Lung Ultrasound Findings Are Associated with Mortality and Need for Intensive Care Admission in COVID-19 Patients Evaluated in the Emergency Department

Abstract

Lung ultrasound (LUS) has recently been advocated as an accurate tool to diagnose coronavirus disease 2019 (COVID-19) pneumonia. However, reports on its use are based mainly on hypothesis studies, case reports or small retrospective case series, while the prognostic role of LUS in COVID-19 patients has not yet been established. We conducted a prospective study aimed at assessing the ability of LUS to predict mortality and intensive care unit admission of COVID-19 patients evaluated in a tertiary level emergency department. Patients in our sample had a median of 6 lung areas with pathologic findings (inter-quartile range [IQR]: 6, range: 0-14), defined as a score different from 0. The median rate of lung areas involved was 71% (IQR: 64%, range: 0-100), while the median average score was 1.14 (IQR: 0.93, range: 0-3). A higher rate of pathologic lung areas and a higher average score were significantly associated with death, with an estimated difference of 40.5% (95% confidence interval [CI]: 4%-68%, p = 0.01) and of 0.47 (95% CI: 0.06-0.93, p = 0.02), respectively. Similarly, the same parameters were associated with a significantly higher risk of intensive care unit admission with estimated differences of 29% (95% CI: 8%-50%, p = 0.008) and 0.47 (95% CI: 0.05-0.93, p = 0.02), respectively. Our study indicates that LUS is able to detect COVID-19 pneumonia and to predict, during the first evaluation in the emergency department, patients at risk for intensive care unit admission and death.

Keywords: COVID-19; Emergency medicine; Lung ultrasound; Pneumonia; SARS-CoV-2.

Fig. 1

Representation of lung ultrasound score for COVID-19 patients according to Soldati et al. (2020c). (a–d) Localization of the 14 areas evaluated with lung ultrasound. (e) Lung ultrasound score 0 (normal pattern), with clear A-lines (horizontal artifacts, white arrows). (f) Lung ultrasound score 1, with pleural line irregularity (white, thick arrow) and a single vertical artifact (B-line, white arrow). (g) Lung ultrasound score 2, with pleural line irregularity (white, thick arrow) and multiple but not confluent vertical artifacts (B-lines, white arrow). (h) Lung ultrasound score 3, with a subpleural consolidation (black arrow) and a large area of white lung (double-head black arrow).

Fig. 2

Study flowchart illustrating patient selection. ED = emergency department; LUS = lung ultrasound.

Fig. 3

Representation of the different scores at lung ultrasound in the whole population (a) and by the lung area evaluated (a).

Fig. 4

Boxplot illustrating the distribution of percentages of pathologic areas with respect to the (a) need for intensive care unit (ICU) admission, (b) need for invasive ventilation and (c) outcome of index hospitalization (death, discharge) (c).

Fig. 5

Boxplot illustrating the distribution of average lung ultrasound score areas according to the need for intensive care unit (ICU) admission (a), the need for invasive ventilation (b) and the outcome of the index hospitalization (death, discharged) (c).

Fig. 6

Boxplot showing the distribution of absolute number of pathologic areas according to the need for intensive care unit (ICU) admission (a), the need for invasive ventilation (b) and the outcome of the index hospitalization (death, discharged) (c).

Fig. 7

Cohen's κ values for the concordance between lung ultrasound and chest X-ray using different cutoff values of the average ultrasound score (a) and the percentage of pathologic areas at lung ultrasound (b) needed to define a patient has having interstitial pneumonia. For each point, the x-axis represents the cutoff, and the y-axis represents the corresponding κ value for concordance with chest X-ray.