Ebullism

Ebullism is the formation of water vapour bubbles in bodily fluids due to reduced environmental pressure, usually at extreme 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. The injuries and disorder caused by ebullism is also known as ebullism syndrome. 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. Ebullism produces predictable injuries, which may be survivable if treated soon enough, and is often accompanied by complications caused by rapid decompression, such as decompression sickness and a variety of barotrauma injuries. Persons at risk are astronauts and high altitude aviators, for whom it is an occupational hazard.

==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 vapour lock. 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 restore oxygenation and reduce the bubbles before excessive tissue damage occurs. Head exposure may result in freezing of the corneal surface of the eye, impairing vision. Other signs and symptoms of rapid decompression injury may also be present.