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Decompression sickness and intravenous bubble formation using a 7.8 psia simulated pressure-suit environment
Aviation, Space, and Environmental Medicine
|March 1, 1986
Summary
This study found that 7.8 psia spacesuit pressure is insufficient to prevent decompression sickness (DCS) in a 50% oxygen/nitrogen environment during simulated extravehicular activities (EVAs). Further research is needed to determine the minimum safe pressure.
Area of Science:
- Aerospace Medicine
- Human Physiology
- Space Exploration Safety
Background:
- Decompression sickness (DCS) is a risk during space missions.
- Understanding minimum spacesuit pressure is crucial for astronaut safety.
- Previous research has not definitively established safe pressure limits for mixed gas environments.
Purpose of the Study:
- To determine the minimum spacesuit pressure required to prevent DCS.
- To evaluate DCS risk in a 50% oxygen/50% nitrogen atmosphere.
- To assess the impact of exercise during simulated extravehicular activities (EVAs).
Main Methods:
- 30 male volunteers participated in 3-day EVA simulations.
- Exposure to 7.8 psia (5,031 m altitude equivalent) with a 50% O2/50% N2 mix.
- Continuous 6-hour exposures with simulated EVA exercise workloads.
- Precordial Doppler monitoring for intravenous gas bubbles.
Main Results:
- 73.3% of subjects exhibited intravenous bubbling on at least one day.
- 26.7% of subjects remained bubble-free throughout the study.
- One case of DCS occurred, indicating 7.8 psia is not sufficient.
- No correlation found between body fat or age and bubble incidence.
Conclusions:
- 7.8 psia in a 50% O2/50% N2 environment is not adequate to prevent DCS during EVA simulations.
- Astronaut safety requires a higher minimum spacesuit pressure than tested.
- Further studies are necessary to identify the precise safe pressure threshold.