The role of lung ultrasound as a frontline diagnostic tool in the era of COVID-19 outbreak

Abstract

The diffusion of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) worldwide prompted the World Health Organization to declare the status of pandemic. The molecular diagnosis of SARS-CoV-2 infection is based on the detection of viral RNA on different biological specimens. Unfortunately, the test may require several hours to be performed. In the present study, we evaluated the diagnostic accuracy of lung point-of-care ultrasound (POCUS) for SARS-CoV-2 pneumonia in a cohort of symptomatic patients admitted to one emergency department (ED) in a high-prevalence setting. This retrospective study enrolled all patients who visited one ED with suspected respiratory infection in March 2020. All the patients were tested (usually twice if the first was negative) for SARS-CoV-2 on ED admission. The reference standard was considered positive if at least one specimen was positive. If all the specimens tested negative, the reference was considered negative. Diagnostic accuracy was evaluated using sensitivity, specificity, and positive and negative predictive value. Of the 444 symptomatic patients who were admitted to the ED in the study period, the result of the lung POCUS test was available for 384 (86.5%). The sensitivity of the test was 92.0% (95% CI 88.2-94.9%), and the specificity was 64.9% (95% CI 54.6-74.4%). We observed a prevalence of SARS-CoV-2 infection of 74.7%. In this setting, the positive and negative predicted values were 88.6% (95% CI 84.4-92.0) and 73.3% (95% CI 62.6-82.2%), respectively. Lung POCUS is a sensitive first-line screening tool for ED patients presenting with symptoms suggestive of SARS-CoV-2 infection.

Keywords: COVID-19; Diagnostic test; Point-of-care ultrasound; SARS-CoV-2; Sensitivity; Specificity.

Fig. 1

Flow chart describing the patient selection and classification according to the POCUS test and reference standard