Return to Diving

Excerpt

Decompression illness is caused by bubbles that appear in the bloodstream or other tissues in the body by ascending too fast from underwater depth to the surface or from the surface to an altitude, such as in high-altitude fighter pilots. When ambient pressure increases, such as during diving, so will the pressure of any gas the person is breathing. This gas is distributed throughout the body at different speeds, where highly vascularized tissues equilibrate faster. Bubbles are formed when the ambient pressure is reduced faster than the ability of the blood or tissue to transport the gas, which is in solution (usually nitrogen), to the lungs to get exhaled. These bubbles can have various complex effects on the body, from blood and lymph flow obstruction to nerve injury by direct irritation or inflammatory mediators. These effects can be mild, resulting in pain or paresthesias, or severe, leading to paralysis and death.

The most widely used classifications of decompression illness include decompression sickness type 1 (DCS1) with mild pain or mild skin symptoms, decompression sickness type 2 (DCS2) with neurological involvement, and arterial gas embolism, resulting from pulmonary barotrauma. The primary treatment of decompression illness is recompression in a hyperbaric chamber, which will increase the ambient pressure again, reduce the speed of new bubble formation and existing bubble size, and create a large diffusion gradient for the offending gas by breathing 100% oxygen. The appropriate treatment of decompression illness is usually very effective, especially if began early after the injury, leaving either minimal or no residual effects. As the body tries to heal, most residual effects will improve even further with time. However, some residual effects may be permanent. In addition, a diver may also suffer from barotrauma to air-filled spaces such as ears, sinuses, and lungs during a dive.

After an episode of decompression illness or other diving-related injuries, many divers want to go diving again, either for recreation, work, or military service. A thorough understanding of the factors that led to the injury and a careful clinical exam will help the diving medicine specialist decide if additional tests are indicated and advise the diver of his future risk with a return to diving. Guidelines do exist for military, government, scientific, and commercial divers. However, no guidelines have been published in the United States for recreational divers, dive masters, or dive instructors.