Interpreting POCUS findings in non-COVID-19 lung diseases

7th Jan 2021

One of the great things about lung point-of-care ultrasound (POCUS) is that it can help you make a range of diagnoses, not just a diagnosis of COVID-19!

You might suspect COVID-19 in a patient, but that doesn’t mean you’ll find it. You have to keep an open mind to diagnose other diseases, because lung ultrasound findings are not specific for COVID-19. This is especially important in patients who have other comorbidities! Medmastery note.

Remember, sonographic B-lines are produced by diseases that affect the interstitium of the alveoli, so they can be seen in a range of diseases. For example, both COVID-19 and pulmonary edema can produce diffuse bilateral B-lines. 

Lung ultrasound scan with B-lines beside illustrations of the interstitium and a lung with pulmonary edema.

Figure 1. An ultrasound scan of a lung with sonographic B-lines can suggest diseases that affect the interstitium of the alveoli such as COVID-19 and pulmonary edema.

So, let’s discuss some examples where the lung POCUS findings are similar to those found in COVID-19! 

 

Pulmonary edema (as a result of congestive heart failure)

First, let’s consider a patient with pulmonary edema as a result of congestive heart failure (CHF). Clinical history, physical examinations, and lab results must be integrated to help distinguish the difference between the B-lines seen in this patient versus ones you might see in COVID-19.

Looking closely at the pleura may help tip you off that the B-lines you’re seeing are cardiogenic, and not from COVID-19 or a primary pulmonary etiology.

B-lines in CHF tend to arise off the pleura directly, and small consolidations and irregular pleura are uncommon. You could consider using M-mode to help you appreciate the features of the pleura more clearly.

Image of a lung ultrasound scan of pulmonary edema with labels on the pleura and B-lines.

Figure 2. B-lines and a fragmented pleura can be seen on lung point-of-care ultrasound (POCUS) in patients with congestive heart failure (CHF). B-lines in CHF (and not COVID-19) tend to arise off the pleura directly, and small consolidations and irregular pleura are uncommon.

Check out this short video clip from our COVID Mini: Lung US Course to see how B-lines in the lungs of a patient with congestive heart failure (CHF) differ from those seen in a patient with COVID-19:

 

 

Pneumonia

Pneumonia is a common cause of dyspnea and hypoxia—especially when the patient presents with a fever. Most pneumonias start at the lung periphery, and so it will affect the pleura. Therefore, lung ultrasound is an excellent diagnostic test for pneumonia!

On a lung ultrasound image, you will be looking for a larger, dominant consolidation, possible adjacent B-lines, or a parapneumonic effusion. As well, bacterial pneumonia is typically a unilateral process, not bilateral (as seen in COVID-19).

Pneumonic lung ultrasound scan with a label on a large dominant consolidation.

Figure 3. To identify pneumonia in a lung ultrasound scan, look for a large dominant consolidation. 

Check out this short video clip from our COVID Mini: Lung US Course to see how consolidation in the lungs of a patient with pneumonia differs from those seen in a patient with COVID-19:

 

 

Pleural effusion

Large pleural effusions are not typical of COVID-19. If you find one (which would appear on ultrasound as anechoic space above the diaphragm and spine sign), consider an alternative diagnosis.

Lung ultrasound scan with labels on a pleural effusion, lung tip, diaphragm, and spine sign.

Figure 4. An ultrasound scan with a large pleural effusion above the diaphragm and spine sign suggests an alternative diagnosis to COVID-19. 

Check out this short video clip from our COVID Mini: Lung US Course to see a large pleural effusion, atypical for a patient with COVID-19:

 

 

Pneumothorax

Pneumothorax is another classic diagnosis to make with lung ultrasound. However, an alternative explanation for someone short of breath could be an older person with chronic obstructive pulmonary disease or a young person with dyspnea. 

