The Intraop Ox trial will enroll adult patients undergoing surgery with tracheal intubation. Participating hospitals will be randomly assigned (as a unit) to administer one of three oxygenation strategies during maintenance anesthesia (lower FiO₂ \[0.21-0.40\], intermediate FiO₂ \[0.40-0.80\], or higher \[FiO₂ 0.80-1.00\] each period (month). The primary outcome is a composite of organ injury (acute kidney injury, myocardial injury, lung injury, stroke) or death within 30 days. Secondary outcome is 30-day mortality. Exploratory outcomes are individual components of the composite primary endpoint, surgical site infection, length of stay, and hypoxemia. The study is conducted under a waiver of informed consent due to minimal incremental risk of participating and impracticability of obtaining consent in this cluster-randomized design.
