How does lung POCUS findings help the initial evaluation of COVID-19 patients?

With the knowledge of COVID-19’s appearance on lung ultrasound, as well as alternative lung disease diagnoses—let’s learn how to make an initial evaluation of a patient with suspected COVID-19 using point-of-care ultrasound (POCUS). 

 

Lung POCUS can help you confirm a COVID-19 diagnosis

First, let’s quickly review some of the presentations that definitely indicate the need for a lung point-of-care ultrasound (POCUS): 

1. Undifferentiated hypoxia 
2. Dyspnea 
3. Shock
4. Unstable for transfer   

^{Figure 1. Point-of-care ultrasound (POCUS) for patients with absolute indications for lung POCUS can help clinicians confirm a preliminary diagnosis of COVID-19.} 

With these indications, if you see lung ultrasound findings typical of COVID-19 (e.g., B-lines, irregular pleura, small consolidations, and involvement of both lungs) with a moderate or higher pre-test probability, you can be fairly confident in a preliminary diagnosis of COVID-19.

We are still learning about COVID-19, as well as the sensitivity of our tests, including lung ultrasound. 

The best data so far shows that some patients—who are sick enough to be hospitalized—will still have a normal lung ultrasound. So, you can’t totally exclude COVID-19 even if the lung ultrasound looks fine, especially if your pre-test probability is now very low. One study from China reported that 10% of their cohort had a normal lung ultrasound at the time of hospitalization and diagnosis!

We don’t know the exact sensitivity and specificity of lung ultrasound, but it appears that sensitivity improves with worsening disease and more lung ultrasound findings.

 

Lung POCUS can help you make decisions about patient care

Now, let’s revisit some of the relative indications for a lung ultrasound scan: 

1. Your patient is clinically COVID-19 positive, but disposition isn’t certain.
2. Your patient is clinically COVID-19 positive, but no other testing is available or planned. 
3. You are experiencing a large volume of patients where the emergency room is full of possible COVID-19 cases and the staff cannot keep up!

^{Figure 2.  Point-of-care ultrasound (POCUS) for patients with relative indications for lung POCUS can help clinicians make appropriate treatment decisions based on the findings.}  

Let’s first address the population where you’re uncertain about disposition. Should the patient be sent home, or do they require admission? If they require hospitalization, should they be on the floor or do they need a bed in the intensive care unit? 

For patients with uncertain dispositions, a scan that shows findings typical of COVID-19 might push you to be more conservative. Or, consider observing for a bit longer before making a decision, since we know that these patients can deteriorate quickly.

For the other two populations, if you see findings typical of COVID-19, then you’ve provided more support for your diagnosis and impression! Remember that in these populations, a normal lung ultrasound does not exclude COVID-19. It will support your decision to send the patient home with return precautions if they are otherwise appropriate for discharge.

 

Limitations of diagnosing COVID-19 with lung POCUS 

We still don’t know enough about the performance of lung ultrasound in mild COVID-19 disease—especially early on in the disease.

If patients are presenting early with non-respiratory symptoms and are young or at a low risk for poor outcomes, we might not expect that there would be pulmonary involvement, especially without dyspnea or cough.