Point of Care Ultrasound (PoCUS) during the Covid-19 pandemic – Is this point of care tool more efficacious than standard imaging?

Resident Clinical Pearl (RCP) May 2020

Dr. Colin Rouse– (PGY-3  CCFP Emergency Medicine) | Dalhousie University

and Dr. Sultan Alrobaian (Dalhousie PoCUS Fellow, Saint John, NB, Canada)

Reviewed by Dr. David Lewis

Case

A 70 year of woman present to the ED with a history of fever, cough and dyspnoea. After a full clinical assessment (with appropriate PPE), Lung PoCUS is performed.

Introduction

The Covid-19 Pandemic has created the largest international public health crisis in decades. It has fundamentally changed both societal norms and health care delivery worldwide. Changes have been implemented into resuscitation protocols including ACLS to prioritise appropriate donning of personal protective equipment (PPE) and consideration of resuscitation appropriateness prior to patient contact.¹ Equipment has been removed from rooms to limit cross-contamination between patients. In this Pearl we will explore why PoCUS should not be discarded as an unnecessary tool and should be strongly considered in the assessment of a potential Covid Patient.

Disclaimer: Given the novel nature of CoVid-19 there is a lack of RCT data to support the use of PoCUS. These recommendations are based solely on expert opinion and case reports until superior evidence becomes available.

Potential Benefits of PoCUS

• Lung PoCUS has increased sensitivity compared to conventional lung X-ray for known lung pathologies such as CHF⁴ and Pneumonia⁵ with similar specificities. Given that Pneumonia is the most common complication of Covid-19 it may help diagnose this complication in patients who have a normal CXR.
• PoCUS can be performed by the assessing physician limiting the unnecessary exposure to other health care providers such and Radiologic Technologists and other staff in the diagnostic imaging department.
• Lung PoCUS is low cost, repeatable and available in rural settings
• Once pneumonia is diagnosed other potential complications can be sought including VTE and cardiovascular complications.

The assessment of the potential Covid-19 patient.

First one must consider the potential risk for coronavirus transmission at each patient encounter and ensure proper PPE² for both oneself and the PoCUS device³.

Lung Ultrasound in the potential Covid-19 Patient

Technique

• Appropriate level PPE
• A low-frequency (3–5 MHz) curvilinear transducer
• Set Focus to Pleural Line and turn off machine filters (e.g THI) to maximize artifacts
• Scanning should be completed in a 12-zone assessment⁶
  • 2 anterior windows
  • 2 lateral windows
  • 2 posterior windows

Findings⁷

Mild Disease

• Focal Patchy B-lines in early disease/mild infection (May have normal CXR at this point)
• Areas of normal lung

Moderate/Severe Disease – Findings of bilateral Pneumonitis

• B-lines begin to coalesce (waterfall sign)
• Thickened and irregular pleura
• Subpleural Hypoechoic consolidation      +/- air bronchograms

Other Covid-19 Pearls

• Large/Moderate Pleural Effusion rarely seen in Covid-19 (consider another diagnosis) – Small peripleural effusions are common in COVID
• The virus has a propensity for the base of the posterior lung windows and it imperative to include these views in your assessment.

Example COVID PoCUS Videos⁸

Confluent B Lines and small sub pleural consolidation

Patchy B lines and Irregular pleura

Irregular pleura

Air Bronchogram

CT & ultrasonographic features of COVID-19 pneumonia⁹

It has been noted that lung abnormalities may develop before clinical manifestations and nucleic acid detection with some experts recommending early Chest CT for screening suspected patients.¹⁰ Obviously there are challenges with this recommendation mainly regarding feasibility and infection control. A group of researchers in China compared Ultrasound and CT findings in 20 patients with COVID-19. Their findings are summarized in the table below:

Their conclusion was that ultrasound has a major utility for management of COVID-19 due to its safety, repeatability, absence of radiation, low cost and point of care use. CT can be reserved for patients with a clinical question not answered by PoCUS. CT is required to assess for pneumonia that does not extend to the pleura. Scatter artifact from aerated lung obscures visualization of deep lung pathology with PoCUS. When PoCUS is sufficient it can be used to assess disease severity at presentation, track disease evolution, monitor lung recruitment maneuvers and prone positioning and guide decisions related to weaning of mechanical ventilation.

