This is an international multicenter cohort study on data collected between March and April 2020. The first available lung ultrasound examination that used a 12-regions approach was used to calculate the global LUS score.

Patients are included if they fulfilled the following criteria: 1) admitted to one of the participating ICU; 2) for invasive ventilation; 3) for respiratory failure due to confirmed COVID-19; and 4) having had a LUS examination performed within the first week of start of invasive ventilation.

The primary and secondary outcomes were liberation from invasive ventilation and mortality.

Demographic, clinical and outcome variables will be presented as percentages for categorical variables and as medians with interquartile ranges (IQR) for continuous variables.

Receiver operating characteristics (ROC) analysis will be used to derive the prognostic discriminatory performance of global LUS score in determining succesful extubation and mortality at day 28. The Youden index will be used to derive the optimal cut-off. The association of global LUS with unfavourable outcomes are analyzed with Cox proportional hazard analysis (for successful extubation and alive at day 28), logistic regression models (mortality at day 28). Hazard ratio or odds ratio with 95% confidence intervals were calculated for each outcome.