(See also Overview of Diving Injuries Overview of Diving Injuries People who engage in deep-sea or scuba diving are at risk of a number of injuries, most of which are caused by changes in pressure. These disorders also can affect people who work in underwater... read more .)
Air bubbles can enter arterial or venous blood (air embolism—see Unusual Types of Emboli Unusual types of emboli Pulmonary embolism is the blocking of an artery of the lung (pulmonary artery) by a collection of solid material brought through the bloodstream (embolus)—usually a blood clot (thrombus) or... read more ) after pulmonary (lung) barotrauma Pulmonary barotrauma Barotrauma is tissue injury caused by a change in pressure, which compresses or expands gas contained in various body structures. The lungs, gastrointestinal tract, part of the face covered... read more or decompression sickness Decompression Sickness Decompression sickness is a disorder in which nitrogen dissolved in the blood and tissues by high pressure forms bubbles as pressure decreases. Symptoms can include fatigue and pain in muscles... read more . When bubbles occur in arteries, they may travel to any organ in the body and block small blood vessels, most commonly those of the brain, but also of the heart, skin, and kidneys. A very large air embolism can block flow in the heart chambers or the large arteries. When bubbles occur in veins, they may pass into the arteries through heart defects such as a patent foramen ovale or atrial septal defect Atrial and Ventricular Septal Defects Atrial and ventricular septal defects are holes in the walls (septa) that separate the heart into the left and right sides. Holes can be present in the walls of the heart between the upper heart... read more .
Arterial gas embolism (sometimes referred to as AGE in the diving literature) is a leading cause of death among divers.
Symptoms of arterial gas embolism usually appear within a few minutes of reaching the surface. Arterial gas embolism to the brain often resembles a stroke, resulting in confusion and partial paralysis or loss of sensation. Some people have sudden loss of consciousness or seizures. Severe arterial gas embolism can lead to shock Shock Shock is a life-threatening condition in which blood flow to the organs is low, decreasing delivery of oxygen and thus causing organ damage and sometimes death. Blood pressure is usually low... read more and death.
Other symptoms may result from an underlying pulmonary barotrauma or decompression sickness, or from arterial gas embolism in any of the following:
Divers who lose consciousness during ascent or very shortly afterward are assumed to have arterial gas embolism. They must be treated promptly. Imaging tests are sometimes done but are not always reliable.
People with arterial gas embolism are immediately made to lie down and given oxygen. They must be returned as soon as possible to a high-pressure environment, so that the air bubbles are compressed and forced to dissolve in the blood. Many medical centers have high-pressure (recompression or hyperbaric) chambers for this purpose.
Flying, even at a low altitude, reduces atmospheric pressure and allows bubbles to expand further, but it can be justified if it saves substantial time in getting people to a suitable chamber. If possible, people should fly in a plane pressurized to sea level, or the plane should fly at as low an altitude as is consistent with safety. Breathing oxygen is also recommended.