2.1. Patients

Our study was conducted in accordance with the principles of the Declaration of Helsinki. The locally appointed ethics committee has approved the research protocol, and informed consent has been obtained from all subjects.

Diagnosis of COVID‐19 was based on a positive nucleic acid test of SARE‐CoV‐2, according to the Diagnosis and Treatment Plan of Novel Coronavirus Pneumonia (trial version 7th) issued by the National Health Commission of the People's Republic of China. 7 COVID‐19 severity was assessed according to the following clinical classification: (a) light type: mild clinical symptoms, no pneumonia on imaging; (b) common type: fever, respiratory symptoms, pneumonia on imaging; (c) severe type: respiratory distress with respiratory rate ≥30/min and/or oxygen saturation ≤93% at rest and/or partial arterial pressure of oxygen/fraction of inspired oxygen ≤300 mm Hg (40 kPa); and (d) critical type: respiratory failure requiring mechanical ventilation and/or shock and/or other organ failure and admission to intensive care unit (ICU).

We performed the retrospective analysis of 81 severe and critical COVID‐19 patients who had had an ultrasonographic examination performed in the ICU of Wuhan Jinyintan Hospital from January 1, 2020 to March 5, 2020. The total number of patients on ICU during the same time was 108. At the end‐point date of March 5, 2020, the patients were divided into two groups: those who had succumbed to COVID‐19, and the surviving patients. We did not report underlying diseases, since they have been reported to be absent in 47% of deceased patients 8 .