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NCT Number: NCT07224243

Impact of Intraoperative Oxygenation Practices on Patient Outcomes

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.

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Key information

Conditions

Surgeries Undergoing General Anesthesia Acute Kidney Injury Brain Diseases Cardiovascular Diseases Central Nervous System Diseases Cerebrovascular Disorders Female Urogenital Diseases Female Urogenital Diseases and Pregnancy Complications Kidney Diseases Lung Diseases Lung Injury Male Urogenital Diseases Nervous System Diseases Renal Insufficiency Respiratory Tract Diseases Stroke Thoracic Injuries Urogenital Diseases Urologic Diseases Vascular Diseases Wounds and Injuries

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University of Michigan Hospital, Ann Arbor, Michigan, United States

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About this study

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.

Who can participate

Healthy volunteers accepted: No

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

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.

Treatment and study plan

Lower FiO2

Other

FiO₂ 0.21-0.40 or lowest FiO₂ to maintain SpO₂ ≥ 94% during maintenance anesthesia

Intermediate FiO2

Other

FiO₂ 0.40-0.80 or lowest FiO₂ to maintain SpO₂ ≥ 94% during maintenance anesthesia

Higher FiO2

Other

FiO₂ > 0.80 to maintain SpO₂ ≥ 94% during maintenance anesthesia

Primary outcomes

  1. 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

Secondary outcomes

  1. 30-day mortality

    Time frame: 30 days post-surgery

    Death from any cause within 30 days of surgery

Other outcomes

  1. 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

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. Hypoxemia

    Time frame: Perioperative

    Incidence and duration of SpO₂ values < 80% (in minutes) during maintenance anesthesia (from anesthesia induction to anesthesia emergence).

Study contacts

Contact information is provided by the study sponsor or research team.

Tracie Baker, CCRA

CONTACT

[email protected]

6158751852

Sponsors and collaborators

Lead sponsor

Frederic T Billings IV

Other

Collaborators

  • Multicenter Perioperative Outcomes Group
  • The Association of University Anesthesiologists
  • University of Michigan

Registry information

Acronym: IntraOp Ox

Important dates

Study start
2025
Primary completion
2028
Study completion
2028
First posted
Nov 4, 2025
Registry last updated
Jun 10, 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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