the real problem when you puncture an artery is as follows.
You have a vessel which transports blood, under immense pressure (compared to veins). Once you punch a hole in this vessel, blood will leak out, quicker, faster and under more pressure then a vein. When you don't push on your site after hitting a vein, you will get a bruise. This is due to blood leaking out from your vein, and pooling under your skin. The pressure on arteries is at least a tenfold higher. The only right thing to do when you puncture an artery is to keep strong pressure on the site for at least 15 minutes, and if possible constrict the blood flow to said area (Don't constrict blood flow for more than a minute at a time though).
So hitting an artery is bad news, due to you being unable to stop the internal leakage of blood that happens under your skin. this can lead to a HUGE number of complications. Also, anything that enters an artery will still have to go through your bodies capillary bed, and here, pill binders and other insoluble things will do even more damage. If you frequently inject into your arteries, you have accumulation at the capillary beds, as opposed to your lungs (Anything you shoot into a vein will go through your pulmonary circuit first, before entering the systemic circuit).
If i knew i hit a vein, i would imeadiatley withdraw my needle and keep pressure on the site for at least 15 minutes. I would keep my affected limb elevated also.
Hitting an artery with a sterile needle and clean solution, is one thing. Hitting one with a dirty, blunt, used needle and some cooked up street drugs, is another game altogether. I suggest you see medical professionals ASAP, and tell them exactly what you did, when, and how long ago. This is a matter of limb or no limb, life or death.
