Inclusion Criteria:  Patients aged ≥ 60 years scheduled for elective off-pump CABG.  Exclusion Criteria:  Inability or refusal to provide consent of participation Preoperative requirement of respiratory support (intubation, CPAP or BiPAP, or high-flow oxygen (>10 L/min)) Preoperative requirement of external cardiac assist device Urgent or emergent surgery Patients expected to die within 30 days of randomization