Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Radial artery puncture is a medical procedure that is performed in order to obtain arterial blood sampling for gas analysis. A needle is inserted into the radial artery and spontaneously fills with blood. The syringe that is used is prepacked and contains a small amount of heparin, to prevent coagulation or needs to be heparinised, by drawing up a small amount of heparin and squirting it out again.