Point-of-Care Lung Ultrasound for Detecting Severe Presentations of Coronavirus Disease 2019 in the Emergency Department: A Retrospective Analysis

Objectives: Analyze the diagnostic test characteristics of point-of-care lung ultrasound for patients suspected to have novel coronavirus disease 2019.

Design: Retrospective cohort.

Setting: Two emergency departments in Detroit, Michigan, United States, during a local coronavirus disease 2019 outbreak (March 2020 to April 2020).

Patients: Emergency department patients receiving lung ultrasound for clinical suspicion of coronavirus disease 2019 during the study period.

Interventions: None, observational analysis only.

Measurements and main results: By a reference standard of serial reverse transcriptase-polymerase chain reactions, 42 patients were coronavirus disease 2019 positive, 16 negative, and eight untested (test results lost, died prior to testing, and/or did not meet hospital guidelines for rationing of reverse transcriptase-polymerase chain reaction tests). Thirty-three percent, 44%, 38%, and 17% had mortality, ICU admission, intubation, and venous or arterial thromboembolism, respectively. Receiver operating characteristics, area under the curve, sensitivity, and specificity with 95% CIs were calculated for five lung ultrasound patterns coded by a blinded reviewer and chest radiograph. Chest radiograph had area under the curve = 0.66 (95% CI, 0.54-0.79), 74% sensitivity (95% CI, 48-93%), and 53% specificity (95% CI, 32-75%). Two lung ultrasound patterns had a statistically significant area under the curve: symmetric bilateral pulmonary edema (area under the curve, 0.57; 95% CI, 0.50-0.64), and a nondependent bilateral pulmonary edema pattern (edema in superior lung ≥ inferior lung and no pleural effusion; area under the curve, 0.73; 95% CI, 0.68-0.90). Chest radiograph plus the nondependent bilateral pulmonary edema pattern showed a statistically improved area under the curve (0.80; 95% CI, 0.68-0.90) compared to either alone, but at the ideal cutoff had sensitivity and specificity equivalent to nondependent bilateral pulmonary edema only (69% and 77%, respectively). The strongest combination of clinical, chest radiograph, and lung ultrasound factors for diagnosis was nondependent bilateral pulmonary edema pattern with temperature and oxygen saturation (area under the curve, 0.86; 95% CI, 0.76-0.94; sensitivity = 77% [58-93%]; specificity = 76% [53-94%] at the ideal cutoff), which was superior to chest radiograph alone.

Conclusions: Lung ultrasound diagnosed severe presentations of coronavirus disease 2019 with similar sensitivity to chest radiograph, CT, and reverse transcriptase-polymerase chain reaction (on first testing) and improved specificity compared to chest radiograph. Diagnostically useful lung ultrasound patterns differed from those hypothesized by previous, nonanalytical, reports (case series and expert opinion), and should be evaluated in a rigorous prospective study.