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OxygenCHEOXANTNCT07369232

Cerebral Hemodynamic Effects of Oxygen and Antioxidants (CHEOXANT)

A study testing Oxygen and Vitamin C (Ascorbic Acid) in people with Oxygen and Hyperoxemia, run by Erasme University Hospital at 1 site in Belgium.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

This study is called CHE-OX-ANT (Cerebral Hemodynamic Effects of Oxygen and Antioxidants). It is a single-center, academic research project led by the Department of Intensive Care at Erasme Hospital (Université Libre de Bruxelles). Read more about this study

Who is it for?
Ages 18 years and olderHealthy volunteers can take part
Conditions the study is for
Oxygen, Hyperoxemia, Antioxidant
What is being tested?
Oxygen and Vitamin C (Ascorbic Acid)
Type of treatment
Injection or infusion
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
13 participants
Where
1 siteBelgium
Study dates
1 Sep 2025to 30 Apr 2026
Phase
Interventional
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • Healthy volunteers accepted
  • Adult, Older adult

Who may be able to join

  • Adults
  • Otherwise healthy, without known pathologies in the cardiovascular, neurological, immunological, renal hematological, or vascular systems.

Who cannot join

  • Smokers
  • Pregnant women
  • BMI > 25
  • Any reason to avoid vit. C
  • Any reason to avoid breathing oxygen at high doses

Trial locations and contacts

1 site in 1 country.

Belgium1 site
  • Department of Intensive Care - Erasmus Hospital - ULB

    Anderlecht, Brussels Capital, 1070

Other trials in Belgium

About this study

Official title: Cerebral Hemodynamic Effects of Oxygen and Antioxidants

This study is called CHE-OX-ANT (Cerebral Hemodynamic Effects of Oxygen and Antioxidants). It is a single-center, academic research project led by the Department of Intensive Care at Erasme Hospital (Université Libre de Bruxelles).

The study focuses on understanding how the brain and blood vessels react when a person breathes pure oxygen and how these effects may be influenced by giving vitamin C, an antioxidant. Oxygen is one of the most common treatments in hospitals. While it can be life-saving, too much oxygen may sometimes cause harmful effects, such as oxidative stress (an imbalance between damaging molecules called free radicals and the body's defenses). Antioxidants like vitamin C may help counteract these effects.

Read more

The goal of the study is to examine how a short period of high oxygen (30 minutes of 100% oxygen through a mask) affects cerebral hemodynamics, microcirculation, microperfusion, blood markers (levels of oxidative stress, antioxidant activity, and microparticles).

The study will also test whether giving vitamin C beforehand changes these responses compared to a placebo (saline solution).

Each volunteer will participate in two sessions, one week apart. Before each session, participants will receive either vitamin C (given intravenously) or a placebo (saline). They will not know which one they receive.

Then, they will breathe 100% oxygen for 30 minutes through a facial mask. Measurements will be taken at three times: before oxygen (t0), just after oxygen (t1), and 1 hour later (t2). These include: ultrasound of the brain's blood flow (transcranial Doppler), measurements of skin perfusion and blood samplings.

Read the detailed description

Oxygen therapy is widely used in hospitals and critical care, but excessive oxygen levels (hyperoxemia) can have both beneficial and harmful effects. In the brain, high oxygen may improve oxygen delivery, but it can also trigger oxidative stress, inflammation, and vascular dysfunction, potentially worsening outcomes. Antioxidants, such as vitamin C (ascorbic acid), may counteract these harmful effects by neutralizing reactive oxygen species and restoring redox balance. The CHE-OX-ANT study aims to investigate the physiological effects of a short normobaric hyperoxic stimulus (30 minutes of 100% oxygen breathing) in healthy volunteers, with and without prior antioxidant administration. The primary focus is on oxidative stress markers and microparticle production, while secondary objectives include effects on cerebral blood flow, sublingual microcirculation, and skin perfusion.

