Oxygen Reserve Index Guided FiO₂ Titration in One-Lung Ventilation

January 21, 2026 updated by: Bugra AYKENAR, Gazi University

Effects of FiO2 Adjustment on Hyperoxia Biomarkers and Postoperative Complications Using Oxygen Reserve Index During 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.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

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.

Study Type

Interventional

Enrollment (Actual)

60

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

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.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: ORi group.
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
FiO₂ adjusted intraoperatively according to predefined ORi thresholds during thoracic surgery and one lung ventilation period.
No Intervention: Non-ORi group
In this group, intraoperative FiO₂ was adjusted based solely on pulse oximetry (SpO₂) monitoring, without the use of Oxygen Reserve Index (ORi) guidance.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
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.
From anesthesia induction to the extubation

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
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.
Anesthesia induction, extubation, postoperative 12th hour, postoperative 24th hour
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.
up to 2 weeks
Surgical site infections
Time Frame: up to 2 weeks
Incidence of surgical site infections recorded during postoperative hospital stay.
up to 2 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Gazi University

Investigators

  • Principal Investigator: Buğra Aykenar, Gazi University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

August 5, 2022

Primary Completion (Actual)

July 15, 2023

Study Completion (Actual)

August 30, 2023

Study Registration Dates

First Submitted

January 17, 2026

First Submitted That Met QC Criteria

January 21, 2026

First Posted (Actual)

January 22, 2026

Study Record Updates

Last Update Posted (Actual)

January 22, 2026

Last Update Submitted That Met QC Criteria

January 21, 2026

Last Verified

August 1, 2022

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • GaziU-AR-BA-01

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

The data generated during this study may be made available for use in future meta-analyses upon reasonable request to the corresponding author.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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