First Protocol on How to Use Lung Ultrasound to Triage COVID-19
Experts Share Experience of Lung Ultrasound in COVID-19
In developing and publishing their protocol, Demi, senior author of the article, and other colleagues from the heavily affected cities of Northern Italy, say their aim is “to share our experience and to propose a standardization with respect to the use of lung ultrasound in the management of COVID-19 patients.”
They reviewed an anonymized database of around 60,000 ultrasound images of confirmed COVID-19 cases and reviewers were blinded to patients’ clinical backgrounds.For image acquisition, the authors recommend scanning 14 areas in each patient for 10 seconds, making the scans intercostal to cover the widest possible surface area.
They advise the use of a single focal point on the pleural line, which they write, optimizes the beam shape for observing the lung surface.
The authors also urge that the mechanical index (MI) be kept low, as high MIs sustained for long periods “may result in damaging the lung.”
They also stress that cosmetic filters and modalities such as harmonic imaging, contrast, doppler, and compounding should be avoided, alongside saturation phenomena.
What Constitutes Intermediate Disease?
Once the images have been taken, they are scored on a 0-3 scale for each of the 14 areas, with no weighting on any individual area.
A score of 0 is given when the pleural line is continuous and regular, with the presence of A-lines, denoting that the lungs are unaffected.
An area is given a score of 3 when the scan shows dense and largely extended white lung tissue, with or without consolidations, indicating severe disease.
At both ends of this spectrum, there is agreement between the Italian protocol and an algorithm developed by the Butterfly Network.
However, the two differ when it comes to scoring intermediate cases. On the Butterfly algorithm, the suggestion is to look for B-lines, caused by fluid and cellular infiltration into the interstitium, and to weigh that against the need for supplementary oxygen.
The Italian team, in contrast, says a score of 1 is given when the pleural line is indented, with vertical areas of white visible below.
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