Clinical ArticlesMedical Students / JMOs

Common procedures: tips and tricks – IV cannula insertion

IV cannula insertion

The best way to get good at inserting cannulas is to practice, by and large it’s a feel thing, and one that you get better at as your motor-memory in your fingers improves. Like anything though, it helps to have the right technique and most of the mistakes you’ll make can be put down to forgetting to do one of the basics. The approach to getting good at cannula insertion, therefore, is to be very familiar with the basics and accept that you will miss and that so long as you stick to the basics you will get better. So I’ll go through some of the common pitfalls and tips to avoid those pitfalls.

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  • Preparation. This is relevant for all procedures and just as relevant for IV cannula insertion. You need to know what you need and how to arrange it.

    • I almost always cannulate sitting down on a chair, it makes sense to optimise your environment and if you’re sitting down you’re sure to be balanced and in a position that is familiar and comfortable to you
    • The arm should be positioned according to the vein you want to cannulate, for the cubital fossa a relaxed arm that is slightly bent is usually best; ideally resting on a pillow. In the wrist or the dorsum of the hand you should manoeuvre the arm so it is just above your lap. This may seem like a tedious point, but think about how much attention professional tennis players pay to the little bits and pieces, you want to negotiate the environment so it maximises your chance at success
    • A couple of things need to be positioned next to the patient’s arm and within easy reach. These are: (1) the bung – lest blood flow all over the floor after you’ve taken the needle out, (2) the vacutainer if you’re taking bloods at the same time for the same reason, (3) gauze to place directly under the cannula access point to collect the blood that will inevitably drip between taking the needle out and attaching the bung (or if you miss and need to tape some gauze to the skin), and (4) the relevant blood tubes if you’re taking blood.
    • I almost always have a paper towel or ‘bluey’ underneath the arm in expectation of blood dripping down on to the bed sheets or pillow. I find dripping blood very reassuring as it tells me I’m in the vein but having made many a bloody mess over the years and needed to ask many a nurse to change sheets I tend to be pretty particular on this point.
  • Finding a vein. The places to look are the dorsum of the hand, the cephalic vein which lies on the medial surface of the forearm starting between the thumb and the index finger (usually easiest to locate about 10 degrees above the location of the radial artery), the anterior surface of the forearm, and if no luck then the cubital fossa. Usually the cubital fossa is the last place to look because it’s an annoying place to have a drip going.

    • The best vein is the one you can feel, not necessarily the one you can see. a easily palpable vein is always preferable to a easily visible vein
    • Feel on your hand for your flexor and extensor tendons and muscles and note that at their edges they can feel a lot like a vein, you can avoid cannulating a muscle by feeling it as they flex or extend their fingers, and noting that while there is a compressible bit of tissue that feels like a vein it only has one edge whereas a vein has two. This sounds silly but it’s more deceptive than you think.
    • There are veins on the anterior surface of the wrist that are usually very visible but also very small, and these are not a first choice cannulation point but some people are reluctant to cannulate them at all. If they feel good, they are a reasonable choice (but it’s an awkward position for the patient so it should not be your first choice).
    • The best veins are the ones that are straight, and not tortuous and that bifurcate distal to the point of attempted insertion (this tends to anchor the vein and limit rolling), try to feel along the direction of the vein so that you are inserting the cannula in the same direction that the vein is travelling. Sometimes veins travel almost horizontal and you will miss if you insert the cannula in a strictly distal-proximal direction.
    • Veins can ‘come-up’ with some rubbing or tapping, some people slap the vein to try and make it come up but this is unnecessary. The idea is to disturb the mast cell and get them to release histamine. I usually just give the vein a bit of a rub while I apply the alcohol antiseptic and thereby avoid needing to slap the patient’s arm.
  • Choosing a cannula. As a general rule of thumb, use a 20G for a female and a 18G for a male. Where possible however you should try to insert an 18G for practice’s sake but tiny veins necessitate a smaller gauge cannula and if you’re not having luck try going down a size until you get more confidence. For scans with contrast they usually want at least a 20G in the cubital fossa or an 18G.
  • Insertion technique. Typically you’re told to insert the cannula at 45 degrees but there is no good reason to do this. You should insert the cannula at about 20 degrees or less and adjust according to the depth you think the vein is. For veins that seem to be just underneath very frail paper-like skin, your angle should be almost 0, for patient’s with deep veins or lots of adipose tissue then 45 degrees might be appropriate

