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Ebullism

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Ebullism is the formation of water vapour bubbles in bodily fluids due to reduced environmental pressure, for example at high altitude. It occurs because a system of liquid and gas at equilibrium will see a net conversion of liquid to gas as pressure lowers; for example, liquids reach their boiling points at lower temperatures when the pressure on them is lowered.[1] The injuries and disorder caused by ebullism is also known as ebullism syndrome.[2] Ebullism will expand the volume of the tissues, but the vapour pressure of water at temperatures in which a human can survive is not sufficient to rupture skin or most other tissues encased in skin.[3]

Symptoms

Symptoms of ebullism include bubbles in the membranes of the mouth and eyes, swelling of the soft tissues with possible bruising, and bubbles in the blood. Blood circulation and breathing may be impaired or stopped by cardiac vapourlock. The brain tissue may be starved of oxygen because of blockage of arteries resulting in rapid loss of consciousness, and the lungs may swell and hemorrhage. Death results unless recompression is rapid enough to reduce the bubbles before excessive tissue damage occurs.[4][3] Head exposure may result in freezing of the corneal surface of the eye, impairing vision.[5]

Mechanism

In the atmospheric pressure present at sea level, water boils at 100 °C (212 °F). At an altitude of 63,000 feet (19,000 m), it boils at only 37 °C (99 °F), the normal body temperature of humans. This altitude is known as Armstrong's Line.[6] Ebullism occurs when unprotected humans are exposed to altitudes above the Armstrong limit where the vapor pressure of tissues is less than the ambient pressure.[5] In practice bodily fluids do not boil off continuously at this altitude because the skin and outer organs have enough strength to withstand the internal pressure,[7] so the pressure inside the tissues would increase to match vapour pressure. Nitrogen dissolved in the tissues may also accumulate in the vapour bubbles causing altitude decompression sickness. The pathophysiology of ebullism was studied in the 1940s to 1960s on animals.[5]

Treatment

Little information is available on the effectiveness of conventional treatment, such as hyperbaric oxygen, or adjunctive therapies, for injuries due to ebullism.[5] Spontaneous recovery has occurred in the few cases where recompression was applied with minimal delay, or the damage was restricted to parts of the limbs. Other examples were fatal.[8]

Prevention

To prevent ebullism, the tissues must be kept under sufficient pressure that vaporisation of the aqueous constituents is not possible in the range of temperature those tissues may experience.[1]

Epidemiology

Ebullism risk is associated with spaceflight, particularly EVA accidents, rapid decompression of aircraft at very high altitudes, and pressure suit failure during flight and training exercises.[5]

In 1960, Joseph Kittinger experienced localised ebullism during a 31 kilometres (19 mi) ascent in a helium-supported gondola.[9] His right-hand glove failed to pressurise and his hand expanded to roughly twice its normal volume[10][11] accompanied by disabling pain. His hand took about three hours to recover after his return to the ground.

Tissue samples from the remains of the crew of Space Shuttle STS-107 Columbia revealed evidence of ebullism. Given the level of tissue damage, the crew could not have regained consciousness even with re-pressurization.[8]

Etymology

The term "space ebullism" was introduced by Captain Julian E. Ward in his paper "The True Nature of the Boiling of Body Fluids in Space", published in Aviation Medicine in October 1956.[12][13] It was suggested "because the word ebullism does not connote the addition of heat to produce vapor." It comes from the Latin ebullire, meaning "to bubble out, or to boil up."

See also

References

  1. ^ a b Murray, Daniel H.; Pilmanis, Andrew A.; Blue, Rebecca S.; Pattarini, James M; Law, Jennifer; Bayne, C Gresham; Turney, Matthew W; Clark, Jonathan B (2013). "Pathophysiology, prevention, and treatment of ebullism". Aviation, Space, and Environmental Medicine. 84 (2): 89–96. doi:10.3357/ASEM.3468.2013. PMID 23447845.
  2. ^ Norfleet, W.T. (2008). "Decompression-Related Disorders: Decompression Sickness, Arterial Gas Embolism, and Ebullism Syndrome". In Barratt, M.R.; Pool, S.L. (eds.). Principles of Clinical Medicine for Space Flight. Springer, New York, NY. pp. 223–246. doi:10.1007/978-0-387-68164-1_11. ISBN 978-0-387-98842-9.
  3. ^ a b Springel, Mark (30 July 2013). "The human body in space: Distinguishing fact from fiction". Harvard University Graduate School of Arts and Sciences. Archived from the original on 7 June 2023. Retrieved 6 October 2023.
  4. ^ Czarnik, Tam. "Ebullism at 1 Million Feet". Archived from the original on 2018-10-18. Retrieved 2010-02-16.
  5. ^ a b c d e Stegmann, Barbara J.; Pilmanis, Andrew A.; Derion, Toniann (1 February 1992). Improving survival after tissue vaporization (Ebullism). 5th Annual Workshop on Space Operations Applications and Research (SOAR 1991), Volume 2. NASA. Johnson Space Center. 19920013110.
  6. ^ Davis, Jeffrey R., Johnson, Robert, and Stepanek,Jan, Fundamentals of Aerospace Medicine, 4th Edition (2008), p. 252.
  7. ^ Landis, Geoffrey A., "Human Exposure to Vacuum Archived July 21, 2009, at the Wayback Machine" (Retrieved 2010-02-16).
  8. ^ a b National Aeronautics and Space Administration (2008). "Columbia Crew Survival Investigation Report NASA/SP-2008-565" (PDF). Lyndon B. Johnson Space Center, Houston, Texas. pp. 3–83. Archived (PDF) from the original on 2019-12-21. Retrieved 2021-03-11.
  9. ^ Pilmanis, Andrew; William Sears (December 2003). "Physiological hazards of flight at high altitude". The Lancet. 362: s16–s17. doi:10.1016/S0140-6736(03)15059-3. PMID 14698113. S2CID 8210206. Archived from the original on 2021-05-27. Retrieved 2019-09-10.
  10. ^ Higgins, Matt (May 24, 2008). "20-Year Journey for 15-Minute Fall". The New York Times (online). p. 2. Archived from the original on 2021-08-29. Retrieved 2012-09-23.
  11. ^ "Skydive from the Stratosphere" Archived 2021-08-29 at the Wayback Machine, NOVA Online, Public Broadcasting Service(PBS). November 2000. Retrieved 2012-09-23
  12. ^ Mohler, Stanley R.; Day, Pamela C. (September 2006). "The Annual Awards of the Aerospace Medical Association". Aviation, Space, and Environmental Medicine. 77 (9): 979. Archived from the original on 2014-08-29. Retrieved 2018-12-29.
  13. ^ Ward, Julian E. (1956). "The True Nature of the Boiling of Body Fluids in Space". The Journal of Aviation Medicine. 27 (5). Aviation Medicine: 429–39. PMID 13366883. S2CID 6765165.