During conventional lung protective ventilation, the attending physician sets the ventilator according to the local ventilation protocol. The fraction of inspired oxygen (FiO2) is adjusted to maintain an oxygen saturation of 92 to 96% and/or a PaO2 of > 8 kPa. The respiratory rate is adjusted to maintain a blood pH of 7.25 to 7.45. The lowest level of positive end-expiratory pressure (PEEP) is 5 cm H2O; allowed PEEP-FiO2 are in concordance with the ARDS network recommendations;5 these combinations are based on two large RCTs in ARDS patients, and is standard practice in our unit.