Lung ultrasonography features and risk stratification in 80 patients with COVID-19: a prospective observational cohort study

Background

Point-of-care lung ultrasound (LUS) is a promising and pragmatic risk stratification tool in COVID-19. This study describes and compares early LUS characteristics across of range of clinical outcomes.

Method

Prospective observational study of PCR-confirmed COVID-19 patients in the emergency department (ED) of Lausanne University Hospital. A trained physician recorded LUS images using a standardized protocol. Two experts retrospectively reviewed images blinded to patient outcome. We describe and compare early LUS findings (acquired within 24hours of presentation at the ED) between patient groups based on their outcome at 7-days after inclusion:  1) self-resolving outpatients, 2) hospitalised and 3) intubated/death. The LUS score was used to discriminate between groups.

Findings

Between March 6 and April 3 2020, we included 80 patients (18 outpatients, 41 hospitalized and 21 intubated/dead). 73 patients (91%) had abnormal LUS (72% outpatients, 95% hospitalised and 100% intubated/death; p=0.004). The proportion of involved zones was lower in outpatients compared with other groups (median  30% [IQR 0-40%], 44% [33-70%] and 70% [50-88%], p<0.001). Predominant abnormal patterns were bilateral and multifocal spread thickening of the pleura with pleural line irregularities (77%), confluent B lines (66%) and pathologic B lines (55%). Posterior inferior zones were more often affected. Median LUS score had a good level of discrimination between outpatients and others with area under the ROC of 0.80 (95% CI 0.66-0.95).

Interpretation

Systematic LUS is a reliable, cheap and easy-to-use triage tool for the early stratification of risk in COVID-19 patients presenting at emergency departments.

Funding

Leenaards Foundation