inclusion criteria: - patient above 18 year-old. - diagnosis of severe ards due to covid-19 under invasive mechanical ventilation, - meet criteria for pp: pao2/fio2 < 150 millimeters of mercury column (mmhg), peep ≥ 5 centimeters of water (cmh2o), fio2 ≥ 60.

inclusion criteria: - patient above 18 year-old. - diagnosis of severe ards due to covid-19 under invasive mechanical ventilation, - meet criteria for pp: pao2/fio2 < 150 millimeters of mercury column (mmhg), peep ≥ 5 centimeters of water (cmh2o), fio2 ≥ 60.