This is a prospective, interventional, single-center, randomized, single-blind, placebo-controlled physiological trial conducted at Erasme Hospital, Brussels. Each subject will serve as their own control, undergoing two study sessions one week apart. The study will recruit 10-15 healthy adult volunteers. Eligible participants must be >18 years old, in good health, with no cardiovascular, neurological, hematological, or immunological disease. Exclusion criteria include smoking, pregnancy, BMI >25, or contraindications to oxygen or vitamin

At each session, participants will receive one of two randomized pre-treatments, administered intravenously 30-60 minutes before oxygen exposure:

Vitamin C group: 1-3 g ascorbic acid in 500 mL saline infused over 20 minutes. Placebo group: 500 mL of saline infused over 20 minutes. Following this, participants will breathe 100% oxygen for 30 minutes through a reservoir mask. Measurements will be obtained at three timepoints: baseline (t0), immediately after oxygen (t1), and 2 hours post-exposure (t2).

Cerebral hemodynamics: Transcranial Doppler ultrasonography. Skin perfusion: laser Doppler or infrared techniques. Blood samples: venous and arterial blood for oxidative stress, antioxidant status, microparticles, and arterial blood gas analysis.

Blood pressure: continuous invasive monitoring via a radial arterial catheter. Endpoints Primary endpoint: Change in oxidative stress and microparticle levels. Secondary endpoints: Changes in cerebral hemodynamics and skin perfusion. This exploratory study will provide new insights into how oxygen affects the brain and peripheral perfusion, and whether antioxidant administration modifies these effects. The results may contribute to optimizing oxygen therapy in critically ill patients, where oxygen is widely used but may sometimes cause harm.

Being tested
Oxygen, Vitamin C (Ascorbic Acid)
Keywords
oxygen, antioxidant, vitamin c, ascorbic acid, hyperoxia, hyperoxemia, physiology, microcirculation, microperfusion, trancranial doppler, microparticles, cerebral autoregulation
Medical subject headings
Hyperoxia

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • OxygenOther

    30 minutes of normobaric 100% oxygen via reservoir mask 15L/min

  • Vitamin C (Ascorbic Acid)Drug

    2 g ascorbic acid (vitamin C - ascorbic acid) diluted in 250 mL saline over 20 minutes, 30-60 minutes before breathing 100% oxygen

Study groups in NCT07369232
Study groupRoleWhat they receive
Placebo Pre-Treatment + OxygenPlacebo comparatorParticipants receive an intravenous infusion of 250 mL saline (placebo) over 20 minutes, 30-60 minutes before breathing 100% oxygen for 30 minutes through a reservoir mask. Measurements are performed at baseline, immediately after oxygen, and 1 hour later (cerebral blood flow by transcranial Doppler and skin microperfusion, blood pressure, arterial blood gases, oxidative stress markers, and microparticles).
Receives: Other: Oxygen
Vitamin C Pre-Treatment + OxygenExperimentalParticipants receive an intravenous infusion of 2 g ascorbic acid (vitamin C - ascorbic acid) diluted in 250 mL saline over 20 minutes, 30-60 minutes before breathing 100% oxygen for 30 minutes through a reservoir mask. Measurements are performed at baseline, immediately after oxygen, and 1 hour later (cerebral blood flow by transcranial Doppler and skin perfusion, blood pressure, arterial blood gases, oxidative stress markers, and microparticles).
Receives: Other: Oxygen; Drug: Vitamin C (Ascorbic Acid)

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Change in circulating microparticle concentration (total MPs - EV)

    A composite extracellular vesicle (MPs - EV) outcome reflecting brain and cerebral endothelial responses to hyperoxia, quantified in plasma by flow cytometry. The composite index will be derived from the standardized (z-score) change from baseline of the following EV subpopulations:

    GFAP-positive EVs (astrocyte-derived EVs) Aquaporin-4 (AQP4)-positive EVs (astrocyte/BBB-related EVs) TMEM119-positive EVs (microglia-related EVs) VE-cadherin (CD144)-positive EVs (endothelial junction-related EVs) CD62E (E-selectin)-positive EVs (endothelial activation-related EVs) Each EV subpopulation will be quantified as concentration (EVs/µL plasma). For each participant and time point, individual EV concentrations will be normalized (z-transformed) and combined into a single composite EV score by averaging the standardized values.

