IV Cannulation

Venous Cannulation

Indications 

Fluid, drugs, emergency situations, feeding.

Need

• Cannula
• Chloroprep/alcohol swab
• Tourniquet
• Cotton wool and tape (in case you miss the vein)
• Sharps bin
• Saline and syringe to flush

Method

1. Prepare the equipment. Remove the cap of the cannula and leave in your tray,
2. Introduce & explain. Say that no needle is left in arm only a bit of plastic, and that the patient needs to be careful.
3. Set up drip stand with a bag of fluid (checked by nurse)
4. Put some tissues underneath the arm
5. Palpate a vein. The most convenient site fot the patient is usually the back of the hand.
6. Apply the tourniquet about 20cm above the site of insertion.
7. Wipe with steret
8. Slowly insert the cannula through the skin at an angle of about 30 degrees until you get a flashback of blood. When you see this flashback, gently flatten the cannula so it is at 0 degrees to the skin and advance another minimally 0.5 cm. Loosen the tourniquet. Now start to slide the plastic cannula whilst withdrawing the trocar (so effectively the metal trocar does not move relative to the skin) until it is fully in the vein.
9. Remove the trocar, blood should start to exit the cannula. Apply the plastic cap to the cannula.
10. Flush cannula with 5-10ml of 0.9% saline 
11. Secure the cannula with a VacuFix/Tagaderm.
12. Connect fluid tube. 
13. Bandage a loop of the tube to the arm. 
14. Write up the cannula care chart if available

Top Tips:

• Relax and believe you can do it. Never rush a cannula as you will miss it.
• The easiest vein is probably in the antecubital fossa. However this is uncomfortable for the patient as they have to keep their arm straight. Another good vein is just below the thumb on the radial wrist, known as the "houseman's friend," this is probably the first place you should look. Other veins (in order of easiness) are on the back of the hand, further up the dorsum of the wrist on the radial side, the feet, the legs, the ventral surface of the arm, above the elbow.
• You can ask the patient where people have inserted cannulas in the past - they may well know the easiest places. 90% of patients will say they are hard to cannulate, this is probably because there are a lot of bad cannulators out there.
• Good veins are large, easily palpable, immobile, with thick walls. If you can see but not feel the vein it is not a good vein. If it is very mobile (like the ones further up the arm) it will move as you attempt to put the needle in. To avoid this pull the skin taut, and go in initially at an angle of 30 degrees. Veins which come off at the junction of two veins are also usually quite immobile. If the vein looks big but thin the risk is of puncturing the other side causing an unsightly haematoma and preventing insertion. If you think this is likely to happen puncture and advance the cannnula very slowly.
• If you keep easily getting in to the vein (with a flashback) but find you cannot advance the cannula you are probably not in far enough. Once you get a flashback you must flatten the cannula against the skin and insert the trocar a little more to ensure that it is not just the bevel that is within, but the end of the plastic cannula tube.
• Smaller cannulas are easier to insert. Blue is the easiest to get in followed by pink, green, orange, and white.
• Tapping the vein lightly, wiping with chloroprep/alcohol, and getting the patient to clench their wrist all make the vein more prominent
• No veins: hang the patients arm below the heart, or apply a heated towel
• No veins: some people use double tourniquets, one about 10cm above the other
• Oedemeatous veins: apply a tourniquet on the insertion site for a few minutes to create an indentation (temporarily removing the oedema from that area)
• Large "ropy" veins in the elderly are easily ruptured. Try and insert the cannula without using a tourniquet
• Veins with valves are hard to insert cannulas in. You can attach a syringe filled with saline and inject whilst inserting to open up the valves.
• Ask a nurse . The majority will not do them, but some friendly ones will.
• Don't give up if you don't get it first time, try at least 3 or 4 times. Remember that the cannula does need to be inserted and somebody has to get it in - another person will likely have as much trouble as you.
• Go and have a coffee and come back half an hour later. Most cannulas are not urgent (although remember that some are)

Web Resources

• Nursing Link: IV therapy. The best resource I have found on the web for cannulation. Cannula tips are few and far between for some reason. Ironically and unfortunately the majority of UK nurses will not cannulate.