What happens if air enters into vein during an injection?

Answer 1

It all depends on the amount of air. Medical personnel take pains to avoid introducing any air into an IV line at any time. Most of the time, a tiny amount of air presents no problem - but that's most of the time.

The two major factors at play are emboli and clotting. Emboli (plural of embolus) are "plugs" or blockages that are actually air bubbles, which jam a blood vessel and prevent blood from passing through it unimpeded. Lack of blood through a vessel means lack of oxygen, and the tissue itself can die. If the tissue is skin tissue over a small area (as would happen with emboli blocking capillaries at the skin), you'll eventually slough off the involved dead tissue and no harm done. On the other side of the equation, blocking blood flow in the brain can be lethal or highly damaging.

The other problem is clotting. When your blood is exposed to air, it starts to clot. On the surface of your skin, this is a good thing - it stops bleeding and forms a sort of bandage. However, inside your circulatory system this too can be problematic, and even lethal.

While there's no way of telling for certain what the effects of a given injection will be, the more air injected, the greater the danger. Tiny bubbles in an IV line or hypodermic are to be avoided, but rarely will have an effect on the patient. Large injections (the prior writer mentioned 50 cc) are potentially lethal.