List of signs and symptoms of diving disorders

Diving disorders are medical conditions specifically arising from underwater diving. The signs and symptoms of these may present during a dive, on surfacing, or up to several hours after a dive.

The principal conditions are decompression illness (which covers decompression sickness and arterial gas embolism), nitrogen narcosis, high pressure nervous syndrome, oxygen toxicity, and pulmonary barotrauma (burst lung). Although some of these may occur in other settings, they are of particular concern during diving activities.^[1]

The disorders are caused by breathing gas at the high pressures encountered at depth, and divers will often breathe a gas mixture different from air to mitigate these effects. Nitrox, which contains more oxygen and less nitrogen, is commonly used as a breathing gas to reduce the risk of decompression sickness at recreational depths (up to about 40 metres (130 ft)). Helium may be added to reduce the amount of nitrogen and oxygen in the gas mixture when diving deeper, to reduce the effects of narcosis and to avoid the risk of oxygen toxicity. This is complicated at depths beyond about 150 metres (500 ft), because a helium–oxygen mixture (heliox) then causes high pressure nervous syndrome.^[1] More exotic mixtures such as hydreliox, a hydrogen–helium–oxygen mixture, are used at extreme depths to counteract this.^[2]