HYPER MIND - Hyperoxia Effects on Cerebral Hemodynamics

NCT07377162 | Recruiting

• 1 other identifier: SRB2023205
• Study Type: interventional
• Target: 80
• Locations: 1 country
• Sites: 1

Brief Summary

This study aims to better understand how short periods of exposure to high oxygen levels affect blood flow in the brain of patients who are intubated and mechanically ventilated in the Intensive Care Unit (ICU). Many ICU patients receive more oxygen than strictly necessary, and high blood oxygen levels (hyperoxemia) are very common. However, the immediate effects of short hyperoxic exposures on cerebral circulation and autoregulation remain poorly understood. In this study, patients who already require mechanical ventilation for medical reasons will undergo a brief and controlled increase in the oxygen delivered through the ventilator (FiO₂). During this time, we will continuously monitor blood flow in one of the main brain arteries using a non-invasive ultrasound technique called transcranial Doppler (TCD). The goal is to evaluate how cerebral blood flow, pulsatility, and autoregulatory capacity change during and after a short hyperoxic stimulus. No additional invasive procedures are required beyond standard ICU monitoring, except for the temporary adjustment of the ventilator's oxygen settings and arterial blood gas sampling, which are part of usual care in critically ill patients. Participation does not provide direct clinical benefit but may help improve future oxygen management in ICU patients. The study involves minimal risk, as short hyperoxic exposures are already common in routine care and will be interrupted immediately in case of any adverse event.

Conditions

Hyperoxemia; Cerebrovascular Circulation; Cerebral Autoregulation; Critical Illness; Mechanical Ventilation

Keywords

hyperoxemia; brain hemodynamics; tcd; cerebral autoregulation; Critical Illness; intensive care unit; hyperoxia; oxygen

Outcome Measures

Primary Outcomes (1)

• Change in Mean Flow Index (Mx) During Normobaric Hyperoxia

  Dynamic cerebral autoregulation will be assessed using the mean flow index (Mx), calculated as the moving Pearson correlation coefficient between mean arterial pressure (MAP) and mean middle cerebral artery (MCA) blood flow velocity measured by transcranial Doppler ultrasonography. The outcome will be reported as the absolute change in Mx from baseline, calculated as the average Mx value during normobaric hyperoxia minus the baseline average.

  Baseline (prior to hyperoxic exposure), during normobaric hyperoxia steps, assessed during the intervention period, and after returning to baseline (assessed up to 20 minutes)

Secondary Outcomes (4)

• Change in Middle Cerebral Artery Cerebral Blood Flow During Normobaric Hyperoxia

  Baseline (prior to hyperoxic exposure), during normobaric hyperoxia, assessed during the intervention period (up to 30 minutes per study session), and after returning to baseline (assessed up to 20 minutes)

• Change in Autoregulation Index (ARI) During Normobaric Hyperoxia

  Baseline (prior to hyperoxic exposure), during normobaric hyperoxia, assessed during the intervention period (up to 30 minutes per study session), and after returning to baseline (assessed up to 20 minutes)

• Change in Transfer Function Analysis Parameters During Normobaric Hyperoxia

  Baseline (prior to hyperoxic exposure), during normobaric hyperoxia, assessed during the intervention period (up to 30 minutes per study session), and after returning to baseline (assessed up to 20 minutes)

• Change in Transfer Function Analysis Parameters During Normobaric Hyperoxia

  Baseline (prior to hyperoxic exposure), during normobaric hyperoxia, assessed during the intervention period (up to 30 minutes per study session), and after returning to baseline (assessed up to 20 minutes)

Study Arms (1)

Experimental: Hyperoxic Stimulus

EXPERIMENTAL

Participants receive one or two brief normobaric hyperoxic (NBHO) stimuli during mechanical ventilation. The inspired fraction of oxygen (FiO₂) is transiently increased to 0.5 or 1.0 depending on baseline FiO₂ requirements. Cerebral blood flow and autoregulation are continuously monitored using transcranial Doppler ultrasound.

Other: Normobaric Hyperoxic Stimulus (NBHO)

Interventions

Normobaric Hyperoxic Stimulus (NBHO) OTHER

The intervention consists of a short, controlled increase in the inspired oxygen fraction (FiO₂) delivered by the mechanical ventilator. Depending on baseline FiO₂, patients will receive: Depending on baseline FiO₂, patients will receive: Two-step NBHO (baseline FiO₂ \< 0.5): FiO₂ raised to 0.5 and then to 1.0 One-step NBHO (baseline FiO₂ ≥ 0.5): FiO₂ raised to 1.0 Each step includes 5 minutes to reach steady state followed by a 10-minute recording period. Cerebral blood flow velocity and autoregulation are continuously assessed using transcranial Doppler ultrasound.

Experimental: Hyperoxic Stimulus

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Adult patients aged ≥18 years
• Admitted to the intensive care unit (ICU)
• Intubated and mechanically ventilated for ≤72 hours
• Receiving volume-controlled mechanical ventilation
• Arterial partial pressure of carbon dioxide (PaCO₂) between 35 and 45 mmHg
• Invasive arterial blood pressure monitoring in place
• Adequate transcranial Doppler (TCD) acoustic window
• Clinically judged to be suitable for a brief normobaric hyperoxic stimulus
• Expected to receive one or two hyperoxic steps based on baseline FiO₂ requirements: a) Baseline FiO₂ \< 0.5: two-step hyperoxic stimulus (FiO₂ 0.5 followed by FiO₂ 1.0); b) Baseline FiO₂ ≥ 0.5: one-step hyperoxic stimulus (FiO₂ 1.0)

You may not qualify if:

• Age \<18 years
• Pregnancy
• Extracorporeal membrane oxygenation (ECMO)
• Continuous renal replacement therapy (CRRT)
• Contraindications to hyperoxia, as judged by the treating physician
• Severe hemodynamic instability requiring changes in vasopressor dose during the recording period
• Inability to obtain a reliable transcranial Doppler signal through the temporal acoustic windows
• Any clinical condition deemed by the treating physician to pose unacceptable risk during hyperoxic exposure

Sponsors & Collaborators

• Erasme University Hospital: lead

Study Sites (1)

Erasme Hospital - ULB

Brussels, Belgium

RECRUITING

MeSH Terms

Conditions

Critical Illness; Choroideremia; Hyperoxia

Condition Hierarchy (Ancestors)

Disease Attributes; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Eye Diseases, Hereditary; Eye Diseases; Choroid Diseases; Uveal Diseases; Genetic Diseases, Inborn; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Genetic Diseases, X-Linked; Signs and Symptoms, Respiratory; Signs and Symptoms

Study Officials

• Fabio Silvio Taccone, MD, PhD

  Hôpital Erasme - Université Libre de Bruxelles (ULB)

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Michele Salvagno, MD

CONTACT

+32471386614; michele.salvagno@ulb.be

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Masking Details: Not applicable. This physiological study cannot be masked due to the nature of FiO₂ manipulation and continuous hemodynamic monitoring.
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: MD, PHD

Model Details: Participants will undergo one or two controlled hyperoxic stimuli depending on baseline FiO₂. All participants receive the same physiological intervention consisting of a brief increase in inspired oxygen fraction (FiO₂), with cerebral hemodynamics monitored using continuous transcranial Doppler. No randomization is performed.

Study Record Dates

• First Submitted: December 11, 2025
• First Posted: January 29, 2026
• Study Start: January 1, 2024
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2028
• Last Updated: January 29, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will not share

Locations

BE (1)