Decompression Sickness

What Is It?

Decompression sickness, also called generalized barotrauma or the bends, refers to injuries brought about by a rapid decrease in the pressure that surrounds you, the pressure 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 quantities of oxygen and nitrogen. The oxygen is used by your body, but the nitrogen is dissolved into your blood, where it remains during your dive. As you swim toward the surface from a deep dive, the water pressure around you decreases. If this transition occurs too quickly, the nitrogen does not have time to clear from your blood. Instead, it separates out of your blood and forms bubbles in your tissues or blood. The nitrogen bubbles cause decompression sickness. The condition commonly is called the bends because joint pain is a common symptom.

What happens inside your body during decompression sickness is just like what happens when you open a carbonated beverage. When you open the beverage, you decrease the pressure surrounding the beverage in the container, which causes the gas to come out of the liquid in the form of bubbles. If nitrogen bubbles form in your blood, they can damage blood vessels and block normal blood flow.

Factors that put you at higher risk of decompression sickness include:

• Being older than 30
• Being female
• Low cardiovascular fitness
• High body-fat percentage
• Use of alcohol or tobacco
• Fatigue, seasickness or lack of sleep
• Injuries (old or current)
• Diving in cold water

If you have severe asthma or another lung disease, you should discuss diving safety with a physician. People with longstanding asthma may have developed thin-walled air pockets in the lungs called bullae that do not empty quickly when a breath is exhaled. As you are returning to the surface after a deep dive, air in the bullae may expand. If a bulla ruptures, it can cause a collapsed lung or allow a relatively large air bubble (called an air embolism) to reach your central circulation system. An air embolism can result in a stroke. Although there are few examples of this complication, caution is advisable.

Symptoms

Symptoms of decompression sickness include:

• Joint pain
• Dizziness
• Extreme fatigue
• Tingling or numbness
• Weakness in arms or legs
• A skin rash