cannulaA intravenous cannula (pl. cannulae) is a flexible tube which when inserted into the body is used either to withdraw fluid or insert medication. Cannulae normally come with a trocar (a sharp pointed needle) attached which allows puncture of the body to get into the intended space.
To start an IV, first prepare all of your equipment. This will include an IV bag, with connecting tubing, with all the air flushed out of the tubing.
Place a tourniquet around the arm. This should be tight enough to block venous blood flow back to the heart, but not so tight that it obstructs arterial flow.
Wait long enough for the veins in the hands and arm to fill and become tight. In a normal person, this may take 2-5 minutes. In a dehydrated person or someone in shock, it may take longer.
Cleanse the skin of the injection site with alcohol (preferably). If alcohol is not available, use any antiseptic or skin cleaner. Using any cleaning agent (even water) is better than using nothing at all.
Use your left thumb to hold the vein in place while you insert the IV needle at a shallow angle (about a 20 degree angle) through the skin and into the vein.
As you enter the vein, you will feel a slight "pop." You will know you are in the vein when you see blood returning in the "flash back" chamber.
Keep the needle in place with one hand while you push the catheter (which surrounds the needle) further into the vein. This will thread it upstream, securing it into the vein.
Once the catheter is completely inserted, hold it in place with one hand while you release the tourniquet and pull the needle straight out with the other hand. Pressing down over the skin where the catheter tip is located will prevent blood from flowing back out the IV catheter before you have a chance to connect the IV tubing.
Connect the IV tubing and run in the IV fluids briskly, at first. Then slow it down to a steady drip, drip, drip. If the fluid does not flow freely at the beginning, check the IV tubing to see if there are any valves or other obstruction to flow. If the tubing is wide open, but the IV is dripping only very slowly, you are probably not in the vein. Try again.
Put a small amount of Bacitracin or other antibiotic ointment on the IV site, put a bandaid over it, and then tape the tubing in place.