Cerebral Hemodynamic Effects of Oxygen and Antioxidants (CHEOXANT)

NCT07369232 | Recruiting

• 1 other identifier: CEP2024/460
• Study Type: interventional
• Target: 10
• Locations: 1 country
• Sites: 1

Brief 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). 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. 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.

Conditions

Antioxidant; Oxygen; Hyperoxemia; Cerebral Autoregulation; Oxidative Stress

Keywords

oxygen; antioxidant; vitamin c; ascorbic acid; hyperoxia; hyperoxemia; physiology; microcirculation; microperfusion; trancranial doppler; microparticles; cerebral autoregulation

Outcome Measures

Primary Outcomes (2)

• 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).

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

• 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

  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)

• Change in cerebral hemodynamics and autoregulation composite index

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

• Change in skin perfusion

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

Study Arms (2)

Placebo Pre-Treatment + Oxygen

PLACEBO COMPARATOR

Participants 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).

Other: Oxygen

Vitamin C Pre-Treatment + Oxygen

EXPERIMENTAL

Participants 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).

Other: Oxygen; Drug: Vitamin C (Ascorbic Acid)

Interventions

Oxygen OTHER

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

Placebo Pre-Treatment + Oxygen; Vitamin C Pre-Treatment + Oxygen

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

Vitamin C Pre-Treatment + Oxygen

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

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

You may not qualify if:

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

Sponsors & Collaborators

• Erasme University Hospital: lead
• FBM Lab Konsult AB - Sweden: collaborator
• National Research Council Italy - Institute of Clinical Physiology (CNR-IFC): collaborator

Study Sites (1)

Department of Intensive Care - Erasmus Hospital - ULB

Anderlecht, Brussels Capital, 1070, Belgium

RECRUITING

MeSH Terms

Conditions

Hyperoxia

Interventions

Oxygen; Ascorbic Acid

Condition Hierarchy (Ancestors)

Signs and Symptoms, Respiratory; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Chalcogens; Elements; Inorganic Chemicals; Gases; Sugar Acids; Acids, Acyclic; Carboxylic Acids; Organic Chemicals; Hydroxy Acids; Carbohydrates

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Masking Details: Participants are blinded to the intervention (placebo vs. vitamin C infusion). Investigators and care providers are not blinded due to the nature of the procedures.
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Head of Department of Intensive Care

Model Details: 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.

Study Record Dates

• First Submitted: September 18, 2025
• First Posted: January 27, 2026
• Study Start: September 1, 2025
• Primary Completion: January 31, 2026
• Study Completion: February 28, 2026
• Last Updated: January 27, 2026

Record last verified: 2026-01

Locations

BE (1)