Evaluating lung pathologies using ultrasound

Learn how to recognize the ultrasound appearance of various pulmonary diseases, including ARDS, pulmonary contusion, and interstitial lung disease.

David Mackenzie MDCM FRCPC FACEP
David Mackenzie MDCM FRCPC FACEP
9th Jul 2018 • 5m read

Lung ultrasound is not all about pneumonias. In this lesson, from our Point-of-Care Ultrasound Masterclass, you'll learn about the ultrasound signatures of some other common lung pathologies, such as pulmonary embolism, acute respiratory distress syndrome (ARDS), pulmonary contusion, and influenza.

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Video Transcript

[00:00:00] Lung ultrasound is not all about pneumonias. In this lesson, we'll learn about the ultrasound signatures of some other common lung pathologies such as pulmonary embolism, the acute respiratory distress syndrome or ARDS, pulmonary contusion, and influenza. Let's start with pulmonary embolism. We evaluate many patients for possible pulmonary embolism. Is there a role for lung ultrasound?

[00:00:30] The answer is absolutely. You're looking at the most common lung ultrasound finding in pulmonary embolus, normal lung. This is still a helpful finding though. If you have a patient with hypoxia or dyspnea and they have no lung ultrasound finding to explain their symptoms, you don't hear anything in their lungs or their history to suggest that they have asthma or obstructive lung disease, then you have to consider pulmonary embolus more strongly. You will occasionally see lung abnormalities however

[00:01:00] in a pulmonary embolus. This is an example of a subpleural consolidation. Remember that ultrasound findings can be nonspecific. We can see this little subpleural consolidation here and the patient was ultimately diagnosed with a pulmonary embolus. This subpleural consolidation corresponded to a lung infarct seen on their computed tomography scan. One way to approach looking for this is to scan areas where patients have pleuritic pain. The other role for ultrasound in

[00:01:30] the evaluation of a possible pulmonary embolus is that if your lung ultrasound is non-diagnostic, check for a deep vein thrombosis. you can also perform an echo. By using this approach to the dyspneic patient, you can reduce the need for computed tomography. In this case, although the lung ultrasound scan was negative, the suspicion clinically was high. By going to check for deep vein thrombosis, one was diagnosed in the legs and the need for CT was eliminated.

[00:02:00] What about ARDS? This is a clip obtained from a patient who had ARDS. Notice that we can see a B line profile. There are a large number of vertical artifacts extending off the pleura, down to the bottom of the image. One feature of ARDS, on lung ultrasound, is diffused B lines but that's also true with patients in pulmonary edema. So, how do we tell them apart? There are a variety of features that help us to distinguish ARDS.

[00:02:30] If we look at some of the data comparing lung ultrasound findings, there are a few important differences to know. The first is that in ARDS, there's frequently irregular pleura. It may appear thickened or irregular. ARDS is also defined by areas of spared lung on lung ultrasound. This is a very helpful way to distinguish it from pulmonary edema. And finally, it's very common to have small consolidations, subpleural consolidations that can be seen in ARDS.

[00:03:00] Let's consider this clip from a patient who is diagnosed with ARDS. This has many of the features that we would expect. We can see B lines arising off the pleura and then we have a very irregular, lumpy looking pleura that we see right here. Adjacent, there's a small subpleural consolidation with a B line that arises off the consolidation itself. This is entirely consistent with ARDS in the right clinical context. Also, note how this operator does a nice job

[00:03:30] of reducing their depth form an initial survey to perform a targeted pleural evaluation. This is great technique. Here's the same patient, and again, we can see a small consolidation just arising off the pleura. Let's take a look at one more clip. This is again from the same patient. The key thing to note here is that we have an area of relatively spared pleura right here. This is one of the tools that we can use to differentiate pulmonary

[00:04:00] edema from ARDS. This also illustrates the importance of looking at the lung in a comprehensive way. If you stopped your lung ultrasound after finding one normal or abnormal area, you might arrive at an incorrect diagnosis. What about chest trauma? You may be familiar with the use of lung ultrasound to evaluate for pneumothorax or hemothorax, but we can also identify parenchymal injury. This clip was obtained from a patient who was in a motor vehicle collision. They had

[00:04:30] blunt trauma to their chest from the steering wheel. This shows all the characteristic findings of a lung contusion. The operator is using a linear probe, selected to look for a pneumothorax. We can see the movement that indicates lung sliding but this is clearly abnormal. There are focal B lines arising off the pleura and the pleura looks thickened and irregular. In a focal lung contusion, this is what you would expect to see. If there was a more diffused trauma to the chest, you might see an image

[00:05:00] like this, in a more wide spread fashion. But this is another example of why we have to remember the clinical picture. That same clip could have been due to a pneumonia if the patient presented with fever and a cough. But it is a good illustration that we don't want to ignore B lines on a lung ultrasound that we perform after trauma. It could mean the patient has a pulmonary contusion. Here's another example of what a lung contusion looks like on ultrasound. There's a few findings to note. There's some fluid and

[00:05:30] echoic material just superficial to the lung tissue seen here, the edge of the lung looks irregular, and we can see vertical artifacts arising off the surface of the lung. The clinical history here was that the patient had fallen off a horse three hours before presenting. But think carefully, if the fall was last week, this could just as easily have been a pneumonia from a secondary infection. Next, let's discuss influenza. This is a special case of

[00:06:00] viral illness that's worth noting. In flu season, there can be a proliferation of patients with cough and fever. Who has a bacterial pneumonia? Who needs a chest x-ray? Particularly with children, it can be helpful to evaluate with lung ultrasound first. Here is a clip from a patient who had influenza. This is very characteristic of the findings you might see. We can see that there is a subpleural consolidation and some B lines arising off the pleura and the consolidation itself.

[00:06:30] While this is very typical of influenza, we know that this is a nonspecific finding and could represent something else. So, as before, we want to interpret this finding in light of the patient in front of us. If they were hypoxic and sick, think about ARDS. If they looked okay with symptoms typical for influenza, then this ultrasound signature would fit perfectly with the flu. Here's another example taken from a patient with flu. We see multiple B lines

[00:07:00] and this can be a very common finding that we would expect to see in a patient presenting with influenza. And if the other symptoms fit, it might indicate that they need no further testing and support of care. Now, we've seen the appearance of a broad range of lung pathologies. We have an expanded scope of views for lung ultrasound. Put it to work in your patients to help them.