Learning Points

• Lung PoCUS is helpful in the initial assessment of the suspected or known COVID19 Patient
• Lung PoCUS may reveal pathology not visible on CXR
• Lung PoCUS can provide insight into COVID19 disease severity
• Lung PoCUS is a useful tool to track disease progression in COVID19

Lung PoCUS in COVID Deep Dive

Deep Dive Lung PoCUS – COVID 19 Pandemic

References

1. Edelson, D. P., Sasson, C., Chan, P. S., Atkins, D. L., Aziz, K., Becker, L. B., … & Escobedo, M. (2020). Interim Guidance for Basic and Advanced Life Support in Adults, Children, and Neonates With Suspected or Confirmed COVID-19: From the Emergency Cardiovascular Care Committee and Get With the Guidelines®-Resuscitation Adult and Pediatric Task Forces of the American Heart Association in Collaboration with the American Academy of Pediatrics, American Association for Respiratory Care, American College of Emergency Physicians, The Society of Critical Care Anesthesiologists, and American Society of …. Circulation.
2. COVID-19 – Infection Protection and Control. https://sjrhem.ca/covid-19-infection-protection-and-control/
3. Johri, A. M., Galen, B., Kirkpatrick, J. N., Lanspa, M., Mulvagh, S., & Thamman, R. (2020). ASE Statement on Point-of-Care Ultrasound (POCUS) During the 2019 Novel Coronavirus Pandemic. Journal of the American Society of Echocardiography.
4. Maw, A. M., Hassanin, A., Ho, P. M., McInnes, M., Moss, A., Juarez-Colunga, E., Soni, N. J., Miglioranza, M. H., Platz, E., DeSanto, K., Sertich, A. P., Salame, G., & Daugherty, S. L. (2019). Diagnostic Accuracy of Point-of-Care Lung Ultrasonography and Chest Radiography in Adults With Symptoms Suggestive of Acute Decompensated Heart Failure: A Systematic Review and Meta-analysis. JAMA network open, 2(3), e190703. https://doi.org/10.1001/jamanetworkopen.2019.0703
5. Balk, D. S., Lee, C., Schafer, J., Welwarth, J., Hardin, J., Novack, V., … & Hoffmann, B. (2018). Lung ultrasound compared to chest X‐ray for diagnosis of pediatric pneumonia: A meta‐analysis. Pediatric pulmonology, 53(8), 1130-1139.
6. Wurster, C., Turner, J., Kim, D., Woo, M., Robichaud, L. CAEP. COVID-19 Town Hall April 15: Hot Topics in POCUS and COVID-19. https://caep.ca/covid-19-town-hall-april-15-hot-topics-in-pocus-and-covid-19/
7. Riscinti, M. Macias, M., Scheel, T., Khalil, P., Toney, A., Thiessen, M., Kendell, J. Denver Health Ultrasound Card. http://www.thepocusatlas.com/covid19
8. Images obtained from. Ultrasound in COVID-19. The PoCUS Atlas. http://www.thepocusatlas.com/covid19
9. Peng, Q., Wang, X. & Zhang, L. Findings of lung ultrasonography of novel corona virus pneumonia during the 2019–2020 epidemic. Intensive Care Med (2020). https://doi.org/10.1007/s00134-020-05996-6
10. National Health Commission of the people’s Republic of China. Diagnosis and treatment of novel coronavirus pneumonia (trial, the fifth version)[EB/OL]. (2020-02-05)[2020-02-06]. http://www.nhc.gov.cn/yzygj/s7653p/202002/3b09b894ac9b4204a79db5b8912d4440.shtml