Oxidative Stress Reaction to Hypobaric-Hyperoxic Civilian Flight Conditions.

Area of Science:

• Aerospace Medicine
• Environmental Physiology
• Biochemistry

Background:

• Military pilots face hyperoxic breathing and hypobaric environments, raising concerns about neuronal oxidative stress.
• The FAA recommends/mandates supplemental oxygen for civilian flights above 3048m/3657m, creating similar conditions.

Purpose of the Study:

• To investigate if hypobaric-hyperoxic flight conditions with supplemental oxygen cause significant oxidative stress in healthy individuals.
• To test the hypothesis using a flight simulation at 2500m and 4500m equivalent altitudes.

Main Methods:

• Twelve healthy subjects underwent a 3-hour flight simulation in a hypobaric chamber.
• Fraction of inspired oxygen (FiO2) levels increased (35-100%) at simulated altitudes of 2500m and 4500m.
• Oxidative stress markers malondialdehyde low-density lipoprotein (M-LDL) and glutathione-peroxidase 1 (GPX1) were measured via ELISA.

Main Results:

• Eleven subjects completed the study without adverse events.
• Oxygen partial pressure (PO2) increased with higher FiO2 levels.
• No significant increase in M-LDL or GPX1 was observed at 60% FiO2 at either altitude compared to baseline.

Conclusions:

• Supplemental oxygen up to 60% FiO2 during simulated flights at 2500m-4500m altitudes does not significantly increase serum oxidative stress markers.
• Individual responses varied, with a moderate correlation between age and glutathione peroxidase levels at 4500m.