When diving, nitrogen is absorbed into the body. After surfacing, nitrogen is released during respiration (called off-gassing). This is a normal process, but if a large amount of nitrogen is absorbed and then the diver surfaces too quickly, the excess nitrogen forms bubbles in the body. Once these bubbles enter the bloodstream, the disruptions they cause are called decompression sickness (DCS).

A Body Filled With Bubbles

■Symptoms of DCS:

As nitrogen absorption varies in the different areas of the body, there are distinct types of DCS – type I (mild); type II (serious) and type III (with Arterial Gas Embolization, or AGE).

Type I is marked by dermopathy such as skin rashes, itchiness, and the like, as well as joint pain (aka “The Bends”). Upper body joint pain is more prevalent, ranging from a dull ache to sharp needle-like pain. Type I DCS accounts for roughly 90% of cases. Less common is type II DCS, with pulmonary symptoms, hypovolemic shock, or nervous system involvement. Type II can leave residual complications, and may lead to death in the worst case scenario.

Undiagnosed, DCS can lead to things such as chronic joint pain and osteonecrosis.

■Decompression Sickness Emergency Care and Prevention

For emergency care, oxygen therapy (100% at 10-15L/min) and immediate transport to a hospital with recompression chamber is key. Prevention includes allowing your body to off-gas as much absorbed nitrogen as possible by slowly ascending from all dives, especially for deep and long dives. Use of dive computers is beneficial as they are programmed to give water depth, dive time, and other data which help you to prevent DCS.

Further, they warn against rates of ascent that are too fast.