    • Some doctors who are very good at cannulas insert them fast, this does not mean you should, there is no added benefit from speed; do it slowly so you don’t go through the vein and end up out the other side. Advance slowly, until you see flashback in the container, advance another 1-2mm because the needle tip extends further than the cannula lumen and when the needle is first in the vein the cannula tip is not; at this point you should drop the angle of the cannula to avoid inserting through the vein and then advance the cannula lumen up the vein. If at any point you lose flashback (evidenced by the container not filling up with blood anymore or if the cannula lumen covering the needle is not red) you have lost venous access. You can try to manoeuvre the cannula to get back in but be aware that the vein may have burst. This is evidenced by a circular swelling or haematoma developing around the vein site. At this point you need to remove the needle and apply pressure with gauze as soon as possible.
  • Always wear gloves. There is never a situation where you should not be wearing gloves. Do not ever compromise on this rule.
  • Once you have inserted the cannula, achieved flashback and you are about to withdraw the needle use your non-dominant hand – thumb and index finger – to hold the cannula in place so it can’t fall out. Use your middle and ring finger to occlude the vein distal to the insertion site of the cannula. This will limit the amount of blood that can drip out between removing the needle and attaching the bung or vacutainer.

    More to come as I think of them. Contributions/comments/criticisms/thoughts welcome and gratefully received.

