detail in subsequent videos.
So the point of this video is just to introduce them, and get you to start recognizing these ten basic signs.
The Bat Sign
The first sign is called the bat sign. And I’ll be honest, I don’t know that I can appreciate it as a bat, as Lichtenstein does, but I do appreciate the importance of the bat sign.
And the importance is to accurately identify the pleural line, because if you don’t accurately identify the pleural line, you can misinterpret things in lung ultrasound. So this is going to serve as a key landmark for us.
The way I like to think of it is layers from the outside in, as we’ve previously discussed.
We have the skin layer, the subcutaneous layer, the muscular layer here, then we have the cortex of the rib with shadowing, shadowing. And the cortex of the rib here with shadowing and shadowing. We have the intercostal area between the ribs.
And then and only then, can I identify this hyperechoic line below the ribs, an intercostal area as the pleural line.
Now Lichtenstein sees this as a bat, where the curved ribs are like the wings of the bat.
It’s like the bat’s flying towards you, and then below those wings, you can call the pleural line.
Again, I don’t know if I can identify it that way, but this will serve as a core landmark for us identifying this hyperechoic pleural line, the bat sign.
The Seashore Sign
Now the second sign is the seashore sign. In the seashore sign is identifying what normal lung sliding looks like, in both 2D and M-mode.
So if we look at this 2D picture on the left, we see here that we have rib and rib shadow, rib and rib shadow, so we know this is the pleural line, as we’ve talked about before.
And for now, just appreciate that there’s movement along the pleural line.
If we take an M-mode slice, through the pleural line, and then depict it over time, that’s what gives us this seashore appearance on M-mode, on the right.
And if we notice in the picture, here, that everything above the pleural line is relatively static.
I mean, there’s a little bit of movement in the intercostal and muscular segments. But, it’s mostly straight lines, because it’s relatively static, where everything below the pleural line is relatively dynamic.
You see all of this sparkling and movement in this artifact that is created. That is the appearance of normal lung sliding, and this is said to look like a “seashore,” or a “sandy beach,” where you have, up here, the horizon, the waves coming in, you hit the seashore, and then you have this sandy beach appearance of everything below it.
The next sign is the A-line. And again, if we identify that this is the pleural line, what A-lines are is horizontal lines that are reverberation artifact of the original pleural line.
So, we see the original pleural line here, and then we’ll notice that equidistant from the skin to the original pleural line, we have a second horizontal line, and then equidistant again, we have a third horizontal line.
Again, these horizontal lines are reverberation artifact identified as an A-line.
The Quad & Sinusoid Signs
The next two signs are the quad sign and the sinusoid sign, and these are both signs of pleural effusion, so we’re going to look at them together.
Now, if we look at the image on the bottom left, we see our normal anatomy that we’re used to, with the rib and shadow, and then below the ribs, we see the parietal pleura.
Then, between the parietal and the visceral pleura, we see that there’s fluid, and this fluid takes this quadrangle type of shape.
Because we have the rib and shadow serving as the side borders, and then the parietal and the visceral pleura serving as the top and bottom border, and if we were to take an M-mode right down through the middle of this pleural effusion and watch it out over time, what we would see is the parietal pleura here.
Then, with inspiration and expiration, we’d see the visceral pleura moving in and out, which gives this sinusoid type of appearance with the fluid depicted in between the two pleural layers.
And that’s the sinusoid sign.
The Shred & Tissue-Like Signs
The next two signs we’re going to look at together are the shred sign, which is depicted here, as well as the tissue-like sign, which is depicted here. Both of these are signs of consolidation.
Now if we look at this video down here, we see that here we have the diaphragm. Below the diaphragm is liver, and above the diaphragm, we see a little bit of pleural fluid, but we see this tissue-like area, which is an area of consolidated lung.
It almost looks like liver tissue, and that’s why some call it hepatization of the lung, because here’s the liver, but the liver has black blood vessels in it, where this has white areas in it, and those white areas are air bronchograms.
So the first sign that we’re talking about is this tissue-like sign and its tissue-like appearance of consolidated lung, with white air bronchograms inside of it.
The second is the shred sign, and the shred sign is where the consolidated lung meets normal aerated lung and creates the shredded-like pleural line.
