Gas Embolism Health Article

Definition

Gas embolism, also called air embolism or arterial gas embolism, is the presence of gas bubbles in the bloodstream that obstruct circulation.

Description

Gas embolism may occur with decompression from increased pressure. It typically occurs in ascending divers who have been breathing compressed air. If a diver does not fully exhale upon ascent, the air in the lungs expands as the pressure decreases, overinflating the lungs and forcing bubbles of gas (emboli) into the bloodstream. When gas emboli reach the arteries to the brain, the blood blockage causes unconsciousness. Gas embolism is second only to drowning as a cause of death among divers.

In rare cases, gas embolism may also result from trauma or medical procedures, such as catheterization and open heart surgery, that allow air into the circulatory system.

Sometimes, the term "the bends" is used to describe any manifestation of decompression sickness, including gas embolism. Specifically, the bends refers to a condition caused by dissolved nitrogen leaving the tissues too quickly on ascent during a dive. It is manifested by pain, often in the limbs and joints.

Causes and symptoms

Gas embolism occurs independently of diving depth. It may occur in as little as 6 ft (2 m) of water if the swimmer has access to a source of air and takes even one breath underwater. Gas embolism is frequently caused when divers hold their breath during ascent. It may also result from an airway obstruction or other condition that prevents a diver from fully exhaling.

The primary sign of gas embolism is immediate loss of consciousness, which may or may not be accompanied by convulsions.

Diagnosis

Any unconscious diver should be assumed to be the victim of gas embolism, regardless of whether consciousness was lost during or promptly after ascent. A doctor may also find pockets of air in the victim's chest around the lungs and, occasionally, a collapsed lung from overinflation and rupture. Coughing up blood or a bloody froth around the mouth are visible signs of lung injury.