Synonyms
Diver’s sickness, decompression accident or illness, caisson sickness (caisson sickness)Decompression sickness occurs most frequently in diving accidents and is therefore also called diver’s sickness. The real problem with decompression sickness is that if you ascend too quickly, gas bubbles form inside the body and these then trigger the typical symptoms. Decompression sickness is divided into three types according to the severity of the symptoms.
Definition
There are a few inconsistencies in the terminology. In English decompression sickness is called decompression sickness (DCS) or decompression illness. There is no difference between “sickness” and “illness”.
Many diving physicians do not accept this difference either. Another problem with the name is, to complete the confusion, that decompression sickness is also abbreviated as DCI (decompression incident). The umbrella term decompression sickness covers two different approaches to gas bubble formation inside the body.
On the one hand, the formation of gas bubbles can be caused by too much nitrogen in the blood or tissue (DCS). It can also be another gas, like helium or hydrogen. On the other hand, if the pressure is too high, it can lead to tears in the central pulmonary vessels and thus to the formation of air bubbles in the blood vessels (arterial gas bubble embolism, AEG).
Cause
The solubility of a gas in a liquid depends on the ambient pressure (Henry’s law). For example, when you dive to a depth of 30m, the partial pressure of the gas increases and therefore more gas dissolves in the blood. This means there is more dissolved nitrogen in the blood.
The blood now transports the nitrogen to the tissue, where more nitrogen accumulates due to the shifted pressure conditions (tissue saturation). The different tissues absorb nitrogen at different rates, depending on the blood flow rate. The stronger the blood supply to a tissue (e.g.
the brain), the faster it absorbs nitrogen, i.e. the tissue is saturated more quickly than in cartilage or bone, for example, where blood supply is poor. Similarly, desaturation takes place when the tissue emerges, i.e. the tissue releases the nitrogen back into the blood and the nitrogen is breathed out through the lungs, also varying from tissue to tissue. While the brain desaturates quite quickly, the bones or cartilage take a very long time.
When ascending, you must therefore observe the decompression rules, otherwise the external pressure drops faster than the tissues can desaturate if you ascend too quickly. The previously dissolved nitrogen and other gases no longer remain in solution and form gas bubbles in the blood and tissue fluid. This process can be compared to the foaming of a fizzy bottle when it is first opened.
The resulting gas bubbles can now cause mechanical injuries in the tissue and block blood vessels, similar to a thrombus (gas embolism). The danger of decompression sickness increases at high altitudes (mountain lake diving), as the atmospheric pressure is already lower here and the gases remain in solution even worse. The caisson disease was named after the caissons used to make foundations for bridge piers.
With the caissons it was possible to work for a longer period of time in contrast to the diving bells used before. With the introduction of the caissons, the number of decompression sicknesses increased. Astronauts also have an increased risk of decompression sickness when exiting space. To minimize the risk, astronauts must spend the night before space debarkation in a chamber where the pressure is significantly lower so that they can get used to the low pressure conditions.
