Association Between Intraoperative Hyperoxia and Acute Kidney Injury After Cardiac Surgery: A Retrospective Observational Study

Abstract

Objective: Optimal oxygen management during cardiac surgery has not been established, and studies on the effects of perioperative hyperoxia on postoperative acute kidney injury (AKI) are scarce. The association between intraoperative hyperoxia and AKI after cardiac surgery involving cardiopulmonary bypass was evaluated for the present study.

Design: Retrospective observational study.

Setting: A tertiary teaching hospital.

Participants: Adult patients who underwent cardiac surgery with cardiopulmonary bypass from November 2006-December 2018.

Interventions: None.

Measurements and main results: The area above arterial oxygen partial pressure (PaO₂) threshold of 300 mmHg (AOT₃₀₀, mmHg × h) was used as a metric of intraoperative hyperoxia and was associated with postoperative AKI, using the logistic regression analysis. Data also were fitted using the restricted cubic spline model. Sensitivity analyses were conducted using different PaO₂ thresholds (150, 200, 250, and 350 mmHg). A total of 2,926 patients were analyzed. Intraoperative AOT₃₀₀ independently was associated with the risk of AKI (odds ratio 1.0009; 95% confidence interval 1.0002-1.0015). A PaO₂ increment of 100 mmHg above PaO₂ 300 mmHg for an hour was associated with an increased risk of AKI by 9.4% (1.0009¹⁰⁰ ≈ 1.094). In the spline model, the log-odds of AKI increased as AOT₃₀₀ increased. In the sensitivity analyses, AOT₂₅₀ and AOT₃₅₀ also significantly were associated with the risk of AKI, whereas AOT₁₅₀ and AOT₂₀₀ were not. As the PaO₂ threshold increased from 150 to 350 mmHg, the odds ratio gradually increased.

Conclusions: Intraoperative hyperoxia significantly was associated with the risk of AKI after cardiac surgery involving cardiopulmonary bypass.

Keywords: acute kidney injury; cardiac surgery; cardiopulmonary bypass; hyperoxia; oxygen.