Lung ultrasound can aid in the risk stratification, early diagnosis, and management of respiratory failure from COVID-19. For some basics on how to perform a lung ultrasound please review Segun’s post on how to obtain BAT views.
There are 2 different phenotypes for COVID-19 ARDS patients. Are there 2 different lung ultrasound patterns as well?
Two different types of phenotypes have been described.
- The L-type has preserved lung compliance with disproportionate hypoxia. CT chest shows typical peripheral ground glass opacities. Lung ultrasound typically shows B lines with some adjacent spared areas with an A line pattern. Some also debate that many of these patients have a “silent hypoxemia” (preserved compliance state in the early phase of respiratory failure but eventually progress to a more typical ARDS picture with low compliance).
- The H-type is a more typical ARDS. CT shows dense consolidations with lung ultrasound showing loss of aeration of the lower lobes.
Let’s see some images and talk about some COVID-19 cases
Image 1. Lung ultrasound/anterior lung. 43 year old with COVID-19 respiratory failure requiring HFNC. CT scan showed diffuse peripheral ground-glass opacities. Image 1 is a lung ultrasound image showing an irregular/thick pleural line with confluent B lines with adjacent areas of the spared lung. (sometimes these spared areas can have a A-line pattern ). https://www.youtube.com/watch?v=TjyRw32vtN0
Image 2. Lung ultrasound anterior lung. 73-year-old male with COVID- ARDS. CT scan chest showed diffuse ground-glass opacities. Image 2 is a lung ultrasound image showing an interrupted irregular pleural line with sub-pleural small consolidations and associated B lines. This is commonly seen in COVID patents especially in patients with ARDS.
Image 3. Lung ultrasound at the posterolateral alveolar/pleural syndrome (PLAPS) point. The “Tissue-like” sign can be appreciated. A tissue-like sign is a representation of complete loss of aeration to the point that the sonographic appearance of the lung matches that of other tissues such as the liver. Air bronchograms and a lung pulse can help differentiate viral pneumonia vs. atelectasis. Based on this lung ultrasound finding, APRV was initiated leading to gradual improvement in lung recruitment and oxygenation. https://youtu.be/Y9qKpAShdto
So are there different lung ultrasound findings for the different phenotypes of COVID patients?
- Confluent B lines with adjacent areas of the spared lung with an A-line pattern. These findings correlate with ground glass opacities on the CT chest. These are seen in both “L” and “H” phenotypes.
- Subpleural consolidations and irregular pleural lines are commonly seen in both phenotypes of COVID-19 ARDS patients.
- Dense consolidation with tissue-like sign and PLAPS can be seen in COVID 19 patients. Some of these patients who have atelectasis may benefit from a ventilator strategy with higher mean airway pressures. This is seen more in the “H-type” COVID phenotype.
- Large pleural effusions are atypical for COVID-19 patients.
So for which patient should I perform a lung ultrasound? Is there a situation in which I should not perform a lung ultrasound?
- Lung ultrasound ideally should be performed if it would change your clinical management or to answer a clinical question.
- In the ED, if you have decided to admit a patient to the medicine floor or the ICU based on your clinical assessment, then a thoracic ultrasound should not change that decision. A patient with typical lung ultrasound findings may be at a higher risk for worsening disease so it may help with risk stratification.
- In the ED if you have decided to discharge a patient home, then a lung ultrasound should not change that decision. https://pubmed.ncbi.nlm.nih.gov/32976318/
- On the medicine floor, patients with typical lung ultrasound signs may be at a higher risk for worsening disease.
- In the ICU, lung ultrasound can help guide ventilator management. A patient with typical loss of aeration of the lower lobes (i.e. atelectasis ) may benefit from a ventilator strategy with higher mean airway pressures ( image 3 ).
Glossary of Terms
- ARDS- Acute Respiratory Distress Syndrome
- PLAPS- Postero Lateral Alveolar Pleural syndrome
- APRV- Airway Pressure Release Ventilation
- Jackson K, Butler R, Aujayeb ALung ultrasound in the COVID-19 pandemicPostgraduate Medical Journal 2021;97:34-39.
- Karagöz A, Sağlam C, Demirbaş HB, Korkut S, Ünlüer EE. Accuracy of Bedside Lung Ultrasound as a Rapid Triage Tool for Suspected Covid-19 Cases. Ultrasound Q. 2020 Dec;36(4):339-344. doi: 10.1097/RUQ.0000000000000530. PMID: 32976318.