We performed lung ultrasonography on 20 patients with COVID-19 using a 12-zone method [3].

Characteristic findings included the following:

1. Thickening of the pleural line with pleural line irregularity; 2. B lines in a variety of patterns including focal, multifocal, and confluent; 3. Consolidations in a variety of patterns including multifocal small, non-translobar, and translobar with occasional mobile air bronchograms; 4. Appearance of A lines during recovery phase; 5. Pleural effusions are uncommon.

The observed patterns occurred across a continuum from mild alveolar interstitial pattern, to severe bilateral interstitial pattern, to lung consolidation. Table 1 summarizes typical lung ultrasonography finds in patients with COVID-19 respiratory disease in comparison with chest CT findings. Typical lung ultrasonography images are shown in the supplementary material (Supplementary Fig. 1.)

Table 1 CT and ultrasonographic features of COVID-19 pneumonia Full size table

The findings of lung ultrasonography features of SARS-CoV-2 pneumonia/ARDS are related to the stage of disease, the severity of lung injury, and comorbidities. The predominant pattern is of varying degrees of interstitial syndrome and alveolar consolidation, the degree of which is correlated with the severity of the lung injury. A recognized limitation of lung ultrasonography is that it cannot detect lesions that are deep within the lung, as aerated lung blocks transmission of ultrasonography, i.e., the abnormality must extend to the pleural surface to be visible with on ultrasonography examination. Chest CT is required to detect pneumonia that does not extend to the pleural surface.

Based upon our experience, we consider that lung ultrasonography has major utility for management of COVID-19 with respiratory involvement due to its safety, repeatability, absence of radiation, low cost and point of care use; chest CT may be reserved for cases where lung ultrasonography is not sufficient to answer the clinical question. We find there is utility of lung ultrasonography for rapid assessment of the severity of SARS-CoV-2 pneumonia/ARDS at presentation, to track the evolution of disease, to monitor lung recruitment maneuvers, to guide response to prone position, the management of extracorporeal membrane therapy, and for making decisions related to weaning the patient form ventilatory support.