Hyperoxia vs Normoxia During Cardiopulmonary Bypass

This monocentric randomized controlled pilot trial enrolled adult patients undergoing elective cardiac surgery requiring CPB. Participants were randomized (1:1) to receive either normoxic (PaO₂ 70-150 mmHg) or hyperoxic (PaO₂ >300 mmHg) oxygenation strategies intraoperatively.

The study evaluates postoperative renal function using eGFR, NGAL, renal replacement therapy, and KDIGO classification. Secondary outcomes include IL-6 levels, arrhythmias, mechanical circulatory support, surgical complications, ventilation duration, ICU/hospital stay, and 28-day mortality.

• Hyperoxia group (Other): After endotracheal intubation, FiO₂ was maintained at 0.8 and subsequently adjusted to achieve PaO₂ above 300 mmHg. During CPB, air and oxygen flows through the oxygenator were titrated to maintain a target PaO₂ greater than 300 mmHg.
• Normoxia group (control) (Other): After endotracheal intubation, FiO₂ was initially set to 0.3 and subsequently adjusted to maintain PaO₂ between 70 and 150 mmHg. During CPB, air and oxygen flows through the oxygenator were titrated to maintain a target PaO₂ between 70 and 150 mmHg.

Primary outcomes

• Number of of kidney failure in adult patients undergoing to elective cardiac surgery required CPB [At 24 hours after surgery]: The renal outcomes were evaluated 24 hours after surgery, on the first postoperative day. The failure was defined according to KDIGO criteria and included estimated glomerular filtration rate (eGFR), serum Neutrophil Gelatinase-Associated Lipocalin (NGAL), and the need for postoperative renal replacement therapy.

Secondary outcomes

• Number of patients with NGAL > 50ng/ml (index of acute kidney injury) [At 24 hours after surgery]: Serum NGAL was measured on blood sample and if NGAL: < 50 ng/mL → normal renal function 50-150 ng/mL → possible early injury 150-200 ng/mL → suggestive of AKI 400-500 ng/mL → likely AKI / moderate to severe AKI
• Number of renal replacement therapy after surgey [Within 24 hours postoperatively]: Requirement for CRRT
• Number of patients affected by postoperative arrhythmias [within 28 days after randomization]: Postoperative arrhythmias were defined according to AHA criteria
• Number of patients needing extracorporeal membrane support [within 28 days after randomization]: Mechanical circulatory support requirement was defined as veno-venous support, veno-arterial support
• Number of patients experienced surgical complications [within 28 days after randomization]: Surgical complications were defined according to Clavien-Dindo scale
• Number of patients needing tracheostomy [within 28 days after randomization]: Tracheostomy

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* adult patients (>18 years old)
* need for elective cardiac surgery requiring CPB (i.e., isolated valve repair/replacement, coronary artery bypass grafting, or ascending aorta surgery)
* Time frame from July 1st to September 15th 2025

Exclusion Criteria:

* refusal of consent,
* pregnancy,
* previous Intensive Care Unit (ICU) admission,
* history of cardiac surgery requiring CPB,
* signs of preoperative cardiogenic shock (defined as requiring inotropic support, intra-aortic balloon pump, or other mechanical circulatory assistance),
* intraoperative need for circulatory arrest.