Neuroimaging During Pure Oxygen Breathing

October 25, 2019 updated by: Michael J. Decker, Case Western Reserve University

Hyperoxia: An Unrecognized Mechanism for Inducing "Hypoxia-Like" Symptoms

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.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

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.

Study Type

Interventional

Enrollment (Actual)

33

Phase

  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Ohio
      • Cleveland, Ohio, United States, 44106
        • Case Western Reserve University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 60 years (ADULT)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: BASIC_SCIENCE
  • Allocation: NA
  • Interventional Model: SINGLE_GROUP
  • Masking: NONE

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
EXPERIMENTAL: All Study Participants
Breathing 21% oxygen via non-rebreather face mask followed by breathing 100% oxygen via non-rebreather face mask
Drug: Oxygen
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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Cerebral Blood Flow
Time Frame: Baseline and at 30 minutes
Change in brain blood flow from Baseline Room Air breathing (21% inspired oxygen) to Pure Oxygen breathing (100% inspired oxygen). Measured using Magnetic Resonance Imaging (MRI).
Baseline and at 30 minutes

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Cortical Network Activity
Time Frame: Baseline and at 30 minutes
Change in alpha cortical electrical activity in the temporal brain region from Baseline Room Air breathing (21% inspired oxygen) to Pure Oxygen breathing (100% inspired oxygen). Measured using MRI-compatible 64-electrode high-density electroencephalography (EEG).
Baseline and at 30 minutes
Cognitive Performance
Time Frame: Baseline and at 30 minutes
Change in cognitive performance from Baseline Room Air breathing (21% inspired oxygen) to Pure Oxygen breathing (100% inspired oxygen). Measured using the General Cognitive Function score on the MicroCog^TM Assessment of Cognitive Functioning (TM= trademark of Pearson Education, Inc., New York, NY). The computer-administered MicroCog measures changes in cognitive performance in 9 domains related to attention, memory, reasoning, spatial processing, and reaction time. The General Cognitive Function score is a summed score and measures accuracy and speed processing. Education-adjusted Standardized Scores used to compare each study participant against population norms. Higher scores are indicative of better performance. Index Standardized Scores of 69 and below are considered Below Average; scores of 70-84 are considered Low Average; scores of 85-114 are considered to be Average; and scores of 115 and above are considered to be Above Average.
Baseline and at 30 minutes

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Case Western Reserve University

Investigators

  • Principal Investigator: Michael J Decker, PhD, Case Western Reserve University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (ACTUAL)

October 2, 2017

Primary Completion (ACTUAL)

May 2, 2018

Study Completion (ACTUAL)

May 9, 2018

Study Registration Dates

First Submitted

August 25, 2017

First Submitted That Met QC Criteria

August 30, 2017

First Posted (ACTUAL)

August 31, 2017

Study Record Updates

Last Update Posted (ACTUAL)

November 13, 2019

Last Update Submitted That Met QC Criteria

October 25, 2019

Last Verified

October 1, 2019

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • CON215044
  • FA8650-12-D6280 TO0052 (OTHER_GRANT: KBRWyle (for Wright Patterson Air Force Base))

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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