Author: Nova Panebianco, MD, MPH, EM Ultrasound Division Director, Ultrasound Fellowship Director, Associate Professor, Department of Emergency Medicine, University of Pennsylvania
Patients with suspected infection with COVID-19 may have traditional indications for point-of-care ultrasound (POCUS); however, it is becoming clear that there are sonographic patterns in this cohort that may be even more amenable for diagnosis and management with POCUS. This may be particularly important when rapid COVID testing is limited, when patient volumes outstrip the institution’s resources, or when the patient is too unstable to have imaging beyond what is available at the bedside.
The following four categories of POCUS have been most discussed in the COVID ultrasound community:
The sensitivity of lung ultrasound (LUS) for COVID-19 is not clearly defined. Specificity is likely low as the findings seen in COVID-19 patients may also be seen in patients with other conditions (eg, CHF, pneumonia, interstitial lung disease). Posterior lung fields, which are not always part of a standard LUS, may be more often positive in COVID-19 patients. LUS should not be used alone as a diagnostic test, but rather integrated into the sum of available clinical data.
Author: Liu R, et al
Ultrasound of the lung utilizes artifacts and findings at the lung periphery and has been shown to identify heart failure, ARDS, and pneumonia, using POCUS. Lung ultrasound findings in a series of 20 patients with COVID-19 included thickening and irregularity of the pleural line, a variety of B-line patterns, and subpleural consolidations, with pleural effusions being rare.
A recent letter in Radiology reported ultrasound in 12 patients with 4 to 10 days of COVD-19 infection without severe respiratory illness, with all patients displaying a “diffuse B-pattern with spared areas.” The authors “strongly recommend the use of bedside US for the early diagnosis of COVID-19 pneumonia.” While these results are preliminary, they suggest ultrasound findings in COVID-19 are likely more common than findings on plain chest radiography and may be characteristic of COVID-19.
For more information, refer to the “ASE Statement on Point-of-Care Ultrasound (POCUS) During the 2019 Novel Coronavirus Pandemic.”
Additional resources include:
Growing evidence suggests that some patients with severe COVID-19 infection develop cardiomyopathy. It is unclear if this represents a viral cardiomyopathy, is stress-induced, or is secondary to cytokine storm. In a case series of 21 patients in the Evergreen Hospital in Kirkland, Washington, 33% (n = 7) developed cardiomyopathy.1 In a case report of 138 hospitalized COVID-19 patients, 16.7% developed arrhythmia, and 7.2% experienced acute cardiac injury.2 While many emergency medicine physicians are familiar with basic echocardiography for global left ventricular assessment and can recognize a diminished ejection fraction, the assessment for regional wall motion abnormalities is typically outside the scope of practice. Comprehensive echo in critically ill COVID-19 patients may increase the risk of disease exposure to echocardiography technicians and pose an infection control risk, as the ultrasound machine is brought in and out of rooms.
In a brief review of the literature, pericardial effusion/tamponade does not appear to be higher in COVID-19 patients than in other critically ill patients. However, this condition should be considered in any critically ill patient with unexplained hypotension. The assessment for pericardial effusion and tamponade is within the scope of emergency medicine echocardiography practice. The decision to obtain a comprehensive echo versus clinical decision making off of POCUS images will likely vary by institutional practice. Having POCUS images available for consultant review may limit unnecessary additional testing.
Some patients with severe COVID-19 infection develop a prothrombotic state, which may lead to DVT and PE. Assessment for right heart strain is within the scope of emergency medicine practice. The assessment of acute right heart strain versus chronic is more challenging. A baseline POCUS echo at the time of admission should be considered, as the development of right heart strain in a patient who did not have these findings earlier can assist in the diagnosis.
For additional information, see EMCrit’s Internet Book of Critical Care for COVID-19.
COVID-19 patients may develop a prothrombotic state, putting them at risk for DVT and PE, above the standard risk of hospitalization and immobility. Two-zone, femoral and popliteal, ultrasound of the lower extremity for DVT is within the scope of emergency medicine practice. In one study, a rapidly rising D-dimer was a predictor of COVID-DIC, and patients with a D-Dimer over 1,000 were 20 times more likely to die than patients with levels below this threshold.1 DVT prophylaxis should be maintained, provided there are no contraindications, and these patients may need higher doses of prophylactic heparin. Therapeutic anticoagulation with heparin for patients with D-dimer levels over 200 ng/mL has been suggested but is unproven.2,3
Ultrasound for procedural guidance is the standard of care for many invasive actions. COVID-19 patients will likely require several procedures as part of their care including, but not limited to, central venous access, arterial lines, thoracentesis, and paracentesis. The use of hand-held devices that can be easily covered, and cleaned, should be strongly considered. However, the decision to use these ultra-portable devices comes with the challenge of a small screen, where to put the screen when doing the procedure, and in some cases, inferior image quality compared to cart-based machines.
For more information, see the field guide section on "Ultrasound Cleaning."
Consider using hand-held ultrasound devices exclusively in COVID-19 suspected or confirmed patients. These ultra-portable devices are easier to cover, and clean, than cart-based devices. However, it should be noted that for some patients and conditions, the features available on cart-based devices (eg, spectral Doppler) may demand that these machines be brought to the bedside.