Arterial gas embolism (AGE) is a condition which affects some divers. It is characterized by the appearance of bubbles in the blood which obstruct blood flow. As these bubbles travel through the body, they can cause damage to many major organs, including the brain. AGE is a serious form of decompression sickness, and in addition to appearing in divers, it can also emerge in people who have been subjected to rapid decompression, as for instance when the pressurization in an airplane cabin fails.
This condition is caused by the expansion of dissolved gases in the blood. These gases expand as pressure decreases. If the pressure is reduced slowly while the diver breathes normally, dissolved gases can dissipate out naturally. If, however, the pressure is reduced rapidly, the gases expand into bubbles, occluding blood flow. In some cases of arterial gas embolism, the patient also experiences pulmonary barotrauma, where the lungs literally explode because the dissolved gases are expanding so rapidly.
Some people refer to this condition as an “air embolism,” although it should more properly be known as a gas embolism, since it is caused by dissolved gases such as nitrogen, rather than literal air. If a gas bubble forms near the heart, the patient may rapidly go into distress, because his or her heart will not be able to pump blood. Gas bubbles can also reach the brain, impairing brain function and potentially causing brain damage.
Signs of an arterial gas embolism typically emerge within minutes of surfacing. A diver may complain of blurred vision or dizziness, and in extreme cases, a bloody froth will form around the mouth, and the diver will go into cardiac distress. Immediate first aid is required to stabilize the diver, and long-term treatment will be needed to treat the arterial gas embolism.
There are some steps which can be taken to prevent an arterial gas embolism. The risk is greatly increased if the diver has a lot of mucus in the lungs and throat, as for example in someone with a chest cold, because the mucus can trap air bubbles which will expand into an arterial gas embolism. People should not dive if they have colds, chest pains, and other respiratory problems. They should also make a habit of diving with buddies, and under the supervision of someone who is experienced with decompression sickness and arterial gas embolisms, so that the early signs can be recognized.