Why we are doing this study:This study was designed to determine how the brain responds to breathing various concentrations of oxygen that rapidly fluctuate, over a 1½ to 2 hour period. This is the time frame that oxygen is used by military pilots in an average flight. The study will take place in a hypobaric chamber, a room that can simulate a high altitude environment by changing the barometric pressure. Information from this study will be used to provide a more complete understanding of how the brain responds during supplemental oxygen breathing at various altitudes. This information could help guide the structure of oxygen delivery schedules to provide the greatest level of life support at high altitudes, with minimal side effects.
Our Primary Goal is: to establish how the brain responds to breathing various concentrations of oxygen that fluctuate over several minutes. We will measure this using a functional near-infrared spectroscopy (fNIRS) system to obtain images of brain oxygenation at various concentrations of alternating oxygen levels.
We are also asking: if different alterations of oxygen breathing affects how the brain performs. We will measure this with cognitive testing during the fNIRS data collection.
We will also learn whether: inflammatory markers (a coping mechanism for the body) are released in the blood in response to fluctuating oxygen levels and changes in barometric pressure.
What is involved?
One 3 hour study visit at University Hospitals Cleveland inside the hypobaric chamber where cognitive testing will be done at variable oxygen levels. The oxygen levels will always be at or above what people normally breathe.
Blood collection and mental tasks will be completed under room air conditions (21% oxygen concentration) and during oxygen breathing (fluctuating levels of 30% – 100% supplemental oxygen delivered by face mask.)
Measurements will include fNIRS, which involves wearing a head cap that uses infrared light to take measurements from the scalp.
Blood samples taken from a catheter placed in an artery in the wrist.
Exposure to barometric pressures in the hypobaric chamber that simulate sea level as well as altitudes of 8,000 ft. and 15,000 ft.
One additional 30 minute visit that takes place 2-3 days following the first visit, where a blood sample will be taken from a vein in the arm.
Who can participate: Healthy non-smoking adults who are 18-61 years old.
Who cannot participate: Persons who have a diagnosis of asthma requiring daily medications or sleep apnea; heart failure or diseases of the heart valves, a heart arrhythmia; seizure disorder or epilepsy; sickle cell anemia or sickle cell trait; bleeding disorders such as von Willebrand, hemophilia, thrombocytopenia; past history of brain or gastrointestinal bleeding. Persons who experience claustrophobia or who are currently pregnant or attempting pregnancy are also not eligible.