An interventional study of Oxygen Reserve Index (ORi)-guided oxygen titration in One Lung Ventilation in Thoracic Surgery, sponsored by Gazi University. Completed at 1 site in Turkey (Türkiye). Open to participants aged 18 Years to 85 Years. Per ClinicalTrials.gov, last updated 2026-01-22.
Sponsored by Gazi University · Not applicable, Interventional, and Treatment
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.
One-lung ventilation is an essential component of thoracic anesthesia but poses significant challenges in maintaining adequate oxygenation. In clinical practice, high FiO₂ levels are often applied to prevent hypoxemia; however, prolonged exposure to hyperoxia has been associated with increased oxidative stress, inflammatory responses, and potential tissue damage. Despite growing awareness of oxygen toxicity, optimal intraoperative oxygen titration strategies during OLV remain poorly defined.
The Oxygen Reserve Index is derived from multiwavelength pulse oximetry and provides continuous, noninvasive information on moderate hyperoxia (corresponding to arterial oxygen tensions above normoxia but below severe hyperoxia). ORi monitoring may enable anesthesiologists to titrate FiO₂ more precisely, thereby avoiding unnecessary oxygen exposure while maintaining adequate oxygenation.
In this prospective, randomized clinical trial, adult patients scheduled for elective thoracic surgery requiring OLV are allocated to either an ORi-monitored group or a control group. In the ORi group, FiO₂ is adjusted intraoperatively according to predefined ORi thresholds, whereas in the control group FiO₂ is managed according to standard clinical practice based on pulse oximetry. Blood and tracheal aspirate samples are collected preoperatively and at predefined postoperative time points to measure interleukin-6, superoxide dismutase, and malondialdehyde levels as markers of inflammation and oxidative stress. Postoperative pulmonary complications and surgical site infections are recorded during intensive care unit and ward follow-up.
This study aims to determine whether ORi-guided oxygen titration during OLV can safely reduce intraoperative oxygen exposure and to clarify its impact on biochemical markers of oxidative stress and clinical outcomes such as postoperative pulmonary complications and surgical site infection.
115 studies on the registry are indexed under Hyperoxia; 13 are open to participants now.
This study's enrollment of 60 is above the median of 48 across 82 interventional studies indexed under Hyperoxia.
Browse Hyperoxia studies →Gazi University is the lead sponsor of 551 studies on the registry; 102 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
LVEF (left ventricular ejection fraction)
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
In this group, intraoperative FiO₂ was titrated according to predefined Oxygen Reserve Index (ORi) thresholds during one-lung ventilation and all intraoperative period, with the aim of maintaining adequate oxygenation while avoiding unnecessary hyperoxia.
Device: Oxygen Reserve Index (ORi)-guided oxygen titration
In this group, intraoperative FiO₂ was adjusted based solely on pulse oximetry (SpO₂) monitoring, without the use of Oxygen Reserve Index (ORi) guidance.
FiO₂ adjusted intraoperatively according to predefined ORi thresholds during thoracic surgery and one lung ventilation period.
Mean intraoperative FiO₂
The primary outcome is the mean fraction of inspired oxygen (FiO₂) administered during one-lung ventilation and throughout the entire duration of surgery, recorded continuously intraoperatively and compared between the ORi-guided and conventional oxygen management groups.
Time frame: From anesthesia induction to the extubation
Oxidative stress biomarkers (IL-6, SOD, MDA)
Changes in serum and tracheal aspirate levels of interleukin-6, superoxide dismutase, and malondialdehyde assessed at four time points. Serum biomarker levels are measured at anesthesia induction and at the 12th and 24th postoperative hours, while tracheal aspirate biomarker levels are measured at extubation. Results are compared between the ORi and Non-ORİ groups.
Time frame: Anesthesia induction, extubation, postoperative 12th hour, postoperative 24th hour
Postoperative pulmonary complications
Incidence of postoperative pulmonary complications, including prolonged drainage, hemothorax, bronchopleural fistula, reintubation, atelectasis, bronchopneumonia, and acute respiratory distress syndrome, assessed during intensive care unit and ward follow-up.
Time frame: up to 2 weeks
Surgical site infections
Incidence of surgical site infections recorded during postoperative hospital stay.
Time frame: up to 2 weeks
Plan to share: No — The data generated during this study may be made available for use in future meta-analyses upon reasonable request to the corresponding author.
Ran from Aug 2022 to primary completion in Jul 2023, 11 months.
Of 37 non-industry interventional studies with no phase under Hyperoxia, half reached primary completion within 16 months of starting (the median), counting those still running; a quarter within 5 and three quarters within 33. This study's 11 months is below that.
Counting every sponsor, half of 39 studies reached it within 12 months; a quarter within 5 and three quarters within 33.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in Aug 2022. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.