  • This is great!<br />
    Thanks for you sharing your tips :)
    <span style="font-weight:bold;">Additional cannulation tips</span><br />
    <br />
    Here are a few additional cannulation tips that I&#8217;ve come across over the past couple of years. By now you hopefully already know the general procedure of cannulating and just need some additional tips to improve your strike rate.<br />
    <br />
    In no particular order,<br />
    <br />
    <br />
    <ul><br />
    <li>Choose the right site and cannula. Before cannulating should have a pretty good idea of why you are cannulating and what kind of fluids/medications you are going to be giving through your cannula. It might be tempting to stick a little 22G in the antecubital fossa but this is useless for the patient who is going to be admitted for several days requiring IV fluids / meds. The antecubital fossa and hand are uncomfortable places for cannulas and frequently tissue or get yanked out. If you anticipate the cannula will remain in for a few days it is best to get access somewhere on the forearm. By now you should be aware it is best to save the antecubital fossa for bigger cannulas during emergencies (but if it&#8217;s the only place you can find it&#8217;s better than nothing at all!). The hand is an excellent place to cannulate if it is not going to be used for too long or if you need more convenient access (both cases apply to day surgery patients, for example).<br /></ul><br />
    <br />
    <ul><br />
    <li>Double flashback. Once you hit a vein you will get flashback into the chamber of your needle. This doesn&#8217;t mean you&#8217;re in the vein yet! Due to the bevel on the need you will get flash back as soon as the tip of the needle is in. Advance your need slightly further (~1mm) and then angle the needle to almost flush with the patients skin and advance another 2-3mm. Withdraw the needle very slightly and you should see blood travelling up inside the cannula; this is the second flash back! If you do not see the second flash back then your needle may be in the vein but the cannula is not yet there (next time you have a cannula out have a look how far down the needle the cannula actually starts). If this happens, reintroduce the needle, advance another 1-2mm and try again. Once you know you are getting that second flash back, reintroduce your needle (for guidance), and fully advance the cannula.<br /></ul><br />
    <div style="text-align:center;"><img src="http://i.imgur.com/jLcbG.png" alt=" " /><br />
    <br />
    </div><br />
    <br />
    <ul><br />
    <li>Try again. If you attempt to cannulate but completely miss the vein (you might not have anchored well enough and it rolled away) do not remove the needle! Puncturing the skin is usually the most painful part. Withdraw your needle slightly (without taking the tip out of the skin) , re-angle it, and try again.<br /></ul><br />
    <br />
    <ul><br />
    <li>Cleaning with your alco wipe. You just spent the time to put on a tourniquet, get the patient to pump their hand, tap on the vein (which, by the way, is painful when you have a tourniquet on) and plump up that juicy vein, and then you go and ruin it by rubbing all the blood out of the vein with your wipe. Remember that your veins have valves and if you rub the vein up and down you might push all the blood out of that vein making life difficult for yourself. To solve this, simply clean your site with downwards motions only (from proximal to distal). While only a minor point it may mean the difference to hitting that vein or not.<br /></ul><br />
    <br />
    <ul><br />
    <li>Entry site. You don&#8217;t have to enter a vein from directly on top of it. This is particularly important with veins in the hand. By pushing on the tough skin of the hand directly above a vein it is easy to collapse the vein beneath. Eg:<br /></ul><br />
    <div style="text-align:center;"><img src="http://i.imgur.com/t7akO.png" alt=" " /></div><br />
    <br />
    <ul><br />
    <li>Instead, you could enter the skin beside or distal to the vein you wish to cannulate, re-angle your cannula under the skin, and then enter the vein.<br /></ul><br />
    <br />
    <ul><br />
    <li>Forked veins are your friend. A great way to avoid the above problem on the hand is if you are lucky enough to find a patient with a forked vein on their hand. In this circumstance, enter just distal to the forked section (black dot in pic below) and then advance your needle into the fork and straight up the middle. The added benefit is that these forked veins are generally anchored better and you won't have the problem with them rolling away (you can't miss!).<br /></ul><br />
    <div style="text-align:center;"><img src="http://i.imgur.com/IXTGu.png" alt=" " /></div><br />
    <br />
    <br />
    <br />
    More to come when I think of/remember them (and if people actually read them :p).
      What a terrific post! And the pictures! Some tips I can use as well, I agree with almost all of it. I'm a little uncertain about the alco-wipe point, since I usually find rubbing the vein up and down a more effective method than tapping it (which I agree can be quite painful), but intuitively Shizzy's point seems correct so maybe in future I'll just rub down-ways and that might help me.<br />
      <br />
      The other useful thing about not cannulating the cubital fossa (if you're confused the cubital fossa and the antecubital fossa are the same thing and I think Shizzy's just trying to sound clever by using ante), is that it's a much better place to take blood from. If you're putting a cannula in it's useful to take blood at the same time, but later on if you have to do another blood test the cubital fossa is the best place because it's the least painful spot to have a needle. By comparison taking blood from the hand is much more painful.
