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What are the bends?


The term 'the bends' is commonly applied to decompression sickness in which gases, chiefly nitrogen, in the bloodstream accumulate under pressure and expand into bubbles if the pressure is lowered too rapidly. The process is similar to the one that occurs when a bottle of carbonated soft drink or wine is opened. These gas bubbles impair the normal movement of limbs by lodging in the joints and surrounding tissue, so cutting off the blood supply to nerve endings. Pain is often extremely severe and may prevent the victim from straightening the affected limbs, which thus remain bent.

Permanent damage may be caused to the bursas or fluid sacs in the joints and untreated serious cases may result in death.

Skindivers working with a scuba (an acronym of 'self contained underwater breathing apparatus') or an air supply pumped from the surface are the most common victims of the bends as they are breathing gases under pressure. Such divers must observe safety procedures while rising to the surface after a dive and detailed decompression tables exist for this purpose. Tunnel workers may also suffer the bends if brought too rapidly from pressurized shafts. Treatment for the bends requires the victim to be recompressed, either in a special chamber or by returning to a pressurized situation, and then slowly decompressed to allow the gases in the bloodstream to be dissipated safely.

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