For example, an ultrasound of a patient’s right lung might show no movement or lung sliding on the right part of the pleura. This is sensitive—but not completely specific—for pneumothorax. But, on the left of the pleura, you see the movement as the lung slides in. This is a lung point sign and specific for pneumothorax. 

Lung ultrasound scan of a pneumothorax lung with a label on the lung point sign.

Figure 5. The lung point sign is specific for pneumothorax. The lung point is the junction between lung sliding and absent lung sliding, visualized on an US scan.

Check out this short video clip from our COVID Mini: Lung US Course to see an example of the lung point sign (a sign specific for pneumothorax) on a POCUS scan:

 

 

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Bronchiolitis (and other viral illnesses)

Other viral illnesses with lung involvement can have a similar appearance to COVID-19 on a lung ultrasound! For example, in a patient with bronchiolitis, you can see B-lines, irregular pleura, and small consolidations. Again, we have to think about prevalence and pre-test probability within the community to determine the likelihood of a COVID-19 diagnosis.

Bronchiolitis lung ultrasound scan with labels on B-lines, irregular pleura, and small consolidations.

Figure 6. Ultrasound scans of a child with bronchiolitis depicting B-lines, irregular pleura, and small consolidations. 

Check out this short video clip from our COVID Mini: Lung US Course to see how bronchiolitis can have a similar appearance on US to COVID-19:

 

 

Pulmonary fibrosis (and other interstitial lung diseases)

Interstitial lung disease, such as pulmonary fibrosis, produces a very similar appearance to COVID-19. Always respect the clinical context and history of your patient when interpreting your lung ultrasound! 

Image of a lung ultrasound scan of interstitial lung disease.

Figure 7. An ultrasound scan of interstitial lung disease with a similar appearance to COVID-19. 

Check out this short video clip from our COVID Mini: Lung US Course to see how pulmonary fibrosis, an interstitial lung disease, can appear similar on US to COVID-19:

 

 

Acute respiratory distress syndrome (ARDS)

COVID-19 can cause acute respiratory distress syndrome (ARDS), and the appearance of severe COVID-19 and ARDS on lung ultrasound will converge. This includes the presence of B-lines, small consolidations, irregular pleura, and areas of spared lung.

If you see this pattern, but you weren't suspecting COVID-19, keep an open mind for an alternative cause of ARDS. Alternatively, add COVID-19 onto the differential diagnosis.

Lung ultrasound scan of acute respiratory distress syndrome (ARDS) with labels on consolidations, irregular pleura, B-lines, and A-lines.

Figure 8. An ultrasound scan of acute respiratory distress syndrome (ARDS) can mimic the etiology of severe COVID-19 including B-lines, small consolidations, irregular pleura, and areas of spared lung. 

Check out this short video clip from our COVID Mini: Lung US Course to see how ARDS appears on a POCUS scan:

 

Table of common lung point-of-care ultrasound (POCUS) findings for COVID-19, pulmonary edema, pneumonia, pleural effusion, pneumothorax, bronchiolitis, interstitial lung disease, and acute respiratory distress syndrome (ARDS).

Table 1. Summary of common lung point-of-care ultrasound findings in COVID-19 and other pulmonary diseases that should be considered as part of your differential diagnosis when faced with a patient with shortness of breath and respiratory failure.

 

Cardiac causes

Of course, there are cardiac causes, such as tamponade in patients with pericardial effusions. Point-of-care limited echocardiography is a valuable addition to your lung scans!

Heart ultrasound scan highlighting a cardiac tamponade.

Figure 9. Heart ultrasound scan highlighting cardiac causes (such as tamponade) of pericardial effusion. 

Check out this short video clip from our COVID Mini: Lung US Course to see an example of a heart US showing cardiac tamponade:

 

The big takeaway is that diseases other than COVID-19 can cause shortness of breath and respiratory failure. Point-of-care ultrasound (lung and heart) can help you make these differential diagnoses! You must remember to consider the history and clinical context, especially since the POCUS findings for COVID-19 are non-specific. 

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