Self-Contained Underwater Breathing Apparatus (SCUBA) diving is a recreational sport that has gained wide popularity over the last 20 years. Although the sport is associated with certain medical problems, serious conditions are uncommon in divers. A beginning diver must gain as much knowledge as possible about how to scuba dive safely. Even an experienced diver needs to know the limits of his or her experience and training to avoid serious or life-threatening injuries.

About Scuba Diving

Recreational scuba diving is a pleasurable activity that involves diving to a maximum depth of 130 feet. Divers breathe through a mouthpiece attached to a tank of compressed air while underwater. A regulator ensures a diver receives air at the correct pressure to counteract the effect of surrounding, much higher, water pressure. Scuba-certifying agencies offer classroom training and practical instruction to people interested in becoming divers; classes take place in pools or open water.

Among millions of recreational divers worldwide, only about 90 deaths are reported annually. Fewer than about 1000 divers suffer severe dive-related health problems and require recompression therapy – a type of therapy that puts a diver in a chamber for several hours while breathing 100 percent oxygen in order to increase blood-oxygen concentration and decrease concentration of nitrogen and carbon dioxide.

Middle-ear squeezes are the most common medical problem scuba divers encounter. The pain in the middle ear is due to a difference in pressure between the air inside the ears or mask and the surrounding water pressure, which increases as a diver goes down. The inner ear and sinuses are less commonly affected. Scuba divers are also prone to injuries such as cuts and scrapes on arms and legs when they come into contact with fish and other marine animals. Other underwater objects including certain species of coral, exposed sharp metal from shipwrecks, and fishing lines may also cause injury.

There may also be some minor joint pain (colloquially known as “the niggles”) that should reside after 10 minutes. If pain does not go away it could be a sign of a more serious condition.

Severe Medical Problems

The most serious medical problems that affect scuba divers include inner-ear barotrauma, pulmonary barotrauma, arterial gas embolism, or decompression sickness during or after a dive.

Barotraumas happen while rising to the surface of the water when gas inside the body expands and hurts the surrounding body tissue. Inner-ear barotrauma is characterized by severe dizziness and hearing loss. This condition happens when a diver's ear pressure fails to equalize with the pressure of the water.

In pulmonary barotraumas a diver experiences chest pain, shortness of breath, and voice hoarseness. For some, this condition may be bad enough to collapse the lung. This can result from improper breathing while ascending to the water’s surface or if the diver is suffering from a preexisting respiratory-tract infection.

An arterial gas embolism is a type of barotraumas where air bubbles are released into a diver's blood stream. This is a serious diving injury characterized by numbness or tingling in the skin, weakness, paralysis, or loss of consciousness. If the air bubbles travel to the brain they could cause a stroke.

Decompression sickness, sometimes called "the bends," occurs during ascent to the water surface. Bubbles form in the blood because inert nitrogen gas that is normally dissolved in body tissue and blood instead releases into the blood stream. These bubbles can cause injury to body tissue and block blood vessels. A common early sign of the bends is joint pain that lasts longer than 10 minutes. Complications include spinal cord, brain, and lung dysfunction.

Scuba divers should seek immediate medical care if they develop any of these conditions.

All divers, especially beginners, should be conscious of diving within the limits of their experience and training level to avoid dive-related injuries or death. A diver should regularly undergo a thorough physical examination by his or her doctor, especially if the diver is overweight, smokes, undergoes surgery close to a dive, or is taking medications for any illness. Before diving, a diver must avoid alcohol and medications (unless deemed safe by a doctor).

It is always better to dive with a buddy. Making a plan for a dive is always advised. All equipment should be verified to be in proper working condition before leaving the boat.

Air supply must be closely monitored during each dive. A diver should not attempt a dive in which he or she feels uncomfortable. The diver must be familiar with the underwater area and its dangers, including local tides and currents. He or she should equalize the pressure in his or her ears and mask smoothly by adjusting the air-tank regulator gradually. Divers should avoid diving beyond the parameters of the dive tables and the dive computer, which will help them avoid decompression sickness.

Should an issue arise, it is very important for a diver to not panic underwater, relax and think the problem through. Seek help from a diving partner if you feel confused or afraid at any point during a dive.

A diver should always ascend slowly, while breathing normally and avoiding holding his or her breath. A diver should seek medical care immediately if he or she does not feel good or feels pain after diving. It is recommended for divers to avoid flying for 12 hours after a no-decompression dive, even in a pressurized airplane. If the dive required decompression stops, the diver should avoid flying for at least 24 hours. These precautions are advised because air pressure in the airplane is very different from that underwater, and switching from one to the other quickly increases a diver's chance of developing decompression sickness.

A hyperbaric chamber is a facility into which a diver may be placed to reduce diving-related sickness.

The chamber places the diver under increased air pressure, which shrinks the gas bubbles in his or her blood and allows them to pass smoothly through his or her blood vessels.

This can help reduce illness in a person who already has arterial gas embolism or decompression sickness.

The Divers Alert Network (DAN), located at Duke University Medical Center in Durham, N.C., has emergency medical technicians and nurses on-call 24 hours to answer any queries regarding emergency or non-emergency diving-related health problems.

The EMTs can also help direct a diver to his or her nearest hyperbaric chamber or other appropriate medical facility. Emergency and non-emergency telephone numbers at DAN are 919-684-4326 and 800-326-3822, respectively.

Scuba diving can be dangerous sport if precautions are not taken. Worldwide, most scuba-diving accidents that result in death or debilitating injuries are attributed to human error.