PROtective Ventilation With FLOW-Controlled Ventilation

"In the FCV group, intraoperative ventilation will be provided with the EVONE (IES Ventinova Medical).PEEP and Ppeak are titrated guided by dynamic compliance, as follows: Starting from a default setting of 5 cmH2O of PEEP and 15 cmH2O of Ppeak, PEEP and Ppeak are equally increased by 1 cmH2O steps and the PEEP value with the highest VT and thus highest dynamic compliance is defined as best PEEP. Subsequently, Ppeak is stepwise (+1 cmH2O) increased until there is no further over-proportional increase in tidal volume (VT) (i.e. measured VT \> expected VT according to measured dynamic compliance), defined as best driving pressure. No recruitment maneuvers are carried out during FCV. With the I:E ratio set to 1:1, flow is adjusted to establish normocapnia (target etCO2 4.5 to 5.8 kPa). FiO2 is adjusted to maintain oxygen saturation (SpO2) \> 92%."

In the PCV group, intraoperative ventilation will be provided by a standard anesthesia ventilator in use in the respective participating centers. Patients will be ventilated in PCV mode, at the lowest inspired oxygen fraction (FiO2), to maintain oxygen saturation (SpO2) \> 92%. It is left to the discretion of the attending anesthesiologist to use a higher fraction of FiO2. Inspiratory to expiratory ratio is set at 1:1 to 1:2, respiratory rate will be adjusted to target normocapnia (target etCO2 4.5 to 5.8 kPa. VT will be set at 7 to 9 ml/kg predicted body weight (PBW). The PBW is calculated according to a predefined formula: 50 + 0.91 x (centimeters of height - 152.4) for males and 45.5 + 0.91 x (centimeters of height - 152.4) for females. Ventilation starts with 5 cm H2O PEEP, and can be increased to 10 cm H2O PEEP.