In a few words

Inserting an intravenous (IV) cannula

Inserting an intravenous (IV) cannula – September 2015

I once, perhaps unfairly, said to an IC student that if he was unable to insert the IV cannula he held in his hand into the patient’s vein, we could do little more than be simple first aiders. Inserting an IV is a standard skill now expected of paramedics. But inserting one does nothing. It is what you do with it that counts meaning of course the drugs or fluids chosen. It still represents a route frequently required for providing critical out of hospital therapies.

To have these options available, inserting an IV must first be mastered. Such mastery is to me similar to playing golf. Watching a golfer looks relatively uncomplicated. You walk up to the ball, stand with legs apart, hold the handle of the club, place the head of the club beside the ball, back swing over your shoulder, swing the club head in downward arc again and strike the ball. Easy.

Only it isn’t easy when you try. There are so many little things to get just right. If you don’t get them right you don’t just play poorly, you don’t play at all. If you don’t bend your knees you stand up straight and swing over the ball. If you don’t hold the club properly you hit the ball to the left or right lost forever in long grass or endangering someone on the next fairway. If the arc is wrong you might bring up a lot of dirt and grass and move the ball a few inches. And the clubs are all different. You have to choose the right one for the job in the first place. Some are designed to hit out of the sand, others to hit the ball a very long way and one even to putt.

Inserting an IV is little different. There are lots of details and if you get just one wrong, failure awaits. So here are some of those details to take care of.

