Editing Decompression illness (section)

== Classification ==
DCI can be caused by two different mechanisms, which result in overlapping sets of symptoms. The two mechanisms are:
* [[Decompression sickness]] (DCS), which results from metabolically inert gas dissolved in body tissue under pressure emerging out of solution and forming bubbles during decompression. It typically afflicts underwater divers on poorly managed ascent from depth or aviators flying in inadequately pressurised aircraft.
* [[Arterial gas embolism]] (AGE), which is perfusion blockage caused by gas bubbles in the arterial bloodstream. In the context of DCI these may form either as a result of bubble nucleation and growth by dissolved gas into the blood on depressurisation, which is a subset of DCS above, and leakage from venous circulation to arterial circulation via [[patent foramen ovale]] or other shunt, or by gas entering the blood mechanically as a result of pulmonary [[barotrauma]]. Pulmonary barotrauma is a rupturing of lung tissue by expansion of [[breathing gas]] held in the lungs during depressurisation. This may typically be caused by an [[Underwater diving|underwater diver]] ascending while holding the breath after breathing at ambient pressure, ambient pressure escape from a submerged submarine without adequate exhalation during the ascent, or the explosive decompression of an aircraft cabin or other pressurised environment. Other forms of lung overpressure injury such as [[pneumothorax]] require distinctly different treatment to AGE.

In any situation that could cause decompression sickness, there is also potentially a risk of [[Air embolism|arterial gas embolism]], and as many of the symptoms are common to both conditions, it may be difficult to distinguish between the two in the field, and first aid treatment is the same for both mechanisms.<ref name="Cronje 2014" />