''An air embolism occurs when one or more air bubbles enter a vein or artery and block it.If a doctor suspects that you have an air embolism, they may perform an ultrasound or CT scan to confirm.Symptoms of a severe air embolism might include low blood pressure or difficulty breathing.

An air embolism, also called a gas embolism­, occurs when one or more air bubbles enter a vein or artery and block it. When an air bubble enters a vein, it’s called a venous air embolism. When an air bubble enters an artery, it’s called an arterial air embolism.

These air bubbles can travel to your brain, heart, or lungs and cause a heart attack, stroke, or respiratory failure. Air embolisms are rather rare.

A syringe or IV can accidentally inject air into your veins. Air can also enter your veins or arteries through a catheter that is inserted into them.

Sometimes an air embolism or embolisms are small, and don’t block the veins or arteries. Small embolisms generally dissipate into the bloodstream and don’t cause serious problems. Large air embolisms can cause strokes or heart attacks and could be fatal. Prompt medical treatment for an embolism is essential, so immediately call 911 if you have concerns about possible air embolism.'' - Air Embolism. http://www.healthline.com/health/air-embolism

''The lethal volume of air in an adult human is unknown but is estimated to range from 200 to 300 ml.'' - Volume of Air in a Lethal Venous Air Embolism. http://anesthesiology.pubs.asahq.org/article.aspx?articleid=2026502