Decompression sickness Decompression sickness 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 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
Scuba diving can be used, usually helium, when the resultant three gas mixture is called trimix, and when the nitrogen is fully substituted by helium, heliox. For dives requiring long decompression stops, divers may carry cylinders containing different gas mixtures for the various phases of the dive, typically designated as Travel, Bottom, and Decompression gases. These different gas mixtures may be used to extend bottom time, reduce inert gas narcotic effects, and reduce decompression times. To take advantage of the freedom of movement afforded by scuba equipment, the diver needs to be mobile underwater. Personal mobility is enhanced by swimfins and optionally