Decompression sickness (DCS) or “the bends” occurs when injuries are caused by a rapid decrease in atmospheric pressure of water or air. DCS is most commonly associated with scuba diving however it can also occur when astronauts return to the earths surface and hikers descend a high altitude too quickly.
DCS causes gas bubbles (typically Nitrogen) to form in the bodily tissue or blood. This occurs when the external pressure changes too fast for the body to acclimatize, which does not allow nitrogen to properly clear from the blood. It is nicknamed “the bends” because of the extreme joint pain associated with the condition.