Point-of-care lung ultrasound in the assessment of suspected COVID-19: a retrospective service evaluation with a severity score

Abstract

Introduction: Point-of-care lung ultrasound (POCUS) has been advocated as a tool to assess the severity of COVID19 and thereby aid risk stratification. Methods: We conducted a retrospective service evaluation between the 3rd March and the 5th May 2020 to describe and characterise the use of POCUS within an acute care pathway designed specifically for the assessment of suspected or confirmed COVID-19. A novel POCUS severity scale was formulated by assessing pleural and interstitial abnormalities within six anatomical zones (three for each lung). An aggregated score was calculated for each patient and evaluated as a marker of disease severity using standard metrics of discriminatory performance. Results: POCUS was performed in the assessment of 100 patients presenting with suspected COVID-19. POCUS was consistent with COVID-19 infection in 92% (n = 92) of the patients assessed. Severity, as assessed by POCUS, showed good discriminatory performance to predict all-cause inpatient mortality, death or critical care admission, and escalated oxygen requirements (AUC .80, .80, 82). The risk of all-cause mortality in patients with scores in lowest quartile was 2.5% (95%CI 0.12- 12.95) compared with 42.9% (95CI 15.8 – 75.0%) in the highest quartile. POCUS assessed severity correlated with length of stay and duration of supplemental oxygen therapy. Conclusion: A simple aggregated score formed by the summating the degree of pleural and interstitial change within six anatomical lung zones showed good discriminatory performance in predicting a range of adverse outcomes in patients with suspected COVID-19.