  1. Know your devices in advance. Different brands have different sharpness, feel in the hand, method of insertion, flashback viewing. Familiarity makes life much easier.
  2. Consider which IV you need. Larger bore and longer needles need bigger veins so may be harder to insert into really sick people. They can also hurt more. Only choose a bigger one if that is what you think you might need for treating. A small volume of pain relief for an arm fracture hardly needs the biggest IV in the box.
  3. If in doubt about chance of success, err on a smaller size. A patent 20G needle is better than several unsuccessful larger attempts.
  4. Don’t rush, even if it is a cardiac arrest. Apply a tourniquet early, before preparing support equipment and drawing up drugs. This gives veins a longer chance to fill. Moreover, apply more than one tourniquet. Apply one on each arm and consider even placing one on the calf of a lower leg in cases such as paediatric or suspected difficulty. You may as well have a good look at as many options as possible and not be fooled into persisting with a poor option on one limb only. Where possible, allow the limbs to hand dependant and with an occasional fist clench to help the filling.
  5. Place the tourniquet on the upper arm/bicep first. This allows all options including cubital fossae to be considered. It may look cool to be different and place it down on the forearm but there are no fall back options. Such a lower tourniquet can be added second if you decide that you want to focus on a vein in the hand.
  6. When you pull the tourniquet tight, make sure your own finger is tucked under the clasp between it and the patient to avoid painfully pinching the patient’s skin. Also make sure that you can still feel the distal pulse. It is a venous tourniquet and not arterial. Veins won’t fill otherwise.
  7. Following from point four, prepare your equipment whilst the veins fill. Lay out a clean pillow case or pad to provide a working surface. It won’t be sterile, but it will be cleaner than the floor or the patient’s bed. It will also look professional. This is a good way to keep all of your IV equipment and drugs safely in one place so things don’t get lost. It is also very useful when people are moving around the scene, such as cardiac arrests, as it helps to mark out your clean work area. Very few people place their big boots down on such a surface but they will if your space is just more of the mess.
  8. Be tidy and safe. The first item that comes out after the tourniquet is the sharps container. This certainly comes out before the IV itself. If there isn’t one, then the IV does not come out. The days of sticking the dirty needle into a mattress or carpet to be tidied later are long past. If that is you, you are a danger to anyone near you. It isn’t uncommon for some ambulance services to have higher needlestick injury rates amongst cleaning and mechanical staff than the paramedics themselves. The next item that comes out is a small infectious waste rubbish bag. Don’t leave bloodied waste at the scene for the grieving family to have to tidy up later.
  9. When choosing the actual IV site, consider not only finding a suitable sized vein, but also what will work for the patient. Novices tend to focus on the easy to get cubital fossae since it is larger and often obvious. This site means the patient will have to sit uncomfortably with their arm held straight. Some patients may not cooperate, such as when agitated. By all means use this if you have to. It is great in cardiac arrest or if administering adenosine, but it might be preferable to choose the forearm or back of the hand. It will likely be easier to secure in those places as well.
  10. Swab the site several times over a large area. Use a few swabs, don’t be stingy. Paramedics are often relatively unclean compared to other medical professionals. We don’t see the phlebitis and sepsis that result days later. Don’t be fooled by urgency. Be clean always. And once you have swabbed, don’t keep retouching the site. If you do, swab it again. Your gloved finger will not be clean.
  11. Not all veins will be visible. Some will only be felt using the fingertips. Practice feeling veins as well as seeing them. Sometimes you can feel the hard little valves in them as small lumps. As you follow the vein you can feel other valves. You can even mark with a pen where two of them are giving you a line in between them where the vein, and hence your target site, will run.
  12. Occasionally you will attempt to insert an IV without being able to either see or feel a vein. This ‘blind’ attempt should really only be if you absolutely need the IV and have looked everywhere. To help, look at your own arms first to get an idea where veins are commonly found. Placing your finger in the middle of the cubital fossae then rolling it onto either side left or right will frequently place the finger over a vein. They do run on slightly different angles though. There is also a vein that runs along the inside of the wrist along the line of the thumb. Don’t forget the little veins on the underside of the forearm either though they are small and painful.
  13. Have a last minute check that the plastic cannula will easily feed off the needle. Slide it forward just slightly to ensure it is free to move without resistance.
  14. Pin the vein down now so that it cannot move during insertion. This is a key point where surprise failure awaits. You can do this by pulling distally on the skin from the insertion site toward you. This is often called putting traction on the vein. If you are too close your fingers might get in the way of insertion. Alternatively you can cup the limb from beneath with your hand, clasp the skin on either side with your fingers and pull downward. This too pulls the skin around the vein tight. Experiment with both as sometimes one will flatten the vein making it difficult to cannulate.
  15. Whichever option you choose, keep the pressure held on until the needle is successfully in the vein. Letting go of the traction too early, even to help feed the cannula into the vein, is a common mistake and can lead to failure. The IV has a bevelled end on it. This allows the needle tip to enter the vein before the plastic cannula does. Once you observe a flashback of blood into the cannula, reduce any angle to almost flat then feed the needle forward a few millimetres. You must get the plastic cannula into the vein as well. The bigger the needle, the more you have to progress the needle for this to happen. If you let go of the traction, the vein will move, frequently away from your precious needle tip. This often explains many successful flashbacks that cannot then be fed into the vein or function later.
  16. Now you are ready to insert the IV. Sit yourself so that you can hold the needle directly in line with the direction the vein runs. If you come at the vein from an awkward side angle, you will likely just push through the wall on the other side.
  17. The angle you have the needle compared to the vein will vary with how superficial the vein is and how big the needle is. Prominent veins are right there near the surface and only need a slight angle. The ones that you can only feel are a bit deeper and need a bit more angle to reach. Also bigger needles have a bigger tip that can push through the bottom wall if you go in too steeply.
  18. Have you informed the patient what you are going to do? Surprise attacks are easily confused by lawyers as lack of informed consent so don’t go there. It makes some patients angry too.
  19. Make sure you have the longest part of the bevel facing downward. It can be hard to tell with the really little IVs, particularly if you are using fifty year old eyes!
  20. Take note of where the needle end is and where the vein is. If you are on top of the vein, push straight in. You might be alongside. That is okay but beware of the vein being able to move sideways away from you. This can trick you into increasing the angle to push into the vein risking going straight out the other side. You can also be tricked into trying to push the needle in a straight line along the vein so never actually penetrating into it.
  21. If you have missed the vein and there is no flashback, you may be tempted to keep digging around until you find it. This can hurt the patient. It might also be because you have the needle and the vein too far apart. Look at your position without moving the needle and consider if you can correct the situation using traction on the vein or whether it is better to simply have another attempt instead.
  22. Once the cannula is in place and fed up, ensure it is patent with a good flush of fluid from a syringe or a free flowing IV bag. Secure it in place well now and not ‘when you get a chance’. You don’t want to see the IV pulled out now because of sloppiness now.
  23. Make sure you release the tourniquet as soon as the needle is pushed up into place in the vein. The back pressure can push out the needle in hypertension, cause messy blood loss as you pull out the needle from the cannula or lead to a large hematoma forming if you are not properly in place. This rule may vary if you are withdrawing blood for testing first.
  24. Very hypotensive patients, those with profound blood loss and small IV cannulas often have sluggish or even no flashback. If the IV feels in place and this feedback is missing, consider testing with a flush before you abandon it.
  25. Diabetic patients and those on long term steroids such as COPD patients frequently have extremely fragile veins. Any roughness at all, and sometimes even good technique, can see reasonable attempts fail. Don’t get too disheartened.
  26. Occasionally you will only be able to place a small IV when the patient’s condition warrants a larger needle. Consider this. With a small patent cannula in place, reapply the tourniquet. Using a large syringe you can gently push IV fluid into the vein. This should not be able to escape the tourniquet and will pretty soon start to fill the veins in an arm. It may produce a larger IV option nearby on the arm. More than one IV on one limb is okay. This is a good option if the other arm is traumatised or if you want to use the other arm for blood pressure monitoring without interruption. Note though if you are unsuccessful with a distal IV you can always place another one above it. If you mess up the proximal one, such as a cubital fossae, you shouldn’t then move distally. Any administered drugs and fluid can escape through the damaged site above it.
  27. Is the IV actually totally necessary? Sometimes another route may suffice such as intramuscular (e.g. adrenaline for anaphylaxis) or intranasal (e.g. pain relief). If it is and you are struggling, do you have an alternative option of intraosseous? If you do, it is likely more prudent to turn to this rather than unsuccessfully persevere for a vein that may not come.

Jeff Kenneally –

5 thoughts on “Inserting an intravenous (IV) cannula

  1. Jordan / Reply December 3, 2015 at 7:21 am

    Quite Informative post. IV Cannula is one of the high quality surgical medical instrument that doctor can use for Repeated blood sampling, Intravenous fluid administration, Intravenous medications administration, Intravenous nutritional support, etc.

  2. Jeanna / Reply August 18, 2018 at 8:37 am

    As a student I spent a lot of time to find something like this, thanks

  3. Janna / Reply August 20, 2018 at 3:24 pm

    Thank you for the excellent post

  4. Guy Medic / Reply April 5, 2019 at 11:28 pm

    Thanks, it’s quite informative

  5. Andrew hann / Reply April 6, 2019 at 2:42 am

    This is actually useful, thanks.

Leave a Reply

Your email address will not be published. Required fields are marked *