Background

While hyperoxia has conventionally been the standard during cardiopulmonary bypass (CPB) to prevent hypoxemia, recent concerns regarding oxygen-induced oxidative stress have sparked debate over whether a normoxic strategy provides a safer clinical alternative.

Methods

A comprehensive search of PubMed, Web of Science, CENTRAL, and Scopus was conducted to identify randomized controlled trials (RCTs) through December 2025. Primary outcomes included short-term and long-term mortality, and acute kidney injury (AKI). Secondary outcomes included assessment of clinical complications and healthcare resource utilization. Risk ratios (RR) and mean differences (MD) were pooled using a random-effects model.

Results

Twelve RCTs involving 2,732 patients were included. The analysis found no significant difference between hyperoxia and normoxia in short-term mortality (RR: 1.23, 95% CI [0.60, 2.54]; p = 0.57), long-term mortality (RR: 1.10, 95% CI [0.84, 1.43]; p = 0.48), or the incidence of AKI (RR: 0.94, 95% CI [0.82, 1.07]; p = 0.32). Similarly, no significant differences were observed in secondary clinical outcomes, including myocardial infarction, stroke, arrhythmia, or surgical site infections. Hospital resource utilization was comparable, with no significant differences in mechanical ventilation duration (p = 0.06), ICU stay (p = 0.32), or length of hospital stay (p = 0.08).

Conclusion

This meta-analysis detected no statistically significant differences between hyperoxic and normoxic strategies during CPB regarding mortality, clinical outcomes, or hospital resource utilization. Still, the current evidence remains uncertain, warranting further research.