Once you decide where to insert your IV cannula, apply a tourniquet about three finger-widths above the chosen venipuncture site (Figure 22.3a). Then feel for the vein with your gloved finger (Figure 22.3b). Clean the site with alcohol (Figure 22.3c) or soap and water.
Then stretch the skin taut and stabilise the vein with your non-dominant hand — meaning keeping it stretched so that it does not move easily and you miss your target with the needle. Pierce the skin with the IV cannula over vein at a 45 degree angle; first you push the needle into the skin and then aim at the vein (Figure 22.4). As you approach the vein, lower the angle to about 10 degrees and insert the cannula into the vein.
Look for blood 'flash back' (blood shooting back along the barrel of the cannula), which tells you that the needle is in the vein. Release the tourniquet at this point, then push the cannula further into the vein until you are well into the vein.
The cannula is a metal needle with plastic over it, and it is the plastic part that remains in the vein. Gently remove the metal needle part of the cannula, leaving the plastic part in the vein.
You then stabilise the plastic part of the cannula with a plaster, or clean rope or cloth wrapped around the venipuncture site (Figure 22.5).
Connect the IV tubing to the IV fluid bag and open the roller clamp to let fluid flow down the tube. Do this before connecting the other end of the tubing to the cannula. Flushing with fluid ensures there are no air bubbles in the tube before you begin infusing fluid into the patient.