Top Tricks for Little Pricks

One of the things we hope to share on here are those practical tips people use in day to day practice. There was an obvious spot to start.

This is a post about frustration. It’s a post about humility. It’s a post about annoyance and triumph that shouldn’t be treated as a victory.

It’s about cannulation.

Getting a cannula in the patient can be the most mundane, most satisfying or most frustrating part of a day at work for a kids’ anaesthetist. Cannulation is not just useful clinically. It has an excellent habit of keeping any practitioner from getting too far ahead of themselves, just when they are feeling like the supreme clinician.

Anyone who has worked with anyone else has also seen or heard lots of different tips and tricks that individuals have built into their practice over the years. Of course, if there was a single thing that worked in every single patient, we’d all do it that way.

We thought we’d collect tips from a range of clever people to start building up a list of things that people make a point of doing when cannulation is a little difficult. Sometimes they’re really simple things. Sometimes they’re very particular. Most of them are probably in the setting of the child who has undergone inhalational induction (those kids can still be hard of course). Hopefully people will feel moved to add their own flashes of brilliance in the comments.

Here it is – a compendium of cannulation classics from Drs Justin Skowno, Su May Koh, Hillel Hope, Ramanie Jayaweera and Ian Miles. Oh, and me (Andrew Weatherall).


  1. Look everywhere

“Sometimes when I’ve missed out, I go to look at another limb and realise there was a way better choice there. Maybe I went to the first spot because it was closer, or because it would be in a slightly better location once the patient was positioned. Those factors aren’t nearly as convenient as a cannula that’s in. So I try and remember to have a quick look everywhere.” (AW).

“If it looks like it might be difficult, spend as long you need to in identifying the best vein before actually starting your first attempt.” (IM).


  1. Position and preparation

“Get comfortable – the worse your position, the lower your success rate. Sitting is ideal and preserves your back too. And set everything up, including the bandage and fresh cannulae for if you miss. This allows you to quickly move between attempts and reduces the stress of the whole affair. Do not tell everyone how terrible you are at cannulation when you fail on the first attempt. Veins can sense this and will automatically vanish.” (JS)

“Why is it that anaesthetists seem to pride themselves on not optimising the environment to get a procedure done? Better position improves your success rate. There’s a reason surgeons put the table in the position they need. It makes motor tasks easier to perform.” (AW)


  1. Short, sharp moves

“I’ve seen some people prefer to slowly advance the needle. I find that all too often the vein just seems to see it coming and shift slowly away. My success rate went up when I switched to a series of short, quick moves with a pause between. It works.” (AW)

“When actually cannulating, practice getting through the skin quickly, but not going too far, whilst keeping the skin slightly tensioned with your supporting hand. This will reduce the chances of squashing the vein, not seeing the flashback and then wondering where all the blood is hosing from when you withdraw the supposed failure of a cannula.” (JS)


  1. The old saline trick

“Sometimes, particularly in the small veins (or small kids and small cannulas), it takes too long for that flashback to declare itself. I use this trick all the time – flick the back of the cannula off (I think this only works with a non-safety cannula). Then flush the whole needle hub with some saline. You get left with saline in the hub behind the needle. When you’re cannulating, the second you hit the vein, you see a sudden change in the saline then a thin ribbon of blood comes through. (This will sound nerdy but it’s one of those moments of quiet art in the middle of an anaesthetic). I feel like this trick has stopped me prematurely pushing on and ending out the back of many a small vessel.” (AW)



“I fill all my cannulas with saline. I have to warn others working with me every time or they can get a bit of a shock because the flashback looks different but it’s much quicker and stops you going straight through the vein.” (SMK)

After (missed the pretty ribbon bit).

After (missed the pretty ribbon bit).


  1. Make a hole

“When using a 24G cannula, consider making a separate skin incision with a 19G needle (bevel oriented to one side). The lack of skin “drag” with subsequent cannulation gives you a better chance of feeling the “pop” of cannula entering vein. (The slow flashback through these small cannulas makes the identification of timing of venous entry difficult, if the pop is masked by skin drag.)” (IM with an endorsement from AW too)


  1. Common Things are Common

“Focus on areas where veins are reliably located – dorsum of the hand in line with the 4th metacarpal, cephalic vein at the wrist and long saphenous vein anterior to the medial malleolus.” (HH)

“Remember the consistent sites in kids – back of the hand over 4th metacarpal (even if you can’t see or feel it in chubby 1 year olds), the tiny but consistent and very superficial vein on the palmar aspect of the wrist (24G only), the saphenous vein, and the antecubital fossa veins in their various locations.” (JS)

“There are some spots people often forget to look which are just as commonly there. The back of the wrist just above the palm (around where they do the incisions for a carpal tunnel operation) often has a vein that everyone forgets.” (SMK)


  1. Use Better Eyes

“Use ultrasound: We definitely underutilise this tool. Kids with no peripheral veins to be seen or felt will usually have some veins at the antecubital fossa or just above this area.” (HH)

“Use an ultrasound early, if you have it. Even for peripheral cannulation, knowing there is actually a vein deep in the folds of fat is a reassuring thing.” (JS)

“If cannulation looks difficult, get the ultrasound early. It increases your options – forearms, cubital fossa and above; and of course the long saphenous vein.” (SMK).


