How to perform lung POCUS for your patients with COVID-19

7th Jan 2021

Point-of-care ultrasound (POCUS) is a powerful diagnostic tool for evaluating patients with suspected COVID-19, but it’s essential to know how to scan your patients during the pandemic. Even if you’re a lung ultrasound expert, there are some important differences when scanning patients suspected of having COVID-19

Now, let’s take a closer look at how to get high-quality diagnostic images from a lung scan! 

 

Tools for lung POCUS in patients with COVID-19

There are four types of ultrasound tools that can be used for lung POCUS: 

  1. Low-frequency curvilinear probe
  2. Handheld portable system 
  3. High-frequency linear transducer 
  4. Phased array or cardiac probe  

For POCUS, you need a transducer that allows you to scan at depth. Ideally, you want access to a low-frequency and high-frequency linear transducer. A high-frequency linear transducer is not necessary but can help with examining the pleura and more superficial structures. Phased array or cardiac probes are also possible to use if needed. 

Four ultrasound probes low-frequency curvilinear probe, a handheld portable ultrasound, high-frequency linear transducer, and phased array or cardiac probe. Illustration.

Figure 1. The four ultrasound tools that can be used for lung point-of-care ultrasound (POCUS) include low-frequency curvilinear probes, handheld portable ultrasounds, high-frequency linear transducers, and phased array or cardiac probes. 

 

How to set up an ultrasound machine for lung POCUS

There are five steps for setting up the machine for a POCUS lung scan:

  1. Select the low-frequency transducer. 
  2. Choose the lung ultrasound preset.
  3. Turn off effects (e.g., tissue harmonics and multi-beam). 
  4. Increase the depth to 18–20 cm. 
  5. Make sure you and your patient are comfortable. 

 

How to perform lung POCUS in your patients with COVID-19

There are four basic steps for scanning your patient with an ultrasound machine:

  1. Orient the transducer vertically on the midclavicular line and slide down. 
  2. Repeat this action on the other side of the body.
  3. Scan upwards at the midaxillary line, starting at the costal margin and diaphragm. Repeat this action on the other side of the body.
  4. For COVID-19 diagnostic scans, scan posteriorly. 

The posterior scan is different from other lung ultrasound applications that you may know. You may need to ask an assistant to help support the patient to properly scan their back! 

Step-by-step illustration of a patient being scanned with a transducer on the midclavicular and midaxillary lines, and posteriorly.

Figure 2. To scan your patient, 1) orient the transducer vertically on the midclavicular line and slide down, 2) repeat this action on the other side, 3) scan upwards at the midaxillary line (on both sides) starting at the costal margin and diaphragm, and 4) for COVID-19 diagnostic scans, scan posteriorly. 

 

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What will you see on a lung POCUS scan?

A-lines

In an ultrasound image of a normal lung, the ribs cast acoustic shadows, the hyperechoic pleura just below the ribs is smooth and linear, and the A-lines are visible below the pleura. The A-lines are an artifact arising from sound reverberating between the two pleural layers, which is a normal finding in well-aerated lungs!

US scan of normal lung in the midclavicular line with labels on pleura and A-lines.

Figure 3. Ultrasound scan of a normal lung in the midclavicular line highlighting the pleura and A-lines.

In a lung point-of-care ultrasound (POCUS) of a patient with suspected COVID-19, be aware of axis versus off-axis scans. It is important to be perpendicular to the pleura. If not, then the pleura might look falsely thick. Medmastery note.

Pleura and B-lines

In the midaxillary line, as you fan the probe, the pleura becomes thicker and more indistinct. You will want to move the probe to make the pleura look as thin and linear as possible—with the ribs adjacent to the pleura.

US image of normal lung in the midaxillary line with a label on the pleura.

Figure 4. Ultrasound scan of a normal lung in the midaxillary line highlighting the pleura. 

If you find or suspect a superficial abnormality at the pleura, then you may need to use the linear transducer to take a closer look. The transducer will allow you to reduce the depth to 5 cm—or less—and gives you better resolution.

For example, with the curvilinear transducer at 18 cm depth, the scan shows sonographic B-lines, and you can already see that the pleura looks linear and smooth. 

18 cm deep lung ultrasound scan with the curvilinear transducer with labels on B-lines.

Figure 5. Lung ultrasound scan with the curvilinear transducer at 18 cm depth highlighting B-lines. 

Small consolidations

At lower depths, the pleura can also be examined to appreciate its irregularities, small consolidations, and adjacent pleural fluid. 

Low-depth lung ultrasound scan with the curvilinear transducer with labels on pleural fluid and a consolidation.

Figure 6. Lung ultrasound scan with the curvilinear transducer at depths lower than 18 cm highlighting the pleura’s irregularities, small consolidations, and adjacent pleural fluid. 

 

That’s it for now. If you want to improve your understanding of key concepts in medicine, and improve your clinical skills, make sure to register for a free trial account, which will give you access to free videos and downloads. We’ll help you make the right decisions for yourself and your patients.

Recommended reading

  • Dargent, A, Chatelain, E, Kreitmann, L, et al. 2020. Lung ultrasound score to monitor COVID-19 pneumonia progression in patients with ARDS. PLoS One15: e0236312. PMID: 32692769
  • Kim, DJ, Jelic, T, Woo, MY, et al. 2020. Just the facts: Recommendations on point-of-care ultrasound use and machine infection control during the coronavirus disease 2019 pandemic. CJEM22: 445–449. PMID: 32268930
  • Long, B, Brady, WJ, Koyfman, A, et al. 2020. Cardiovascular complications in COVID-19. Am J Emerg Med38: 1504–1507. PMID: 32317203
  • Mongodi, S, Orlando, A, Arisi, E, et al. 2020. Lung ultrasound in patients with acute respiratory failure reduces conventional imaging and health care provider exposure to COVID-19. Ultrasound Med Biol46: 2090–2093. PMID: 32451194
  • Pare, JR, Camelo, I, Mayo, KC, et al. 2020. Point-of-care lung ultrasound is more sensitive than chest radiograph for evaluation of COVID-19. West J Emerg Med21: 771–778. PMID: 32726240
  • Soldati, G, Smargiassi, A, Inchingolo, R, et al. 2020. Is there a role for lung ultrasound during the COVID-19 pandemic? J Ultrasound Med39: 1459–1462. PMID: 32198775
  • Soldati, G, Smargiassi, A, Inchingolo, R, et al. 2020. Proposal for international standardization of the use of lung ultrasound for patients with COVID-19: A simple, quantitative, reproducible method. J Ultrasound Med39: 1413–1419. PMID: 32227492
  • Volpicelli, G, Lamorte, A, and Villén, T. 2020. What’s new in lung ultrasound during the COVID-19 pandemic. Intensive Care Med46: 1445–1448. PMID: 32367169
  • Volpicelli, G and Gargani, L. 2020. Sonographic signs and patterns of COVID-19 pneumonia. Ultrasound J12: 22. PMID: 32318891
  • Xing, C, Li, Q, Du, H, et al. 2020. Lung ultrasound findings in patients with COVID-19 pneumonia. Crit Care24: 174. PMID: 32345353