    The reported metric will be the within-participant change in the composite EV score from baseline (Δt1-t0 and Δt2-t0).

    Measured: t0 = baseline (before infusion/oxygen administration) t1 = immediately after 30 minutes of 100% O₂ t2 = 1 hour after the end of exposure (post-exposure)

  2. Change in oxidative stress and antioxidant status

    A composite biochemical outcome reflecting systemic oxidative stress and antioxidant balance in response to hyperoxia and vitamin C administration. The composite index will be derived from the standardized (z-score) change from baseline of the concentrations of the erythrocyte biomarker of antioxidant defense in mg/dL.

    For each participant and time point, biomarker values will be normalized (z-transformed) and combined

    Measured: t0 = baseline (before infusion/oxygen administration) t1 = immediately after 30 minutes of 100% O₂ t2 = 1 hour after the end of exposure (post-exposure)

Secondary outcomes (2)
  1. Change in cerebral hemodynamics and autoregulation composite index

    A composite outcome summarizing cerebral hemodynamic and autoregulatory responses to hyperoxia, derived from transcranial Doppler (TCD) and arterial blood pressure signals. Dynamic cerebral autoregulation index (Mx, unitless) calculated using a predefined MATLAB/Python algorithm.

    For each participant and time point, it will be expressed as change from baseline and standardized (z-score), then combined into a single composite score by averaging the standardized component changes. The reported metric will be the within-participant change in the composite index from baseline

    Measured: t0 = baseline (before infusion/oxygen administration) t1 = immediately after 30 minutes of 100% O₂ t2 = 1 hour after the end of exposure (post-exposure)

  2. Change in skin perfusion

    Skin microcirculation will be assessed at a standardized site (fingertip) under controlled ambient temperature and resting conditions. The primary and only reported variable will be skin microvascular blood flow, expressed in perfusion units (PU) and measured using a validated microcirculatory technique.

    For each participant and time point, values will be averaged over predefined short acquisition windows to reduce signal variability. The reported metric will be the within-participant change in skin perfusion from baseline, expressed as absolute change in PU (Δt1-t0 and Δt2-t0).

    Skin temperature and relative (%) changes will be monitored only for quality control purposes and will not be reported as outcome measures.

    Measured: t0 = baseline (before infusion/oxygen administration) t1 = immediately after 30 minutes of 100% O₂ t2 = 1 hour after the end of exposure (post-exposure)

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted27 Jan 2026
  2. Study start1 Sep 2025
  3. Primary completion31 Mar 2026
  4. Study completion30 Apr 2026

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase N/A
Primary purpose
Basic science
Allocation
Randomised
Intervention model
Crossover
Model description
This is a single-center, randomized, single-blind, placebo-controlled, crossover physiological study. Each volunteer undergoes two sessions, spaced at least one week apart, receiving vitamin C in one session and a placebo in the other, in randomized order.
Masking
Single blind
Who is masked
Participant
Enrolment
13 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07369232
Sponsor's protocol ID
CEP2024/460
Acronym
CHEOXANT
Status last verified
May 2026
First submitted
18 Sep 2025
Last updated
19 May 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Undecided: At present, there is no confirmed plan to share individual participant data (IPD). If sharing is pursued, it would involve de-identified datasets limited to physiological parameters, oxidative stress markers, microparticle levels, and circulatory measurements. No personally identifiable information will be shared.

Questions about this trial

What is this clinical trial studying?

A study testing Oxygen and Vitamin C (Ascorbic Acid) in people with Oxygen and Hyperoxemia, run by Erasme University Hospital at 1 site in Belgium.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 2 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 19 May 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Belgium. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Change in circulating microparticle concentration (total MPs - EV) (time frame: t0 = baseline (before infusion/oxygen administration) t1 = immediately after 30 minutes of 100% O₂ t2 = 1 hour after the end of exposure (post-exposure)). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 19 May 2026.

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