I-ASV in Cardiac Surgery

Inclusion Criteria: * 1\. aged \> 18 years of age; * 2\. scheduled for elective cardiac surgery; and * 3\. expected to receive postoperative ventilation in the ICU for \> 2 hours. Exclusion Criteria: 1. any emergency or semi-elective surgery (precluding informed written consent); 2. any surgery other than CABG, valve replacement or repair, or a combination (i.e., patients planned for surgery for congenital heart disease, or scheduled for heart transplantation are excluded); 3. enrolled in another interventional trail; 4. no written informed consent obtained; 5. history of recent pneumectomy or lobectomy; 6. history of COPD with oxygen at home; 7. body mass index \> 35; 8. preoperative forced expiratory volume in the first second (FeV1)/forced vital capacity (VC) \< 50% (if available); 9. preoperative arterial oxygen partial pressure (PaO2) \< 60 mm Hg (at room air); 10. preoperative arterial carbon dioxide partial pressure (PaCO2) \> 50 mm Hg; 11. preoperative left ventricular ejection fraction \< 30% (if available); 12. preoperative systolic pulmonary artery pressure \> 60 mm Hg (if available); 13. preoperative left ventricular mechanical support, e.g., Impella®; or 14. preoperative use of veno-venous or veno-arterial extracorporeal support At the end of surgery, patients are additionally excluded if a patient: 15. cannot be weaned from the extracorporeal support; or 16. unexpectedly needs implementation of an assist device