Arterial gas embolism

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Arterial gas embolism is a potentially catastrophic event that occurs when gas bubbles enter or form in the arterial vasculature and occlude blood flow, causing organ ischemia. Arterial gas embolism can cause central nervous system (CNS) ischemia with rapid loss of consciousness, other CNS manifestations, or both; it also may affect other organs. Diagnosis is clinical and may be corroborated by imaging tests. Treatment is 100% oxygen and immediate recompression.
(See also Overview of Diving Injuries.)
Gas emboli may enter the arterial circulation in any of the following ways:

From ruptured alveoli after lung barotrauma
From within the arterial circulation itself in severe decompression sickness
Via migration from the venous circulation (venous gas embolism) either via a right-to-left shunt (patent foramen ovale, atrial septal defect) or by overwhelming the filtering capacity of the lungs

Even an otherwise asymptomatic venous gas embolism can cause serious manifestations (eg, stroke) in the presence of a right-to-left shunt. Venous gas embolism that does not enter the arterial circulation is less serious.
Although cerebral embolism is considered the most serious manifestation, arterial gas embolism can cause significant ischemia in other organs (eg, spinal cord, heart, skin, kidneys, spleen, gastrointestinal tract).