Daily. From day 1 (i.e., within 24 hours from enrollment) to day 28 or death or discharge from the ICU, the following data will be collected every day between 6:00 and 10:00 in the morning: switch from the allocated treatment to the other study arm for ≥24 hours, reason for switch from the allocated treatment, adverse events (i.e., hemodynamic instability with hypotension with SBP <90 mmHg despite vasoactive drugs; arrhythmias with heart rate <40 or >140 bpm; radiographic evidence of barotrauma with pneumothorax, pneumomediastinum, pneumatocoele, or subcutaneous emphysema), arterial SpO2, arterial and central venous blood gas analyses, numbers of quadrants involved on standard chest X-ray, ventilation settings and pattern (i.e., Sigh pressure level, Sigh tidal volume, PSV level, PSV tidal volume, respiratory rate, PEEP, FiO2, minute ventilation, P0.1, mean airway pressure), switch to controlled ventilation for ≥24 hours, reason for switch to controlled ventilation, use of rescue treatments (i.e., use of PEEP ≥15 cmH2O, prone positioning, inhaled nitric oxide, extracorporeal membrane oxygenation), dosage of sedative agents, RASS value, tracheostomy, patient's comfort through visual analog scale, heart rate, arterial blood pressure, central venous pressure, dosage of vaso-active drugs, cumulative fluid balance, SOFA score, SBT failure in the previous 24 hours, reason for SBT failure, time since extubation or separation from mechanical ventilation, time since re-intubation, reason for re-intubation.