Hypoxia, BrainNCT04258774
The Effect of Respiratory Challenge on the BOLD Signal
A study testing Carbon Dioxide in people with Hypoxia, Brain and Hyperoxia, run by Washington University School of Medicine at 1 site in United States.
Trial summary
The purpose of this research study is to better understand how blood flow and metabolism are different between normal controls and patients with disease. The investigators will examine brain blood flow and metabolism using magnetic resonance imaging (MRI). Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Hypoxia, Brain, Hyperoxia, Hypercapnia
- What is being tested?
- Carbon Dioxide
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 48 participants
- Where
- 1 siteUnited States
- Study dates
- 29 Jan 2020to 31 Dec 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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
- Healthy adult subjects (>18 years old) OR adult patients (>18 years old) diagnosed with vascular pathology of the brain willing to participate and sign a consent form.
- Able to participate in MRI scan without sedation
- Not on stimulant medications
- No psychiatric history, as defined by seeing a psychiatrist for medical evaluation and treatment, or taking anti-depressant medications
- No seizure history
- May have occasional headaches if not taking a daily preventative medication for headaches
- Not on vasodilatory medication, such as sildenafil or verapamil
Who cannot join
- Subjects refusing to undergo testing
- Subjects with obstructive or resistive lung disease whose PaCO2 at rest is greater than 50mmHg or whose venous serum bicarbonate is greater than 26 mEq/L
- Subjects with pre-existing respiratory or metabolic acidosis
- Subjects who require portable oxygen at rest or with exercise
- Subjects with chronic heart failure or severe pulmonary disease who are unable to climb one flight of stairs due to shortness of breath
- Subjects with severe heart failure or restrictive lung disease with resting respiratory rate over 15 breaths/min 2. Patients that cannot participate in a course of rehabilitation therapy.
Show all 27Show fewer
- Subjects that cannot undergo an MRI scan due to one of the following indications:
- Pregnancy
- Obtundation, or Coma
- Confusion, Delirium, or Dementia
- Unable to understand or carry out commands regarding keeping still and breathing pattern
- Increased intracranial pressure due to space occupying lesion or obstruction of outflow of CSF
- Claustrophobia
- History of kidney problems
- Pace makers
- Skin tattoos
- Neurostimulators (TENS-unit)
- Implanted drug infusion device (i.e., insulin pump)
- Exposure of metal fragments to your eye
- Artificial heart valves
- Aneurysm clips
- Cochlear implants
- Metallic implants and prosthesis
- Vascular stent or stent graft
- History as a metal worker
- Shrapnel or bullet wounds
- Dorsal column stimulators
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site
Washington University of St. Louis
St Louis, Missouri, 63110
About this study
The purpose of this research study is to better understand how blood flow and metabolism are different between normal controls and patients with disease.
The investigators will examine brain blood flow and metabolism using magnetic resonance imaging (MRI). The brain's blood vessels expand and constrict to regulate blood flow based on the brain's needs. The amount of expanding and contracting the blood vessels can do varies by age. The brain's blood flow changes in small ways during everyday activities, such as normal brain growth, exercise, or deep concentration. Significant illness or physiologic stress may increase the brain's metabolic demand or cause other bigger changes in blood flow. If blood vessels are not able to expand to give more blood flow when metabolic demand is high, the brain may not get all of the oxygen it needs. In less extreme circumstances, not having as much oxygen as it wants may cause the brain to grow and develop more slowly than it should.
One way to test the ability of the blood vessels to expand is by measuring blood flow while breathing in carbon dioxide (CO2). CO2 causes blood vessels in the brain to dilate without increasing brain metabolism. The study team will use a special mask to control the amount of oxygen and carbon dioxide patients breath in so that we can study how their brain reacts to these changes. This device designed to simulate carbon dioxide levels achieved by a breath-hold and target the concentration of carbon dioxide in the blood in breathing patients. The device captures exhaled gas and provides an admixture of fresh gas and neutral/expired gas to target different carbon dioxide levels while maintaining a fixed oxygen level. The study team will obtain MRI images of the brain while the subjects are breathing air controlled by the device.
- Conditions
- Hypoxia, Brain, Hyperoxia, Hypercapnia, Hypocapnia
- Being tested
- Carbon Dioxide
- Keywords
- brain metabolism, oxygen extraction fraction, cerebral vascular reactivity, carbon dioxide
- Medical subject headings
- Hypoxia, Brain, Hyperoxia, Hypercapnia, Hypocapnia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Carbon DioxideOther
The study team will administer inhaled carbon dioxide to the participants during an MRI at a level
| Study group | Role | What they receive |
|---|---|---|
| Healthy Adults | Active comparator | Not described Receives: Other: Carbon Dioxide |
| Adults diagnosed with vascular pathology of the brain | Active comparator | Not described Receives: Other: Carbon Dioxide |
What is being measured
The primary outcome is the main question the study is designed to answer.
Cerebral Oxygen Metabolism
Measured: From the beginning of the MRI scan to the completion of the MRI scan -- 75 minutes.
