Gas can enter arteries (arterial
gas embolism) due to alveolar-capillary disruption (caused by pulmonary overpressurization, e.g., breath-hold ascent by divers) or veins (venous
gas embolism, VGE) as a result of tissue bubble formation due to
decompression (diving, altitude exposure) or during certain
surgical procedures where capillary hydrostatic pressure at the incision site is sub-atmospheric. Both AGE and VGE can be caused by iatrogenic gas injection. AGE usually produces strokelike manifestations, such as impaired consciousness,
confusion,
seizures and focal neurological deficits. Small amounts of VGE are often tolerated due to filtration by pulmonary capillaries. However, VGE can cause
pulmonary edema, cardiac "vapor lock" and AGE due to transpulmonary passage or right-to-left shunt through a
patent foramen ovale. Intravascular gas can cause arterial obstruction or endothelial damage and secondary vasospasm and capillary leak. Vascular gas is frequently not visible with radiographic imaging, which should not be used to exclude the diagnosis of AGE. Isolated VGE usually requires no treatment; AGE treatment is similar to
decompression sickness (DCS), with
first aid oxygen then hyperbaric
oxygen. Although cerebral AGE (CAGE) often causes
intracranial hypertension, animal studies have failed to demonstrate a benefit of induced
hypocapnia. An evidence-based review of adjunctive
therapies is presented.