Ebullism
Encyclopedia
Ebullism is the formation of gas
bubble
s 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 point at lower temperatures when the pressure on them is lowered.
, water boils at 100°C (212°F). At an altitude of 63,000 feet (18,900 m), it boils at only 37°C (98.6°F), the normal body temperature of humans. This altitude is known as Armstrong's Line
. In practice bodily fluids do not boil off at this altitude. This is because the skin and outer organs have enough strength to withstand this pressure, thus pressure inside the body would be significantly higher—however, bubbles starting to form is still an issue.
Symptoms of ebullism include bubbles in the membranes of the mouth and eyes, swelling of the skin
, and bubbles in the blood. Blood circulation and breathing may be impaired or stopped. The brain
tissue may be starved
of oxygen
because of blockage of arteries
, and the lungs may swell and hemorrhage. Death results unless recompression is rapid enough to reduce the bubbles before tissue damage occurs.
To prevent ebullism, a pure oxygen (O2) atmosphere was used in early space flights to eliminate nitrogen in the blood. However other risks associated with using pure O2 as a breathing gas caused its abrupt termination by NASA
after the death of three astronauts in a fire resulting from its use on Apollo 1
. Russian cosmonauts used pure oxygen before changing to a higher-pressure nitrox mixture, leading to incompatibility problems in 1975 on the Apollo-Soyuz Test Project. There has been some speculation as to the effectiveness of using techniques to lower body temperature however this is rarely used due to detrimental effects on the subject. Space suits are often pressurized to several psi
lower than stations' capsules or shuttles and since they still use pure O2, an acclimation period is common in the airlock to remove nitrogen and other gases from the bloodstream.
Gas
Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...
bubble
Liquid bubble
A bubble is a globule of one substance in another, usually gas in a liquid.Due to the Marangoni effect, bubbles may remain intact when they reach the surface of the immersive substance.-Common examples:...
s in bodily fluids due to reduced environmental pressure, for example at high altitude
Altitude
Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
. 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 point at lower temperatures when the pressure on them is lowered.
Description
In the atmospheric pressure present at sea levelSea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
, water boils at 100°C (212°F). At an altitude of 63,000 feet (18,900 m), it boils at only 37°C (98.6°F), the normal body temperature of humans. This altitude is known as Armstrong's Line
Armstrong Limit
The Armstrong limit, often called Armstrong's line, is the altitude that produces an atmospheric pressure so low that water boils at the normal temperature of the human body: 37 °C . It is named after Harry George Armstrong, who founded the U.S. Air Force’s Department of Space Medicine in...
. In practice bodily fluids do not boil off at this altitude. This is because the skin and outer organs have enough strength to withstand this pressure, thus pressure inside the body would be significantly higher—however, bubbles starting to form is still an issue.
Symptoms of ebullism include bubbles in the membranes of the mouth and eyes, swelling of the skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
, and bubbles in the blood. Blood circulation and breathing may be impaired or stopped. The brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
tissue may be starved
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
of oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
because of blockage of arteries
Artery
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....
, and the lungs may swell and hemorrhage. Death results unless recompression is rapid enough to reduce the bubbles before tissue damage occurs.
To prevent ebullism, a pure oxygen (O2) atmosphere was used in early space flights to eliminate nitrogen in the blood. However other risks associated with using pure O2 as a breathing gas caused its abrupt termination by NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
after the death of three astronauts in a fire resulting from its use on Apollo 1
Apollo 1
Apollo 1 was scheduled to be the first manned mission of the Apollo manned lunar landing program, with a target launch date of February 21, 1967. A cabin fire during a launch pad test on January 27 at Launch Pad 34 at Cape Canaveral killed all three crew members: Command Pilot Virgil "Gus"...
. Russian cosmonauts used pure oxygen before changing to a higher-pressure nitrox mixture, leading to incompatibility problems in 1975 on the Apollo-Soyuz Test Project. There has been some speculation as to the effectiveness of using techniques to lower body temperature however this is rarely used due to detrimental effects on the subject. Space suits are often pressurized to several psi
Pounds per square inch
The pound per square inch or, more accurately, pound-force per square inch is a unit of pressure or of stress based on avoirdupois units...
lower than stations' capsules or shuttles and since they still use pure O2, an acclimation period is common in the airlock to remove nitrogen and other gases from the bloodstream.