Table 1 Time schedule for enrolment, allocation, interventions and assessments in the main and ancillary studies. Calculations for the Assess Respiratory Risk in Surgical Patients in Catalonia (ARISCAT) Score [34] can only be completed when SpO2 is measured at the time of patient arrival in the induction room. The EuroSCORE II [35] is recalculated after CPB based on the actual intraoperative cardiac surgical interventions. Additional arterial BGAs are conducted simultaneously to the EIT recordings on CPAP and pressure support ventilation during weaning as well as 30–60 min after extubation. Close-out of participants is after the second phone survey 6 months after the cardiac surgery procedure. The first phone survey is conducted one month postoperatively. Post-allocation time points: Base, patient breathing spontaneously before induction of anesthesia; T−2, after group-specific individualization of ventilation and before skin incision; T−1, 15 min after thoracotomy; T0, after CPB termination and transfusion stop from the extracorporeal circulation; T1–24, appropriate hour after CPB end. BGA, blood gas analysis; BNP, brain natriuretic peptide; CK-MB, creatine kinase MB; CPAP, continuous positive airway pressure ventilation during weaning; PEEP, positive end-expiratory pressure; PEPCs, postoperative extra-pulmonary complications; POD, postoperative day; PPCs, postoperative pulmonary complications
