What is Decompression Sickness?

Decompression sickness is a medical condition which manifests in people who have undergone rapid decompression. It most classically affects divers who ascend to the surface too quickly, although decompression sickness can also happen when a pressurized aircraft loses pressure, or when someone exits a pressurized environment like a caisson or a mine. Decompression sickness is also referred to as DCS, decompression illness, the bends, diver's sickness, or caisson sickness.

This condition is caused by the body's response to pressure. As the pressure around a body increases, the levels of dissolved gases in the blood increase. When the pressure decreases rapidly, these dissolved gases turn into bubbles, rather than dissipating naturally through the lungs. These bubbles cause a variety of health problems. Since nitrogen is the most abundant dissolved gas, the bubbles involved in decompression sickness are typically nitrogen bubbles.

When people dive to certain depths, they have to undergo decompression before they are allowed to surface. In decompression, the body is given a chance to acclimate to the change in pressure when a diver either makes a series of decompression stops in the water, or sits in a pressurized chamber known as a hyperbaric chamber and the pressure is slowly decreased over a period of minutes or hours. Hyperbaric chambers are also used in treatment of decompression sickness: sometimes the best treatment is recompression followed by a slow decompression. Special gas mixtures are also used for deep water dives to reduce the risk of developing DCS.

The symptoms associated with DCS include joint pain, itching, chest pain, cramps, skin irritation, and neurological symptoms like confusion or even paralysis. Sometimes the symptoms are mild, and a diver may not be aware that he or she has developed decompression sickness, leading some divers to joke that denial is another common symptom. Diving with a buddy and under the supervision of someone who is experienced with decompression sickness is a good idea, as it ensures that someone will intervene quickly if decompression sickness manifests.

This condition can cause long-lasting physical and neurological problems ranging from incontinence to partial paralysis if it is not addressed. In some cases, it can even be fatal. Fortunately, rates of decompression sickness have radically decreased since the condition was first identified and understood, and the incidence rate is very low. The condition is most common among inexperienced divers and divers who experience emergencies which force them to surface in less than ideal conditions.