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The Speed of Sound

The Speed of Sound

Ultrasound a Potential Tool for Detecting COVID-19

Butts, Christine MD

doi: 10.1097/01.EEM.0000669328.45777.d8
    coronavirus, COVID-19, ultrasound
    coronavirus, COVID-19, ultrasound:
    Image 1. Low-frequency image of normal, air-filled lungs. The pleural line (arrow) is seen just deep to the rib (R). Note the repeating horizontal lines, which are A lines (arrowhead). Visit http://bit.ly/SpeedofSoundVideos to see a video of this image.
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    Figure

    I think I speak for many of us in saying that dealing with the coronavirus has been unlike anything I have ever encountered. The sheer volume of sick patients, particularly in light of how little we know, has been daunting, to say the least. How do we care for our patients while protecting ourselves? For patients who are hypoxic, do we intubate them early or wait? Do we treat them like ARDS patients or something else? How can we make the right diagnosis when tests take days? Undoubtedly, what we know will look a lot different by the time this article is published.

    Many of the diagnostic tools that we typically rely on are not practical or possible due to the risk of contamination and the high volume of patients. As is the case for many diseases, the chest x-ray often lags behind the symptoms. Many physicians in places hit hard by the virus have been using ultrasound to guide patient care and document their findings.

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    Figure:
    Image 2. Low-frequency image of the lungs demonstrating thick, confluent B lines (arrowhead) deep to the ribs (R). Note the more irregular appearance of the pleura (arrow). Visit http://bit.ly/SpeedofSoundVideos to see a video of this image.

    Changes seen on ultrasound include irregularity of the pleural line, subpleural consolidation, and signs of interstitial edema, namely B lines. To identify these findings, a low-frequency transducer can be used to evaluate the lungs, although a high-frequency transducer may be best to visualize the pleura in detail. Normally, the lungs demonstrate a thin and regular pleural line. Repeating horizontal lines, known as A lines, are artifacts created by air and seen in normal lungs. (Image 1.)

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    Figure:
    Image 3. High-frequency image of a subpleural consolidation. Note the interruption to the solid pleural line (arrowhead) and an irregular hypoechoic area (arrow).

    B lines are vertical, hyperechoic artifacts emanating from the pleural line. (Image 2.) These may be the first signs of the pulmonary effects of the coronavirus, and can be scattered or confluent. Irregularity of the pleural line may also be seen. Subpleural consolidations are hypoechoic areas adjacent to the pleural line and can range in size. (Image 3.) Larger areas of consolidation may be seen as well, but pleural effusions are not commonly seen.

    What do we do with this information? Unfortunately, we don't have all the answers yet. Studies to determine if ultrasound can be used to triage patients or guide treatment are ongoing. There are, however, a number of practical uses for ultrasound in this time of the coronavirus pandemic.

    It is becoming apparent that the coronavirus affects organs other than the lungs. Cardiomyopathy secondary to the virus is a well-described presentation. Think of looking at the hearts of your patients presenting with shortness of breath or chest tightness. The majority of our patients right now are likely COVID-positive, but other disease processes do not stop: Think about heart failure, pericardial and pleural effusions, etc. Remember that ultrasound can also be used to document bilateral lung slide after intubation.

    Finally, consider handheld or smaller devices if available to you. In most cases, they are easier to wipe down or place in a protective covering like a plastic bag than larger models.

    Dr. Buttsis the director of the division of emergency ultrasound and a clinical assistant professor of emergency medicine at Louisiana State University at New Orleans. Follow her on Twitter@EMNSpeedofSound, and read her past columns athttp://bit.ly/EMN-SpeedofSound.

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