Dynamic lung behavior under high G acceleration monitored with electrical impedance tomography.

Area of Science:

• Aerospace Medicine
• Physiology
• Medical Imaging

Background:

• Astronauts face high G-acceleration during spaceflight, potentially causing hypoxemia.
• Lung ventilation and gas exchange are affected by gravitational forces.
• Electrical impedance tomography (EIT) can monitor lung air distribution.

Purpose of the Study:

• To investigate the effects of high G-acceleration on lung ventilation and gas exchange.
• To assess the utility of EIT in monitoring these changes during simulated spaceflight.
• To understand the mechanisms of hypoxemia induced by G-forces.

Main Methods:

• Ten participants were exposed to +2, +4, and +6 G (chest-to-back) in a long-arm centrifuge.
• Participants were in a supine position during acceleration.
• EIT was used to monitor dynamic changes in lung ventilation distribution.

Main Results:

• Dorsal lung regions emptied faster than ventral regions.
• Ventilation shifted from dorsal to ventral areas.
• Alveolar pressure changes led to upper airway collapse and ventral gas trapping, restricting gas exchange.

Conclusions:

• High G-acceleration significantly alters lung ventilation distribution.
• Ventral gas trapping and restricted gas exchange were observed at +6 G.
• Individual responses varied at +4 G, but effects were pronounced and similar at +6 G.