The first protocol for the use of lung ultrasound to quantitatively and reproducibly assess the degree of lung involvement in patients suspected of having COVID-19 infection has been published by a team of Italian experts with experience using the technology on the front line.
Particularly in Spain and Italy — where the pandemic has struck hardest in Europe — hard-pressed clinicians seeking to quickly understand whether patients with seemingly mild disease could be harboring more serious lung involvement have increasingly relied upon lung ultrasound in the emergency room.
Now Libertario Demi, PhD, head of the ultrasound laboratory, University of Trento, Italy, and colleagues have developed a protocol, published online March 30 in the Journal of Ultrasound Medicine, to standardize practice.
Their research, which builds on previous work by the team, offers broad agreement with industry-led algorithms and emphasizes the use of wireless, handheld ultrasound devices, ideally consisting of a separate probe and tablet, to make sterilization easy.
Firms such as the Butterfly Network, Phillips, Clarius, GE Healthcare, and Siemens are among numerous companies that produce one or more such devices, including some that are completely integrated.
Not Universally Accepted
However, lung ultrasound is not yet universally accepted as a tool for diagnosing pneumonia in the context of COVID-19 and triaging patients.
The National Health Service in England does not even mention lung ultrasound in its radiology decision tool for suspected COVID-19, specifying instead chest X-ray as the first-line diagnostic imaging tool, with CT scanning in equivocal cases.
But Giovanni Volpicelli, MD, University Hospital San Luigi Gonzaga, Turin, Italy, who has previously described his experience to Medscape Medical News, says many patients with COVID-19 in his hospital presented with a negative chest X-ray but were found to have interstitial pneumonia on lung ultrasound.
Moreover, while CT scan remains the gold standard, the risk of nosocomial infection is more easily controlled if patients do not have to be transported to the radiology department but remain in the emergency room and instead undergo lung ultrasound there, he stressed.
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 because 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.