Everything about Air Embolism totally explained
An
air embolism, or more generally
gas embolism, is a medical condition caused by
gas bubbles in the bloodstream (
embolism in a medical context refers to any large moving mass or defect in the blood stream). Small amounts of air often get into the blood circulation accidentally during surgery and other medical procedures, but most of these in veins are stopped at the lungs, and a venous air embolism that shows
symptoms are very rare. Death may occur if a large bubble of gas becomes lodged in the heart, stopping blood from flowing from the right
ventricle to the
lungs (this is similar to
vapor lock in engine fuel systems). However, the amount of gas necessary for this to happen is quite variable, and also depends on a number of other factors, such as body position.
Gas embolism into an artery, termed
arterial gas embolism, or AGE, is a more serious matter than in a vein, since a gas bubble in an artery may directly cause stoppage of blood flow to an area fed by the artery. The symptoms of AGE depend on the area of blood flow, and may be those of
stroke or
heart attack if the brain or heart, respectively, are affected.
Pathogenesis
Air embolism can occur whenever a blood vessel is open and a pressure gradient exists favoring entry of gas. Because the pressure in most arteries and veins is greater than atmospheric pressure, an air embolus doesn't always happen when a blood vessel is injured. In the veins above the heart, such as in the head and neck, the pressure is less than atmospheric and an injury may let air in. This is one reason why
surgeons must be particularly careful when operating on the
brain, and why the head of the bed is tilted down when inserting or removing a
central venous catheter from the
jugular or
subclavian veins.
When air enters the veins, it travels to the right side of the heart, and then to the lungs. This can cause the vessels of the lung to constrict, raising the pressure in the right side of the heart. If the pressure rises high enough in a patient who is one of the 20% to 30% of the population with a
patent foramen ovale, the gas bubble can then travel to the left side of the heart, and on to the brain or
coronary arteries. Such bubbles are responsible for the most serious of gas embolic symptoms.
Trauma to the lung can also cause an air embolism. This may happen after a patient is placed on a
ventilator and air is forced into an injured vein or artery, causing sudden death. Breath-holding while ascending from
scuba diving may also force lung air into pulmonary arteries or veins in a similar manner, due to the pressure difference.
Air can be injected directly into the veins either accidentally or as a deliberate act. Examples include misuse of a
syringe, and
industrial injury resulting from use of
compressed air. However, the amount of air that would be administered by a single small syringe is, in most cases, not enough suddenly stop the heart, nor cause instant death. Single air bubbles in a vein don't stop the heart, due to being too small. However, such bubbles may occasionally reach the arterial system through a
patent foramen ovale, as noted above, and cause random
ischemic damage, depending on their route of arterial travel.
Gas embolism in diving
Gas embolism is one of the
diving disorders SCUBA divers sometimes suffer when they receive
pressure damage to their lungs following a rapid ascent where the breath is inappropriately held against a closed
glottis, allowing pressure to build up inside the lungs, relative to the blood. It is termed "gas" because the diver may be using a diving
breathing gas other than
air. The gas bubbles can impede the flow of oxygen-rich blood to the brain and vital organs. They can also cause
clots to form in
blood vessels.
Gas embolism and
decompression sickness (DCS) may be difficult to distinguish, as they may have similar symptoms, especially in the
central nervous system. The treatment for both,up to point of hospitalisaztion,is the same, because they're both the result of gas bubbles in the body. In a diving context, the two are often called
decompression illness (DCI).
Treatment
Recompression is the most effective treatment of an air embolism. Normally this is carried out in a
recompression chamber. This is because as pressure increases, the solubility of a gas increases.
Oxygen first aid treatment is useful for suspected gas embolism casualties or divers who have made fast ascents or missed decompression stops. Most fully closed-circuit
rebreathers can deliver sustained high concentrations of oxygen-rich
breathing gas and could be used as an alternative to pure
open-circuit oxygen
resuscitators.
Pop culture
In season 4, episode 15 of
House, a bus driver had an air embolism from dental surgery.
During the hospital scene in the 2006 re-make of The Omen, Katherine Thorn (played by actress Julia Stiles) has a lethal amount of oxygen injected into her IV (by her son's babysitter) giving her an air embolism followed by almost instantaneous cardiac arrest, killing her.
Further Information
Get more info on 'Air Embolism'.
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