Lung Ultrasound May Support Diagnosis and Monitoring of COVID-19 Pneumonia

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease (COVID-19) is characterized by severe pneumonia and/or acute respiratory distress syndrome in about 20% of infected patients. Computed tomography (CT) is the routine imaging technique for diagnosis and monitoring of COVID-19 pneumonia. Chest CT has high sensitivity for diagnosis of COVID-19, but is not universally available, requires an infected or unstable patient to be moved to the radiology unit with potential exposure of several people, necessitates proper sanification of the CT room after use and is underutilized in children and pregnant women because of concerns over radiation exposure. The increasing frequency of confirmed COVID-19 cases is striking, and new sensitive diagnostic tools are needed to guide clinical practice. Lung ultrasound (LUS) is an emerging non-invasive bedside technique that is used to diagnose interstitial lung syndrome through evaluation and quantitation of the number of B-lines, pleural irregularities and nodules or consolidations. In patients with COVID-19 pneumonia, LUS reveals a typical pattern of diffuse interstitial lung syndrome, characterized by multiple or confluent bilateral B-lines with spared areas, thickening of the pleural line with pleural line irregularity and peripheral consolidations. LUS has been found to be a promising tool for the diagnosis of COVID-19 pneumonia, and LUS findings correlate fairly with those of chest CT scan. Compared with CT, LUS has several other advantages, such as lack of exposure to radiation, bedside repeatability during follow-up, low cost and easier application in low-resource settings. Consequently, LUS may decrease utilization of conventional diagnostic imaging resources (CT scan and chest X-ray). LUS may help in early diagnosis, therapeutic decisions and follow-up monitoring of COVID-19 pneumonia, particularly in the critical care setting and in pregnant women, children and patients in areas with high rates of community transmission.

Keywords: Acute respiratory disease syndrome; B-Lines; COVID-19; Interstitial syndrome; Lung ultrasound; Pneumonia.

Fig. 1

(a) A-Lines: Lines horizontal to the pleura. (b–e). B-Lines: Linear vertical artifacts that arise from pleural lines (a) with different B-line shapes, for example, a single cone-shaped line (b), a single thin line (c), a single thick line (d) and a subpleural consolidation without air bronchogram (e).

Fig. 2

Different scoring systems used to quantify the extent and characterize the different patterns of lung involvement.

Fig. 3

Ultrasonographic features of normal lung and COVID-19 pneumonia. (a) Normal sonographic lung appearance. Pleural line (hyper-echoic horizontal line, green arrowhead) and multiple horizontal reverberations of the pleural line (A-lines). (b) Severe interstitial pneumonia and acute respiratory distress syndrome sonographic appearance. Green arrowhead indicates irregular pleural line; vertical lines indicate multiple blurred B-lines.