One-lung ventilation (OLV) is routinely used during thoracic surgery to facilitate surgical exposure but is associated with an increased risk of intraoperative hypoxemia. To prevent hypoxia, high fractions of inspired oxygen (FiO₂) are commonly administered; however, excessive oxygen delivery may lead to hyperoxia and oxidative tissue injury. The Oxygen Reserve Index (ORi) is a novel, noninvasive monitoring parameter that provides real-time information on moderate hyperoxia and may allow more precise titration of FiO₂ during anesthesia.
The aim of this prospective, randomized clinical trial is to evaluate whether ORi-guided intraoperative oxygen management can reduce oxygen exposure during OLV without increasing hypoxemia and to assess its effects on oxidative stress biomarkers and postoperative outcomes. Adult patients undergoing elective thoracic surgery with OLV are randomized to receive either ORi-guided FiO₂ titration or conventional oxygen management. Oxidative stress biomarkers and postoperative pulmonary complications are compared between groups.