Neuroimaging During Pure Oxygen Breathing
Condition: Hyperoxia; Hypoxia, Brain; Neurobehavioral Manifestations
MeSH terms: Neurobehavioral Manifestations; Hypoxia, Brain; Hypoxia; Hyperoxia
Study type: Interventional
Phase: Phase 4

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.
    

Detailed description: 
      The investigators will conduct a crossover design clinical trial to compare the effect of
      room air breathing (21% inspired oxygen) with pure oxygen breathing (100% inspired oxygen) on
      brain blood flow and cortical electrical activity. The study involves a one-time data
      collection taking place at University Hospitals Cleveland Medical Center on the Case Western
      Reserve University campus in Cleveland, Ohio. The investigators will perform neuroimaging
      (MRI) with electroencephalographic (EEG) cortical network mapping and cognitive assessments
      in all participants during room air breathing and again while breathing 100% pure oxygen.
      Oxygen will be delivered through a non-rebreather mask. Arterial blood partial pressure of
      oxygen (PaO2) will be measured twice, from arterial blood samples drawn during breathing room
      air prior to the MRI scan and again after 30 minutes of breathing 100% oxygen immediately
      following neuroimaging. Thus, the investigators will be able to determine if breathing pure
      oxygen may temporarily change brain blood flow and breathing, leading to changes in cognitive
      status such as euphoria or slowed reflexes. Information gained in this study may have direct
      operational relevance by helping us to understand one potential cause of "Unexplained
      Physiologic Events" that are reported in some aircraft pilots when flying at high altitude.
      Information gained could lead to development of new gas mixtures for use by personnel working
      in low oxygen high altitude environments.
    

Intervention name(s): Oxygen
Intervention type(s): Drug
Intervention description(s): 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.
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)
Primary purpose: Basic Science
Keywords: Hyperoxia; Hypoxia, Brain