Neuroimaging During Pure Oxygen Breathing
Condition: Hyperoxia; Hypoxia, Brain; Neurobehavioral Manifestations
MeSH terms: Neurobehavioral Manifestations; Hypoxia, Brain; Hypoxia; Hyperoxia
Intervention: Oxygen
Intervention description: Persons will undergo MRI, EEG, and complete computerized cognitive testing in baseline room air. Persons will then breathe 100% pure oxygen and undergo MRI, EEG, and complete computerized cognitive testing. Persons will serve as their own controls.
Phase: Phase 4
Study type: Interventional
Primary purpose: Basic Science
Intervention model: Single Group Assignment
Intervention model description: All participants will undergo neuroimaging (MRI) with electroencephalographic (EEG) cortical network mapping and cognitive assessments during room air breathing (placebo). Room air (21% inspired oxygen) will be delivered via non-rebreather face mask. Persons will serve as their own control and will next undergo neuroimaging (MRI) with electroencephalographic (EEG) cortical network mapping and cognitive assessments during pure oxygen breathing. Pure oxygen (100% inspired oxygen) will be delivered via non-rebreather face mask
Masking: None (Open Label)
Enrollment: 33.0
Sex: All
Minimum age: 18 Years
Maximum age: 60 Years
Healthy volunteers: Accepts Healthy Volunteers
Keywords: Hyperoxia; Hypoxia, Brain

Summary:

      The investigators will conduct a non-randomized clinical trial to examine the effect of pure
      oxygen breathing on the brain. The study will compare cerebral blood flow, cortical
      electrical activity, and cognitive performance in 32 persons during room air (21% oxygen)
      breathing and pure oxygen (100% oxygen) breathing. Subjects will be used as their own
      controls. The investigators aim to:

        1. Determine whether breathing 100% oxygen changes blood flow through the brain. The
           investigators will learn whether brain blood flow is increased, decreased or stays the
           same.

        2. Determine if changes that might occur in brain blood flow are also accompanied by
           changes in the brain's electrical activity (EEG).

        3. Learn whether changes in the speed at which the brain processes information (cognitive
           function) accompany changes in brain blood flow and electrical activity that may be
           seen.
    

Eligibility criteria:

        Inclusion Criteria:

          1. Persons recruited from currently approved Human Subject Panel for high altitude
             studies at Wright Patterson Air Force Base, Dayton, OH. Volunteers will have
             documentation of past exposure to hypobaric conditions, either from past high-altitude
             flight, as hypobaric chamber personnel, or as participants in previous/current high
             altitude studies. Persons without past exposure to hypobaric conditions were also
             eligible to participate.

          2. Height 152.5-195.5 cm, weight 40-135 kg.

        Exclusion Criteria:

          1. Persons who have contraindications to MRI such as cardiac pacemakers, intracranial
             aneurysm clips, metallic implants or external clips within 10 mm of the head;
             implanted metallic devices such as pumps or previously implanted neurostimulation
             devices; cochlear implants, defibrillators, pacing wires, body piercings that cannot
             be removed, metal filings such as shrapnel, tattoos on the head and neck, or medical
             conditions contraindicated for MRI safety.

          2. History of claustrophobia