  1. Drop the Anchors

“When cannulating veins on the back of the hand, hold the patient’s hand with a small amount of pressure from 2nd to 5th metacarpal, creating a small upwards arc/curve across the back of the hand. The slight lateral skin tension helps to anchor those mobile veins.” (IM)


  1. A Good Clean Helps

“A quick clean with an alcohol swab isn’t just about cleaning the skin. The moisture left behind interacts with light a little differently and sometimes you can pick up contours on the skin which reveal a lurking vein. This is a particular tip for the back of the hand and is one I found very handy over years cannulating sickle cell patients for exchange transfusions and the like (so it happens to work particularly well for those with darker skin).” (RJ)


Should we stop at nine? We can’t pretend this is an exhaustive list (though you can see a few come up again and again). Cannulation is a good example of a technical skill where there is more than one way to get it done. We could probably have listed “don’t be shy about getting someone else” too because sometimes it just needs a set of fresh eyes.

Anyway, maybe there’s more than nine. We sure hope so because that could be what the comments are for. Over to you. Bring us your huddled masses of cannulation tips and tricks. We could all do with being better.


Note: The image of cannulation in the post came with consent from the family involved. 


26 responses to “Top Tricks for Little Pricks

  1. Tap the skin repeatedly over the vein and it will dilate.

    Don’t shine a bright OR light on the skin. Better tilt the hand 90 degrees to the ambient light. You will see shadows that will show where the vein raises the skin.

    Use a esmarch tourniquet starring at the axillary and wrap dis tally toward the hand. This will dilate the vein with all the blood of the upper arm.


  2. Thanks Minh. That’s very excellent feedback although of course:
    1) I’m sure none of the clinicians are horrible;
    2) We’re just providing thoughts – it’s the clinicians who will take anything useful away and do the hard work of getting more excellent.

    PS I know you already get that 🙂


  3. Point 3 is something I agree with especially. One point I’d add is the value of the pause between advances. With the small 22 & 24 g safety cannulae it takes a moment for the blood to track up the cannula and indicate correct placement. The pause is gold!


  4. Beautiful. We can intubate, we can place pulmonary artery catheters, dialyse via a vascular catheter but the art of placing a cannula is where it all begins.

    Thank you for so eloquently describing this most essential skill.


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  7. Ps if you get a time and you happen to be looking for more post ideas a similar thread on top tips for successful LPs would be very much appreciated. Thanks again!


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  12. i am very frustrated..every time i vannulate a baby i see the flush back then miss the vein ….i do not know why ….how can i solve this problem…hope you advise me


    • Hi Helana,
      A huge apology for the delay in response. You’ve probably solved this in the meantime by being clever. The site got very non-watched through COVID (and general life). Always hard to know too definitely when you’re not there to watch. However the three commonest things would be:
      – The cannula is on a slight lateral angle to the direction of the vein. As in, you think you’re lined up really well to hit it, but then if you imagine you draw a line tracing the line of the cannula length and extending out across the skin you would see it’s heading to either the right or left of where the vein ends up. So as you advance further you head out the side.
      – Going through the back wall. This is when that angle that you strike the vein is quite acute (this seems to arise because people get told to break the skin at 30-45 degrees which is overkill – even if you get through the skin at this level flattening out is good) so when you advance a little the sharp leading part of the bevel hits that back wall. Sometimes you can rescue that one. But the way to avoid it is a combination of things in the post – after getting through the skin flatten right out, try the saline in the hub trick, consider the 180 twist.
      – More rarely you are so excited by hitting the vein and getting that flash back that you try feeding off the cannula immediately. In case it just hits the top wall of the vein without entering the vein.

      Trying to figure out which one is in play (and it might be multiple of them or different things each time) requires really paying attention to what you’re doing as you’re doing it. Super difficult if you have a kid who is a bit mobile and a lot not excited. But get a sense that your right/left alignment is good, and then pay attention to your angle of approach to the vein and that might be a start.

      Go well. You’ve definitely got this.


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