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NCT Number: NCT07359833

Oxygen Reserve Index Guided FiO₂ Titration in One-Lung Ventilation

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.

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Key information

Conditions

One Lung Ventilation in Thoracic Surgery Hyperoxia Pathological Conditions, Signs and Symptoms Signs and Symptoms Signs and Symptoms, Respiratory

Age range

18 year–85 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Gazi University

Ankara, 06560, Turkey (Türkiye)

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Patients age between 18-85 years Elective case Thoracic surgeries performed with one-lung ventilation using a double-lumen endotracheal tube Left ventricule ejection fraction(LVEF)>45%

Exclusion criteria

  • heart failure (LVEF) < 45% severe valvular disease admission as an emergency case history of prior lung resection presence of peripheral arterial disease.

Treatment and study plan

Oxygen Reserve Index (ORi)-guided oxygen titration

Device

FiO₂ adjusted intraoperatively according to predefined ORi thresholds during thoracic surgery and one lung ventilation period.

Primary outcomes

  1. Mean intraoperative FiO₂

    Time frame: From anesthesia induction to the extubation

    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.

Secondary outcomes

  1. Oxidative stress biomarkers (IL-6, SOD, MDA)

    Time frame: Anesthesia induction, extubation, postoperative 12th hour, postoperative 24th hour

    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.

  2. Postoperative pulmonary complications

    Time frame: up to 2 weeks

    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.

  3. Surgical site infections

    Time frame: up to 2 weeks

    Incidence of surgical site infections recorded during postoperative hospital stay.

Sponsors and collaborators

Lead sponsor

Gazi University

Other

Registry information

Official study title

Effects of FiO2 Adjustment on Hyperoxia Biomarkers and Postoperative Complications Using Oxygen Reserve Index During One-lung Ventilation

Important dates

Study start
2022
Primary completion
2023
Study completion
2023
First posted
Jan 22, 2026
Registry last updated
Jan 22, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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