Decompression sickness

A hazard of divers and of others who work in or breathe compressed air or other gas mixtures. Decompression sickness is also called “the bends”, and it results from gas bubbles forming in the tissues and impeding the flow of blood. At depth, divers accumulate inert gas in their tissues from the high-pressure gas mixture that they breathe (see scuba-diving medicine). Problems can usually be avoided by allowing the excess gas in their tissues to escape slowly into the lungs during controlled, slow ascent or release of pressure. If ascent is too rapid and pressure falls too quickly, gas can no longer be held within a tissue. Resulting bubbles may block blood vessels, causing symptoms such as skin itching and mottling and severe pain in and around the larger joints. Symptoms of nervous system impairment (such as leg weakness or visual disturbances) are particularly serious, as is a painful, tight feeling across the chest. Divers with decompression sickness are immediately placed inside a recompression chamber. Pressure within the chamber is raised, causing the bubbles within the tissues to redissolve. Subsequently, the pressure in the chamber is slowly reduced, allowing the excess gas to escape safely via the lungs. If treated promptly, most divers with the “bends” make a full recovery. In serious, untreated cases, there may be long-term problems, such as paralysis.