        <blockquote>What a terrific post! And the pictures! Some tips I can use as well, I agree with almost all of it. I'm a little uncertain about the alco-wipe point, since I usually find rubbing the vein up and down a more effective method than tapping it (which I agree can be quite painful), but intuitively Shizzy's point seems correct so maybe in future I'll just rub down-ways and that might help me.</blockquote><br />
        <br />
        I figure any benefit you acheive by rubbing can be achieved the same by only rubbing down, and you get the added benefit mentioned. :) I never tap people really.<br />
        <br />
        <blockquote><br />
        The other useful thing about not cannulating the cubital fossa (if you're confused the cubital fossa and the antecubital fossa are the same thing and I think Shizzy's just trying to sound clever by using ante),...</blockquote><br />
        Haha :p antecubital is just the word that sprung to mind naturally. Both are correct.<br />
        <br />
        <blockquote><br />
        ...is that it's a much better place to take blood from. If you're putting a cannula in it's useful to take blood at the same time, but later on if you have to do another blood test the cubital fossa is the best place because it's the least painful spot to have a needle. By comparison taking blood from the hand is much more painful.</blockquote><br />
        <br />
        Agreed, most of the time, taking blood from the <span style="text-decoration:underline;">cubital</span> fossa is best. Less painful, easier to hit, and patients are use to seeing it get done there.
          Additionally:<br />
          The painful part is going through the skin. Yes, moving around underneath the skin will hurt but not as much. Go confidently through the epidermis because going slowly on that part is the part that really hurts. Slow down once you're actually approaching the vein.<br />
          <br />
          Hey and I never knew about the double flashback thing...although generally I just get in ;)
            I prefer kneeling to sitting on a chair, horses for courses.
            <blockquote>I prefer kneeling to sitting on a chair, horses for courses.</blockquote><br />
            <br />
            I don't think there's anything particularly wrong with kneeling or standing or bending, but I do think sitting down is a great way to create a consistent environment and thereby maximise your chance at success. Just like tennis players are very particular about things being exactly the same before every serve. It's a minor point, but I think it's useful, especially for the novice. Probably kneeling can create a fairly consistent environment as well, I guess.
            Essentially the point is to make yourself and the patient as comfortable as possible before setting out. Let's not over-think it, eh? ;)
            [offtopic]<blockquote>Essentially the point is to make yourself and the patient as comfortable as possible before setting out. Let's not over-think it, eh? ;)</blockquote><br />
            <br />
            Over-thinking is how I approach all my problems, I can't change now! [/offtopic]
            [offtopic]<blockquote><br />
            <br />
            Over-thinking is how I approach all my problems, I can't change now! </blockquote><br />
            <br />
            Ha. You'll learn to pick your battles in time. ;) Nonetheless, the original point is a valid one: being comfortable before you try cannulating <span style="font-style:italic;">does</span> make a difference, as opposed to hovering in an awkward position with poor lighting and access. Save that sort of thing for arrests, wherein you don't have the luxury of time, room and the option of sitting down. [/offtopic]
            Then again, I practise standing if it's likely to be an easy one. You will not have luxury to sit in an arrest. I also use bigger cannulas to practice with if I get the opportunity (eg if it's for a CT scan - you only need a 20g, but I will often use a bigger one if it's a decent vein anyway), because if someone is unwell and unstable and you're not used to using bigger cannulas while someone leans over you to perform CPR and people are shouting, you're going to struggle.<br />
            <br />
            Obviously wait until you're getting quite a lot in before practicing for emergencies though!
            <blockquote>Then again, I practise standing if it's likely to be an easy one. You will not have luxury to sit in an arrest. I also use bigger cannulas to practice with if I get the opportunity (eg if it's for a CT scan - you only need a 20g, but I will often use a bigger one if it's a decent vein anyway), because if someone is unwell and unstable and you're not used to using bigger cannulas while someone leans over you to perform CPR and people are shouting, you're going to struggle.<br />
            <br />
            Obviously wait until you're getting quite a lot in before practicing for emergencies though!</blockquote><br />
            <br />
            I agree, but I'm reminded that a lot of it is confidence and experience, so I'd recommend beginners make it as easy as possible before they try challenging themselves. Even in an arrest situation, while I don't have that experience, it makes plenty of sense to me that you would make every attempt to optimise your surroundings. This seems to fit that crawl before walking analogy that people like so much in medicine.
            <blockquote>Even in an arrest situation, while I don't have that experience, it makes plenty of sense to me that you would make every attempt to optimise your surroundings.</blockquote><br />
            <br />
            Can't say I've ever had that luxury. Arrest situations don't really allow you to do that - though it would be helpful in theory, in practice, you don't get that opportunity.<br />
            <br />
            WRT size of cannulae: whilst it's essential to be able to get 18g (etc) IVCs in, consider your patient's comfort and needs first. Don't be throwing in an 18 for the challenge when a 20 would otherwise do just fine - the bigger they are, the more they hurt (remember: first, do no harm). Similarly, in some circumstances, a 22g is adequate in adults - don't discount it entirely as an option.
