T1 and T2
apnea
Patients were then first connected either to OPatients were ventilated for ≥ 10 min with OT2 was defined as the time point at the end of the first apnea phase (when the primary or the safety endpoint was reached). Ventilation was performed with the ventilator settings used at T0 to allow the patient to return to its steady state for ≥ 2 min. Then the crossover ventilation was initiated for 10 min.