There are two situations that endanger a diver’s life in a diving accident: decompression syndrome and aeroembolism, and both are often grouped together as a decompression accident.
Air is mainly composed of nitrogen and oxygen. And since the air under high pressure is compressed, each inspiration made in the depths contains many more molecules than an inspiration on the surface. The body constantly uses oxygen, so excess oxygen molecules inhaled under pressure do not accumulate. However, excess nitrogen does accumulate in the blood and tissues.
As the outside pressure decreases during the ascent after a dive, the accumulated nitrogen cannot be immediately released, thus forming bubbles in the bloodstream. These can expand and injure tissues or clog blood vessels – either directly or causing small clots – putting the diver’s life at risk.
In the hyperbaric chamber, OHB treatment is performed to restore normal blood circulation and the normal oxygen levels in the affected tissues. This treatment mainly has two effects:
- Increased pressure causes nitrogen bubbles to decrease in size and most to dissolve, making it easier to expel them from the body.
- Breathing only oxygen increases the nitrogen gradient between tissue and lung contents. By breathing only oxygen – and not air, which also contains nitrogen – in the body there is more concentration of nitrogen than outside, so osmosis expels excess nitrogen more quickly.
After recompression, the internal pressure of the chamber is gradually reduced with pre-set pauses, to allow time for excess gases to leave the body by breathing and no new nitrogen bubbles form.
Therefore, this therapy exerts several effects on the body that are useful for the treatment of diving accidents:
- Increasing oxygen concentration
- Decreased nitrogen concentration
- Decreased carbon monoxide concentration
- Decreasing the size of gas bubbles