10.16 Decompression Sickness

10.16.2 Define decompression sickness.

Decompression sickness, also known as “the bends”, occurs when dissolved gases, mainly nitrogen, form bubbles in the bloodstream and body tissues following a reduction in pressure.

These bubbles can cause a range of symptoms and complications.

10.16.4 Explain the causes of decompression sickness. 

Decompression sickness is caused when a reduction in surrounding pressure causes dissolved nitrogen to come out of solution and form bubbles in the blood and body tissues.

This may occur:

• after scuba diving, especially following a rapid ascent;
• when flying too soon after scuba diving, because the further reduction in pressure at altitude can trigger decompression sickness;
• during a climb to high altitude in an unpressurised aircraft; or
• following a rapid loss of cabin pressure.

During scuba diving, breathing compressed gas under increased pressure causes more nitrogen to dissolve into the body. If the diver ascends too quickly, the reduction in pressure may cause this nitrogen to form bubbles.