It’s not the pleural line; it’s where the interface between the consolidation of the lung and the aerated lung meet.
It doesn’t create a straight line, like the lung line or the pleural line, but this irregular shredded-like line.
So, the shred sign and the tissue-like sign are both signs of consolidation.
The eighth sign that we’re going to talk about are lung rockets.
Now lung rockets, by definition, are greater than or equal to three B-lines per interspace. And B-lines are an artifact that we’re gonna identify here.
Now see rib, rib, with shadow, and shadow (that should be familiar to you now), with the pleural line then seen just below that.
But notice how off of the pleural line, there’s coming a bright, white vertical artifact. I imagine it as a bright white (almost flashlight beam), beaming off of the pleural line off of the screen.
Notice that it comes from the pleural line. It’s vertical, it’s bright white, it moves with the pleural line, and it obliterates this A-line.
So, B-lines, when they’re present, obliterate the A-line.
And if there is greater-than or equal-to three B-lines, we call that lung rockets. And lung rockets are a sign of interstitial syndrome.
The Stratosphere Sign
The next sign is called the stratosphere sign, or some call it the barcode sign.
And this is the M-mode equivalent of lack of lung sliding.
So if we look at this 2D video clip up here, we see rib, shadowing, rib, little bit of shadowing, so know below that is this hyperechoic line that we’ve identified as the pleural line.
But notice, looking at this pleural line, that there’s no movement along it. There’s movement of the chest wall, but there’s no movement of the pleural line, back and forth in opposition to each other.
So, if we contrast that to the seashore sign we’ve seen before, we can identify that everything above the pleural line is still relatively static.
Then again, we see the movement in the intercostal and muscular layers from time to time. That’s movement of respiration.
But below it, we don’t see that sandy beach. In fact, above and below the pleural line are now mirrored. They look exactly the same, and this is what Lichtenstein refers to as the stratosphere sign, or almost like the smoke jets coming from a jet plane in the stratosphere.
Others have identified as a bar code, or straight lines all the way across.
So, the key to identifying this sign is when everything above the pleural line and below the pleural line is identical – that’s the stratosphere sign, and it equals lack of lung sliding.
The Lung Point
The last sign we’re gonna talk about is the lung point.
The lung point is the transition between a pneumothorax, or air in the pleural space, and normal lung sliding. And if we look at this video on the left, we see rib, shadow, rib, shadow, so we know this is the pleural line.
But we see movement along the pleural line on this part, and that is lung sliding.
On the other side, we see no lung sliding, so this transition point between the two is the lung point.
And if we were to place M-mode on this, we would see that above the pleural line, we have the static area, so no significant movement.
Below the pleural line, on this side, we see the sandy beach sign with lung sliding, and then that lung sliding goes away here, where we have this stratosphere sign all in the same intercostal segment.
This is pathognomonic for pneumothorax. So burn this in your memory, the lung point.
All right, let’s review real quickly, then the ten basic signs of lung ultrasound.
Number one: the bat sign, identifying the pleural line.
Number two: the seashore sign, or the M-mode equivalent of normal lung sliding.
Number three: A-lines, reverberation artifact, horizontal lines equidistant from the pleural line.
Number four: the quad sign, or fluid between the
visceral and parietal pleura, indicative of pleural effusion.
Number five: the sinusoid sign, or during inspiration and expiration, the visceral pleura coming towards or away from the parietal pleura with fluid in between, creating the sinusoid shape, also indicative of a pleural effusion.
Number six: the shred sign, or the uneven lung line below the area of consolidation, the shredded lung sign, indicative of consolidation.
Number seven: the tissue-like sign, or tissue with air bronchograms in it, inside the lung, which is indicative of consolidation as well.
Number eight: lung rockets, these vertical flashlight-like beams coming off of the pleural line, moving with the pleural line, obliterating the A-line. These are indicative of interstitial syndrome.
Number nine: the stratosphere sign, or the barcode sign, which is indicative of lack of lung sliding.
And then number ten: the lung point, which is indicative of pneumothorax, and that’s where you have lung sliding and lack of lung sliding in the same intercostal segment.