            Today I used a cannula trick that I'm not sure has been previously mentioned. <br />
            <br />
            Asked by nurse to re-insert cannula in man because a couple of the nurses had tried with no luck.<br />
            <br />
            Issues<br />
            1. Patient needs cannula within 15 minutes for a scan and cannula needs to be at least 20G in the cubital fossa<br />
            <br />
            On examination:<br />
            Man presents with two 2x bruised arms and thrombosed veins from multiple failed cannulations. <br />
            Note a cannula in the dorsum of one hand<br />
            <br />
            Impression<br />
            Difficult, but not difficult enough!<br />
            <br />
            Management plan<br />
            1. Apply tourniquet to arm with cannula<br />
            2. Flush distal cannula with normal saline<br />
            3. Watch as proximal veins engorge <br />
            4. Cannulate like a pro just before your consultant enters the room wondering what the hold up with the scan is.
            One trick I picked up is to depress the skin slightly with the tip of the cannula (with a top down approach) so when you advance the needle forward it'll pretty much go straight into the vein. Cannot stress how important it is to torsion the skin properly before attempting anything to anchor the vein.<br />
            <br />
            When prepping the arm, always hang it below the level of the bed to let the blood pool to the extremities. Position the tourniquet close to the entry site, if you're going for the hand put it on the wrist/forearm.
      <blockquote>get the patient to pump their hand, tap on the vein (which, by the way, is painful when you have a tourniquet on).</blockquote><br />
      <br />
      what do you think of dangling the arm over the bed so gravity can work it's magic?<br />
      <br />
      Also, with regards to the cubital fossa, isn't it better not to cannulate there unless you have no other option (as its more likely to get kocked out, patient flexion and movement increases risk of infection to cannula site?)
        <blockquote>what do you think of dangling the arm over the bed so gravity can work it's magic?<br />
        <br />
        Also, with regards to the cubital fossa, isn't it better not to cannulate there unless you have no other option (as its more likely to get kocked out, patient flexion and movement increases risk of infection to cannula site?)</blockquote><br />
        <br />
        <blockquote><br />
        <br />
        <br />
        <ul><br />
        <li>Choose the right site and cannula. Before cannulating should have a pretty good idea of why you are cannulating and what kind of fluids/medications you are going to be giving through your cannula. It might be tempting to stick a little 22G in the antecubital fossa but this is useless for the patient who is going to be admitted for several days requiring IV fluids / meds. The antecubital fossa and hand are uncomfortable places for cannulas and frequently tissue or get yanked out. If you anticipate the cannula will remain in for a few days it is best to get access somewhere on the forearm. By now you should be aware it is best to save the antecubital fossa for bigger cannulas during emergencies (but if it&#8217;s the only place you can find it&#8217;s better than nothing at all!). The hand is an excellent place to cannulate if it is not going to be used for too long or if you need more convenient access (both cases apply to day surgery patients, for example).</blockquote><br />
        </ul><br />
        <br />
        I think shizzy covered, that second point pretty well, doctorbear. :) As for the first point re: gravity, yes it will help and may be worth doing.<br />
        <br />
        ***<br />
        <br />
        Since I've posted in this thread I've had a bit more experience cannulating during arrest situations or even once when the patient needed to be held down by 5 other doctors! I think all the usual principles remain the same. You should do everything you can to maximise your chances of success and, while that may not mean you are able to pull up a chair and feel super-balanced, it does mean that you're probably still better off trying not to get up caught up in the adrenaline of the situation and failing to get the cannula in because you were rushing.
          Can I belatedly add my thanks again for the thread (DEFINITELY at the over-thinking stage) and add my pitfalls and wins from my very early stage.<br />
          <br />
          - Check the equiptment on the trolley if you're in a different or new area, well before you consider agreeing to attempt a cannulla<br />
          - The importance of blueys can not be overstated<br />
          - Don't be a hero at the patients expense. Because I'm at the beginning of my training, I have the luxury of having a very low threshold for refusing to attempt cannulation. I know this isn't an indefinite option, and it's not a solution to "scared to try, ever", but it is worth pointing out that if you think a cannulation will be difficult, and is beyond your level, you can just not do it. <br />
          - Related: If there might be a reason no expect it will be tricky (bad veins, only one decent vein, or patient just told me they're hard to get blood from, or I'm just not feeling clever) I'll consider it, but I tend to nope out if that patient is very anxious or very miserable. No-one seems to mind (aloud)
    K
    • K
      koochkooch
    • March 19, 2014
    This is why I love this forum.
    tip/trick when doing it on kids and hoping they'll hate you less at the end of it all- about 20minutes beforehand make sure someone offers them a "magic patch". (aka emla application of some description to every area you might need to try at)..... potential to save the trauma and tears at least from a few if marketed well.
    E