Science, Medicine, and the Anesthesiologist

Liberal administration of oxygen (hyperoxia) is commonly used intraoperatively ostensibly to enhance patient safety, particularly during cardiac surgery, despite potential adverse effects on perioperative organ function related to oxidative stress. This assessor- and participant-blinded clinical trial at a single tertiary U.S. center randomized stable adult patients undergoing elective open cardiac surgery with cardiopulmonary bypass to either hyperoxia (1.00 fraction of inspired oxygen [Fio₂]) or normoxia (minimum Fio₂ to maintain oxygen saturation 95 to 97%) (N = 100 in each group following exclusions; median [interquartile range] age, 66 [59 to 72] yr; 70% male). The primary mechanistic endpoint was oxidative damage (the sum of plasma concentrations of F2- isoprostanes and isofurans collected during and after surgery), and the primary clinical endpoint was change in serum creatinine concentration from baseline to postoperative day 2. Secondary outcomes included kidney, myocardial, and brain and respiratory injury markers and safety outcomes; 1-yr follow-up was performed. The primary mechanistic outcome was significantly higher in the hyperoxia group by 9.2 pg/ml (95% CI, 1.0 to 17.4; P = 0.03), whereas there was no difference in the clinical endpoint (median difference, 0.03; 95% CI, −0.04 to 0.10; P = 0.45). There were no differences in secondary outcomes and at 1 yr.