Feasibility of using point-of-care lung ultrasound for early triage of COVID-19 patients in the emergency room

Abstract

Purpose: Diagnostic value of point-of-care lung ultrasound (POCUS) in detection of coronavirus disease (COVID-19) in an emergency setting is currently unclear. In this study, we aimed to compare diagnostic performance, in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy, of POCUS lung, chest CT, and RT-PCR for clinically suspected COVID-19 infections in patients submitting to the emergency room (ER).

Material and methods: This retrospective study enrolled 93 patients with a suspected COVID-19 infection, admitted to the ER between March 28th and April 20th, 2020. Test subjects showed one or more symptoms of an acute respiratory infection, for which consequent COVID-19 testing was achieved using POCUS lung, chest CT, and RT-PCR. CT images were analyzed by 2 radiologists blinded to RT-PCR results. POCUS lung was performed by three emergency medical doctors, and reports were analyzed by the researcher, blinded to clinical information, US imaging, CT, and RT-PCR test results.

Results: Compared with RT-PCR, POCUS lung demonstrated outstanding sensitivity and NPV (93.3% and 94.1% respectively) while showing poor values for specificity, PPV, and accuracy (21.3%, 19.2%, and 33.3% respectively). In contrast, similar inquiries using chest CT as index test, excellent sensitivity, specificity, NPV, and accuracy (80.0%, 86.7%, 95.6%, and 85.6%, respectively) were reported, beside a moderate value for PPV (54.5%).

Conclusion: POCUS may provide early ER triage with a useful, rapid, low-threshold, and safe screening tool in evaluating possible COVID-19 infections. Due to limited specificity, suggestive POCUS lung findings should be confirmed with RT-PCR or chest CT.

Keywords: COVID-19; Emergency room; Negative predictive value; POCUS lung; Sensitivity.

Fig. 1

Study flowchart for POCUS lung as index test. RT-PCR real-time polymerase chain reaction, chest CT chest computed tomography, POCUS point-of-care ultrasound

Fig. 2

Study flowchart for chest CT as index test. RT-PCR real-time polymerase chain reaction, chest CT chest computed tomography, POCUS point-of-care ultrasound

Fig. 3

Example POCUS lung and CT images in one RT-PCR-confirmed COVID-19-positive patient. Images were obtained from a 66-year-old woman presenting in the ER with dyspnea, coughing, and fever for 8 days. POCUS lung image of the right PLAPS point (a) shows the pleural line (black arrow) as well as a confluent pattern of B-lines (white arrow). Axial CT (b) shows typical early COVID-19 findings with bilateral subpleural areas of ground-glass opacities (white arrows).