A new preoxygenation procedure for extravehicular activity (EVA)

Area of Science:

• Aerospace Medicine
• Human Physiology
• Space Exploration

Background:

• Standard protocols for extravehicular activity (EVA) require lengthy preoxygenation and staged-decompression schedules to mitigate decompression sickness (DCS) risk.
• Current methods involve hours of preoxygenation at ambient pressure followed by gradual pressure reduction.
• Optimizing these protocols is crucial for astronaut safety and mission efficiency.

Purpose of the Study:

• To investigate the efficacy of incorporating exercise during preoxygenation to reduce DCS risk.
• To evaluate alternative preoxygenation strategies that may shorten overall mission preparation time.
• To determine if exercise-enhanced preoxygenation can mitigate DCS at reduced pressure exposures.

Main Methods:

• A 10-minute exercise bout at 75% VO2peak was introduced during a 1-hour preoxygenation period.
• DCS risk was assessed following a 4-hour exposure at 4.3 psi.
• Control groups included 1-hour resting preoxygenation and 4-hour resting preoxygenation before the 4.3 psi exposure.

Main Results:

• A 1-hour preoxygenation with exercise followed by 4.3 psi exposure resulted in 42% DCS risk.
• A 4-hour resting preoxygenation without exercise followed by 4.3 psi exposure resulted in 47% DCS risk.
• The 1-hour preoxygenation with exercise and 4-hour preoxygenation without exercise showed no significant difference in DCS risk, but both were lower than previously reported resting protocols.

Conclusions:

• Exercise during preoxygenation is a viable strategy to reduce DCS risk.
• Incorporating exercise may allow for significant reductions in preoxygenation and/or staged-decompression time.
• This approach holds potential for streamlining EVA preparation, enhancing mission flexibility and safety.