An interventional study of Lower FiO2 and Intermediate FiO2 in Surgeries Undergoing General Anesthesia, sponsored by Frederic T Billings IV. Recruiting at 4 sites in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-16.
Sponsored by Frederic T Billings IV · Not applicable, Interventional, and Treatment
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.
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.
1,691 studies on the registry are indexed under Acute Kidney Injury; 395 are open to participants now.
This study's planned enrollment of 54,000 is above the median of 100 across 817 interventional studies indexed under Acute Kidney Injury.
Browse Acute Kidney Injury studies →This is the only study on the registry with Frederic T Billings IV as lead sponsor.
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 anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
ASA physical status
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Other: Lower FiO2
Other: Intermediate FiO2
Other: Higher FiO2
FiO₂ 0.21-0.40 or lowest FiO₂ to maintain SpO₂ ≥ 94% during maintenance anesthesia
FiO₂ 0.40-0.80 or lowest FiO₂ to maintain SpO₂ ≥ 94% during maintenance anesthesia
FiO₂ \> 0.80 to maintain SpO₂ ≥ 94% during maintenance anesthesia
Composite of organ injury or in-hospital death within 30 days of 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
Time frame: 30 days post-surgery
30-day mortality
Death from any cause within 30 days of surgery
Time frame: 30 days post-surgery
Acute kidney injury
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
Time frame: 7 days post-surgery
Myocardial injury
Myocardial injury, defined as \>99th percentile of normal plasma troponin based on site-specific troponin assay within 72 hours of surgery.
Time frame: 72 hours post-surgery
Lung injury
Lung injury, defined using international classification of diseases, ninth revision or tenth revision (ICD-9 or ICD-10) diagnosis codes
Time frame: 30 days post-surgery
Stroke
Stroke, defined using international classification of diseases, ninth revision or tenth revision (ICD-9 or ICD-10) diagnosis codes
Time frame: 30 days post-surgery
Surgical site infection
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.
Time frame: 30 days post-surgery
Hospital length of stay
Total number of calendar days from the date of surgery to the date of discharge following the index procedure.
Time frame: Day of hospital discharge
Hypoxemia
Incidence and duration of SpO₂ values \< 80% (in minutes) during maintenance anesthesia (from anesthesia induction to anesthesia emergence).
Time frame: Perioperative
Plan to share: No — 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.
No publications or documents are linked to this record.
Started Dec 2025 (actual). Primary completion is estimated for Feb 2028, 26 months after the start.
Of 249 non-industry interventional studies with no phase under Acute Kidney Injury, half reached primary completion within 27 months of starting (the median), counting those still running; a quarter within 12 and three quarters within 44. This study's planned 26 months is close to that.
Counting every sponsor, half of 267 studies reached it within 26 months; a quarter within 12 and three quarters within 44.
How these figures are worked out, and which studies are left out of them.
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