Cabin Pressure Altitude Effect on Acceleration Atelectasis After Agile Flight Breathing 60% Oxygen

Area of Science:

• Aerospace Medicine
• Pulmonary Physiology
• Aviation Toxicology

Background:

• High-performance aircraft maneuvers can induce physiological stress in pilots.
• Contemporary pilot flight equipment involves breathing supplemental oxygen, often at concentrations like 60% oxygen.

Purpose of the Study:

• To determine if breathing 60% oxygen during high-G flight maneuvers causes atelectasis.
• To investigate the influence of cabin pressure altitude on the extent of atelectasis.

Main Methods:

• A flight trial involving 14 male aircrew flying in a Hawk T Mk1 aircraft.
• Sorties included 16 maneuvers at +5 Gz, with participants breathing 60% oxygen at High (14,500-18,000 ft) and Low (4000-6000 ft) cabin altitudes.
• Measurements included lung volumes (spirometry), basal lung volume (EIT), and peripheral oxygen saturation (pulmonary shunt fraction) pre- and post-flight.

Main Results:

• Forced inspiratory vital capacity (FIVC) significantly decreased post-flight in both High and Low cabin altitudes, indicating reduced lung volume.
• Electrical impedance tomography (EIT) measures also showed decreased FIVC, suggesting persisting airway closure.
• Peripheral oxygen saturation (SpO2) was lower post-flight, with an estimated pulmonary shunt fraction of up to 5.7%.

Conclusions:

• Breathing 60% oxygen during high-G flight maneuvers leads to a modest reduction in lung volume and blood oxygenation.
• Cabin pressure altitude had no significant influence on the observed physiological changes.
• The operational impact of these findings on pilot performance is likely minimal.