Hyperoxia and Antioxidants During Major Non-cardiac Surgery and Risk of Cardiovascular Complications, a Blinded 2x2 Factorial Randomised Clinical Trial

Adult patients with risk factors for developing postoperative cardiac complications will be enrolled in the study. The patients will be randomised to receiving antioxidants or placebo perioperatively and 30% or 80% inspiratory oxygen concentration during anaesthesia and 2 hours postoperatively. The primary outcome is MINS (myocardial injury after non-cardiac surgery). The antioxidants are ascorbic acid (vitamin C) 3 grams intravenously preoperatively and N-acetylcysteine 100 milligrams/kilogram body weight intravenous infusion for 4 hours, starting at the same time as anaesthesia.

The study is a long-term follow-up study of the risk of mortality, MI and readmissions performed at 1 year after inclusion of the last patient. Two other follow-up studies are planned: One investigation of ischaemic troponin elevations defined as peak troponin levels above the internationally defined thresholds without extracardiac causes; another investigating the intervention effects in the subgroup of patients undergoing vascular surgery with specific emphasis on episodes of intraoperative hypotension within the following thresholds: MAP below 70 mmHg, 65 mmHg, 60 mmHg and 55 mmHg.