Inclusion Criteria:  Patients were considered eligible if they met the Berlin definition criteria for ARDS and intubated due to increased work of breathing and/or worsening hypoxemia. All patients had a positive Covid-19 real time Polymerase Chain Reaction test  Exclusion Criteria:  Exclusion criteria were; age < 18 years, ARDS resulting from other risk factors, presence of chest drainage tubes, tracheostomy, pneumomediastinum, hemodynamic instability (systolic blood pressure < 100 mmHg, lactate > 2 mmol/l, or an increase in lactate concentrations for 20% in two consecutive blood gas analysis within 2 hours interval) and suspicion or confirmed pulmonary emboli.