Impact of Intraoperative Oxygenation Practices on Patient Outcomes (IntraOp Ox)

September 15, 2026 updated by: Frederic T Billings IV
This multicenter, cluster-randomized, cluster-crossover clinical trial evaluates the impact of three intraoperative FiO2 (Fraction of Inspired Oxygen) oxygenation strategies-lower (FiO₂ 0.21-0.40), intermediate (FiO₂ 0.40-0.80), and higher (FiO₂ 0.80-1.00)-on postoperative organ injury and mortality in adult surgical patients. The trial aims to determine the optimal oxygenation strategy to improve perioperative outcomes.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

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.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
54000

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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 Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Michigan
      • Ann Arbor, Michigan, United States, 48109
        • Recruiting
        • University of Michigan Hospital
        • Contact:
        • Principal Investigator:
          • Christa Vaughn, MD
    • Nebraska
      • Omaha, Nebraska, United States, 68105
        • Recruiting
        • Nebraska Medical Center
        • Contact:
        • Principal Investigator:
          • Levi Zehr, MD
    • Tennessee
      • Nashville, Tennessee, United States, 37212
        • Recruiting
        • Vanderbilt University Medical Center
        • Contact:
        • Principal Investigator:
          • Meredith Kingeter, MD
    • Utah
      • Salt Lake City, Utah, United States, 84112
        • Recruiting
        • University of Utah Huntsman Cancer Institute
        • Contact:
        • Principal Investigator:
          • Caroline Ruminski, MD

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Patient located in a participating operating room
  • Planned surgery includes tracheal intubation

Exclusion Criteria:

  • Patient is known to be less than 18 years old
  • Patient is known to be pregnant
  • Patient is known to be a prisoner.
  • Patient is American Society of Anesthesiologists (ASA) classification-6 (i.e., organ donor)
  • Patient's planned surgical case includes open heart surgery, defined as surgery on the heart or ascending aorta requiring sternotomy or thoracotomy.
  • Patient's planned procedure requires prolonged apnea, bronchoscopy, airway surgery, or one-lung ventilation.
  • Patient's planned surgical case includes use of extracorporeal membrane oxygenation (ECMO).
  • Patient is known to have a history of bleomycin treatment.
  • Patient was enrolled in the trial in the prior 30 days.

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: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Lower FiO2
Other: Lower FiO2
FiO₂ 0.21-0.40 or lowest FiO₂ to maintain SpO₂ ≥ 94% during maintenance anesthesia
Experimental: Intermediate FiO2
Other: Intermediate FiO2
FiO₂ 0.40-0.80 or lowest FiO₂ to maintain SpO₂ ≥ 94% during maintenance anesthesia
Experimental: Higher FiO2
Other: Higher FiO2
FiO₂ > 0.80 to maintain SpO₂ ≥ 94% during maintenance anesthesia

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Composite of organ injury or in-hospital death within 30 days of surgery
Time Frame: 30 days post-surgery

This composite outcome measures the number of participants experiencing at least one of the following organ injuries or death within the defined study period:

  • Acute Kidney Injury (AKI), defined according to creatinine based Kidney Disease Improving Global Outcomes criteria, specifically a 0.3 mg/dL or greater increase within 48 hours or a 50% or greater increase from baseline within seven days of surgery.
  • Myocardial injury, defined as >99th percentile of normal based on site-specific troponin assay within 72 hours of surgery.
  • Lung injury, defined using international classification of diseases, ninth revision or tenth revision (ICD-9 or ICD-10) diagnosis codes
  • Stroke, defined using international classification of diseases, ninth revision or tenth revision (ICD-9 or ICD-10) diagnosis codes
  • Death within 30 days of surgery
30 days post-surgery

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
30-day mortality
Time Frame: 30 days post-surgery
Death from any cause within 30 days of surgery
30 days post-surgery

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Acute kidney injury
Time Frame: 7 days post-surgery
Incidence of acute kidney injury (AKI), defined according to creatinine based Kidney Disease Improving Global Outcomes criteria, specifically a 0.3 mg/dL or greater increase from baseline within 48 hours or a 50% or greater increase from baseline within seven days of surgery
7 days post-surgery
Myocardial injury
Time Frame: 72 hours post-surgery
Myocardial injury, defined as >99th percentile of normal plasma troponin based on site-specific troponin assay within 72 hours of surgery.
72 hours post-surgery
Lung injury
Time Frame: 30 days post-surgery
Lung injury, defined using international classification of diseases, ninth revision or tenth revision (ICD-9 or ICD-10) diagnosis codes
30 days post-surgery
Stroke
Time Frame: 30 days post-surgery
Stroke, defined using international classification of diseases, ninth revision or tenth revision (ICD-9 or ICD-10) diagnosis codes
30 days post-surgery
Surgical site infection
Time Frame: 30 days post-surgery
Surgical site infection, defined using National Surgical Quality Improvement Program (NSQIP) criteria and reported to NSQIP and also captured using international classification of diseases (ICD) diagnosis data.
30 days post-surgery
Hospital length of stay
Time Frame: Day of hospital discharge
Total number of calendar days from the date of surgery to the date of discharge following the index procedure.
Day of hospital discharge
Hypoxemia
Time Frame: Perioperative
Incidence and duration of SpO₂ values < 80% (in minutes) during maintenance anesthesia (from anesthesia induction to anesthesia emergence).
Perioperative

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Frederic T Billings IV

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
University of Michigan
Multicenter Perioperative Outcomes Group
The Association of University Anesthesiologists

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Frederic T Billings, MD, Vanderbilt University Medical Center

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 1, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
February 1, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
April 1, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
October 31, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 31, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 4, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 16, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 15, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 241806

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data cannot be removed from the MPOG servers where they are stored and analysed. We will review requests for data analyses that use individual patient data, but it would have to be performed inside these servers - i.e., IPD cannot not be shared with others.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

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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