To study the features of lung ultrasound imaging of severe coronavirus disease 2019 (COVID-19), and provide reference for clinical diagnosis and treatment.

Twenty-nine patients with severe COVID-19 admitted to ICU of our hospital were enrolled, 15 cases with severe and 14 cases with critical COVID-19. Pulmonary ultrasound examination and scoring were performed within 24 hours after admission to ICU by one specialized observer, the clinical information including gender, age, oxygenation index (OI) and disease course of all patients were collected by another observer, and clinical pulmonary infection score (CPIS) was calculated with body temperature, OI, chest X-ray or CT, airway secretions, and white blood cell count.

29 patients'clinical information include: male 23 cases (79.3%), age (62.59±11.91) years, LUS (19.28±4.96) points, OI (184.24±66.18) mmHg, CPIS 4 (3-4) points), and disease course (12.48±5.34) days. LUS was negatively correlated with OI (r=-0.742, P=0.000) and positively correlated with CPIS (r=0.516, P=0.000). LUS and CPIS of critically ill patients were significantly higher than those of severe patients (P<0.05), and OI was significantly lower (P<0.05). There were no statistically significant differences in gender, age and disease course between the two groups (P>0.05). Among the 348 pulmonary ultrasound examination regions, the major manifestations were B2 signs. Compared with the severe patients, critically ill patientshad less N signs (9.5% vs 23.3%, P<0.01), more C signs (17.3% vs 4.4%, P<0.01), and more proportion of lesion areas was (90.5% vs 76.7%, P<0.01).The pulmonary lesion areas in the anterior, lateral and posterior regions were 63.8%, 87.9% and 98.3%, showing statistical differences (P<0.01). There was no statistical difference in the distribution of ultrasonic signs and lesion areas between the left lung and the right one (P>0.05).

Pulmonary ultrasound can be used to assess pulmonary lesions for their characteristics and scopesin patients with severe COVID-19 at the point of care and can provide an important reference for the diagnosis and treatment of severe COVID-19 patients.