How can lung POCUS be used for follow-up evaluations for patients with COVID-19?
Lung point-of-care ultrasound (POCUS) is an extremely useful tool for monitoring the progression of COVID-19 and detecting secondary complications associated with COVID-19 progression.
Monitoring disease progression in patients with COVID-19
Let’s say you’re looking after someone with an established diagnosis of COVID-19: they might be admitted to the hospital, emergency department, or clinic several days after their initial diagnosis.
The COVID-19 infection can take anywhere from days to weeks to resolve, and people can worsen over that time. Luckily, POCUS can help you monitor these patients!
If you have been following your patients longitudinally in the hospital with daily scans, you should have a sense of what their lungs looked like on ultrasound at baseline.
Seeing a worsening of the typical COVID-19 findings on lung ultrasound suggests that the clinical changes are due to disease progression. Tracking the disease progression can help you determine if the patient is going to get worse in the coming days.
Figure 1. Follow your patient longitudinally in the hospital with daily scans. Seeing a worsening of the typical COVID-19 findings on lung ultrasound from baseline can be associated with disease progression.
Check out this short video clip from our COVID Mini: Lung US Course to see how typical COVID-19 US findings change over time:
However, don’t base your decisions solely on the ultrasound findings! Put them together with the symptoms, clinical findings, and lab data.
For example, some patients may have terrible looking lungs, but if they are later in their disease course and have proven stable over time, they can be managed as an outpatient.
On the other hand, if you see a new progression of B-lines it might be wise to observe the patient more closely—particularly if they are early in their disease course.
Detecting secondary complications in patients with COVID-19
Lung ultrasound is also a great tool for detecting secondary complications of COVID-19. We’re still learning about COVID-19, and we now understand that it can produce a range of secondary complications.
A patient who has worsening symptoms or hypoxia might have an alternative explanation other than COVID-19 progression. A super-infection with pneumonia is a possible complication. POCUS can help us evaluate the lungs for these infections.
During a repeat lung scan, look for a larger tissue-like consolidation that may produce a spine sign, where the spine is visible above the diaphragm. Larger consolidations from pneumonia are distinct from the smaller consolidations that are typical in COVID-19.
Figure 2. A lung ultrasound scan for a patient with pneumonia will show larger tissue-like consolidations.
The patient might also have a larger parapneumonic effusion, which is uncommon in COVID-19 scans.
Check out this short video clip from our COVID Mini: Lung US Course to see what pneumonia looks like on a POCUS scan:
COVID-19 is also known to predispose patients to thromboembolic disease. So, pulmonary embolism is on the differential diagnosis for worsening hypoxia or dyspnea in a patient with COVID-19.
For an unstable patient, or during the re-evaluation of a patient with COVID-19, point-of-care ultrasound can be used to look for secondary evidence of pulmonary embolism causing right heart strain.
To do this, we need a view of the heart from the apical four-chamber window obtained with a phased array or cardiac probe.
Set the probe at the point of maximal impulse (PMI) on the chest, just below the nipple. If possible, place the patient in a left lateral decubitus position.
For most point-of-care ultrasound users, the indicator dot on the ultrasound screen will be on the left. This means that the indicator dot on the probe will face upwards.
Figure 3. The apical four-chamber view requires the phased array or cardiac probe positioned at the point of maximal impulse with the blue indicator dot facing upwards.
In this view, the right side of the heart will be on the left side of the image.
In a normal heart, the right ventricle appears smaller in the horizontal dimension than the left ventricle (at the level of the valves). For point-of-care ultrasound, we expect the size difference to be less than a 1:1 ratio. In the vertical translation, the right ventricle will appear to be bouncing up and down.
Figure 4. Normal heart ultrasound scan in the apical four-chamber view showing that the right ventricle (RV) is smaller than the left ventricle (LV) in the horizontal dimension at the level of the valves. For point-of-care ultrasound, we expect the size difference to be less than a 1:1 ratio.
In a patient with a large pulmonary embolism, the right ventricle will be larger than the size of the left ventricle!
Figure 5. Ultrasound showing an enlarged right ventricle (RV) in a patient with a large pulmonary embolism at the apical four-chamber.
Right ventricular dysfunction
Notably, in patients with COVID-19 with worsening hemodynamics or hypoxemia, there may be other causes for an enlarged right ventricle.
Some critically ill patients may develop multifactorial right ventricular dysfunction. In addition to pulmonary embolism, this dysfunction should be added to your differential diagnosis for an enlarged right ventricle.
Figure 6. Critically ill patients with COVID-19 may develop a multifactorial right ventricular dysfunction. Multifactorial right ventricular dysfunction should be added to your differential diagnosis for an enlarged right ventricle.
Acute respiratory distress syndrome
In acute respiratory distress syndrome (ARDS), there is decreased venous return due to mechanical ventilation with increased intrathoracic pressure and increasing right ventricle afterload from increasing transpulmonary pressure.
Figure 7. In acute respiratory distress syndrome (ARDS), there is decreased venous return due to mechanical ventilation with increased intrathoracic pressure and increasing right ventricle afterload from increasing transpulmonary pressure.
Patients with microthrombi in the pulmonary vessels will have increased pulmonary vascular resistance from vasoconstriction, which is related to hypoxia and hypercapnia. In turn, impaired right ventricular function can impair left ventricular function by paradoxical septal movement and ventricular interdependence.
COVID-19 patients with right ventricular dysfunction—or even an enlarged right ventricle—have higher mortality.
Examples of other echocardiography findings in right ventricular dysfunction include paradoxical septal motion (also known as McConnell’s sign) and decreased tricuspid annular plane systolic excursion (TAPSE).
Check out this short video clip from our COVID Mini: Lung US Course to see examples of right ventricular dysfunction (paradoxical septal motion, or McConnell’s sign, and tricuspid annular plane systolic excursion, or TAPSE) seen in patients with COVID-19:
COVID-19 can also cause myocarditis. Even limited point-of-care echocardiography, such as handheld echocardiography (HHE), can help you detect decreased contractility to help support this differential diagnosis.
Check out this short video clip from our COVID Mini: Lung US Course to see an example of myocarditis on a POCUS lung scan from a patient with COVID-19:
To learn more about COVID-19 and cardiac dysfunctions, check out another fascinating course on COVID-19, the COVID Mini: Handheld Echocardiography!
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