What Is It?
Decompression sickness, also called generalized barotrauma or the bends, refers to injuries caused by a rapid decrease in the pressure that surrounds you, of either air or water. It occurs most commonly in scuba or deep-sea divers, although it also can occur during high-altitude or unpressurized air travel. However, decompression sickness is rare in pressurized aircraft, such as those used for commercial flights.
When you scuba dive with compressed air, you take in extra oxygen and nitrogen. Your body uses the oxygen, but the nitrogen is dissolved into your blood, where it remains during your dive. As you swim back toward the surface after a deep dive, the water pressure around you decreases.