Secondary outcomes (1)
Cerebrovascular Reactivity
Measured: From administration of carbon dioxide to end of inhalation of carbon dioxide -- 15 minutes.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Feb 2020
- Study start29 Jan 2020
- Primary completion31 Dec 2027 (estimated)
- Study completion31 Dec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Hypoxia, BrainStudies of the same condition, open and under way.
- More trials run by Washington University School of MedicineThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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
- Other
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Model description
- All arms will receive the same study conditions.
- Masking
- None (open label)
- Enrolment
- 48 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Washington University School of Medicine
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04258774
- Sponsor's protocol ID
- 201910105
- Status last verified
- Jan 2026
- First submitted
- 3 Feb 2020
- Last updated
- 16 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 16 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Respiratory Challenge on the BOLD Signal
- ClinicalTrials.gov ID
- NCT04258774
- Acronym / sponsor ID
- 201910105
- Conditions
- Hypoxia, Brain, Hyperoxia, Hypercapnia, Hypocapnia
- Keywords
- brain metabolism, oxygen extraction fraction, cerebral vascular reactivity, carbon dioxide
- Study type
- Interventional
- Recruitment status
- Enrolling by invitation
- Enrolment
- 48 participants (estimated)
- Lead sponsor
- Washington University School of MedicineUniversity, hospital or other
- Study start
- 29 Jan 2020 (actual)
- Primary completion
- 31 Dec 2027 (estimated)
- Study completion
- 31 Dec 2027 (estimated)
- First posted
- 6 Feb 2020 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this research study is to better understand how blood flow and metabolism are different between normal controls and patients with disease.
The investigators will examine brain blood flow and metabolism using magnetic resonance imaging (MRI). The brain's blood vessels expand and constrict to regulate blood flow based on the brain's needs. The amount of expanding and contracting the blood vessels can do varies by age. The brain's blood flow changes in small ways during everyday activities, such as normal brain growth, exercise, or deep concentration. Significant illness or physiologic stress may increase the brain's metabolic demand or cause other bigger changes in blood flow. If blood vessels are not able to expand to give more blood flow when metabolic demand is high, the brain may not get all of the oxygen it needs. In less extreme circumstances, not having as much oxygen as it wants may cause the brain to grow and develop more slowly than it should.
One way to test the ability of the blood vessels to expand is by measuring blood flow while breathing in carbon dioxide (CO2). CO2 causes blood vessels in the brain to dilate without increasing brain metabolism. The study team will use a special mask to control the amount of oxygen and carbon dioxide patients breath in so that we can study how their brain reacts to these changes. This device designed to simulate carbon dioxide levels achieved by a breath-hold and target the concentration of carbon dioxide in the blood in breathing patients. The device captures exhaled gas and provides an admixture of fresh gas and neutral/expired gas to target different carbon dioxide levels while maintaining a fixed oxygen level. The study team will obtain MRI images of the brain while the subjects are breathing air controlled by the device.
Study design
- Primary purpose
- Other
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- All arms will receive the same study conditions.
| Arm | Type | Receives |
|---|---|---|
| Healthy Adults | Active comparator | Other: Carbon Dioxide |
| Adults diagnosed with vascular pathology of the brain | Active comparator | Other: Carbon Dioxide |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- Healthy adult subjects (>18 years old) OR adult patients (>18 years old) diagnosed with vascular pathology of the brain willing to participate and sign a consent form.
- Able to participate in MRI scan without sedation
- Not on stimulant medications
- No psychiatric history, as defined by seeing a psychiatrist for medical evaluation and treatment, or taking anti-depressant medications
- No seizure history
Key exclusion criteria (27 listed)
- Subjects refusing to undergo testing
- Subjects with obstructive or resistive lung disease whose PaCO2 at rest is greater than 50mmHg or whose venous serum bicarbonate is greater than 26 mEq/L
- Subjects with pre-existing respiratory or metabolic acidosis
- Subjects who require portable oxygen at rest or with exercise
- Subjects with chronic heart failure or severe pulmonary disease who are unable to climb one flight of stairs due to shortness of breath
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Carbon DioxideThe study team will administer inhaled carbon dioxide to the participants during an MRI at a level | Other | Adults diagnosed with vascular pathology of the brain, Healthy Adults |
Primary outcome
Cerebral Oxygen Metabolism
Time frame: From the beginning of the MRI scan to the completion of the MRI scan -- 75 minutes.
1 secondary outcome
Cerebrovascular Reactivity
Time frame: From administration of carbon dioxide to end of inhalation of carbon dioxide -- 15 minutes.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Jan 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Carbon Dioxide in people with Hypoxia, Brain and Hyperoxia, run by Washington University School of Medicine at 1 site in United States.
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 7 inclusion and 27 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: enrolling by invitation, as of the sponsor's last update on 16 Jan 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 United States. 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. 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?
This study is still under way. Results are not available in the source record yet.
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?
Cerebral Oxygen Metabolism (time frame: From the beginning of the MRI scan to the completion of the MRI scan -- 75 minutes.). 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 16 Jan 2026.