Decompression sickness (DCS; also known as divers' disease, the bends, aerobullosis, or caisson disease) describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurisation. DCS most commonly refers to problems arising from underwater diving decompression (i.e., during ascent), but may be experienced in other depressurisation events such as emerging from a caisson, flying in an unpressurised aircraft at high altitude, and extravehicular activity from spacecraft. DCS and arterial gas embolism are collectively referred to as decompression illness.
Since bubbles can form in or migrate to any part of the body, DCS can produce many symptoms, and its effects may vary from joint pain and rashes to paralysis and death. Individual susceptibility can vary from day to day, and different individuals under the same conditions may be affected differently or not at all. The classification of types of DCS by its symptoms has evolved since its original description over a hundred years ago. The severity of symptoms varies from barely noticeable to rapidly fatal.
Risk of DCS caused by diving can be managed through proper decompression procedures and contracting it is now uncommon. Its potential severity has driven much research to prevent it and divers almost universally use dive tables or dive computers to limit their exposure and to control their ascent speed. If DCS is suspected, it is treated by hyperbaric oxygen therapy in a recompression chamber. Diagnosis is confirmed by a positive response to the treatment. If treated early, there is a significantly higher chance of successful recovery.