hi everyone this is lahiru from abc's of anesthesia and today we're going to talk about
valves in veins and why they're not a reason to fail intravenous cannulation so let's get started
so first of all let's go through how to identify if your vein has a valve in it and
this is actually quite tricky because you can't often see the vowels they're internal structures
but every now and again in a very thin person or someone with very little subcutaneous tissue
you might see a bit of a dilation in that valve or like what looks like a bit of an aneurysmal
dilation which is an aneurysm so just to show you what that might look like you might see a normal
vein like this and you might see a little bit of a bulging at one point that's usually indicates
a vowel now what do you do about this generally i'd stay away so maybe i would insert my cannula
going in just proximal to it aiming towards the patient or further down the vein enough
such that i've got enough distance for the cannula to fall in without approaching that valve i want
to make sure that the end of the cannula doesn't abut the valve that's pretty much it
i try to avoid it and if i can i go proximal to it and if not i try to go distal enough that the
end of the cannula doesn't encounter or touch that valve easy right now the next thing to ask
yourself is are you actually against a valve so just to reiterate imagine this is a vein
and this is the head and this is the tail end so you insert your cannula from here to there
let's say the valve looks like this inside the vein so occasionally you might not realize that
there's a valve there so you'll insert the cannula and you'll push up against here so you won't be
able to advance it any further and you'll know this because as you're pushing you'll notice that
you know you'll notice that you had all the other indicators that everything was going well
you had the first flashback you had the secondary flashback but at a certain point you're just not
able to advance the cannula you might see a tethering or movement of the vein as well and
that probably tells you that you may be up against a valve or you may or you may not be in the car
you know in the vein itself anymore so you'd have to check where you are just to make sure
i've got a video on how to check that your cannula is in making sure things like you know you can
ask for it you can flush the cannula you can you can you know you can see that there's a pulse uh
distilled so proximal to where you're flushing and a few other signs so the next thing we're going to
go through is what do you do if you are up against a valve so let me draw that again so that's your
vein that's your valve now the first thing to do is if i've got my cannula up against the valve
that's imagine that's the plastic cannula all i need to do is pull back a little bit and that way
i know that i'm still in the vein and i check to see if i can flush fluid in the right direction
now the next thing i do is i make sure all of my other things are going well for example
i got the first flashback i got the secondary flashback inside the cannula itself so the
first flashback was in the in the cannula needle chamber second flashback was in the cannula lumen
i'm then able to push the cannula and feed it off really easily without any tethering and without
any resistance and finally i can flush saline through that cannula and notice that there's a bit
of a pulse or pressure at the appropriate spot on the vein you know proximal to where i was flushing
so as long as those things are present and maybe i can aspirate blood that's a reassuring sign but
not always possible in the smallest veins so if that is all good i can withdraw the cannula a tiny
amount and then check to see if it works again now i'm going to say this with the proviso that maybe
you don't want this cannula to be in that vein for a long period of time for example in anesthesia
sometimes the case is only going to last 10 15 maybe 30 minutes and that would be reasonable but
say i've got a very long case or this patient's about to go into the ward i don't really want
extra cannula bits to keep sticking out of the skin because maybe that's an infection risk so
again look to your local hospital policies to make sure you're doing the right thing
but imagine in a really difficult venous access patient this may be your only option and it's very
reasonable to use that cannula for a short period of time again follow your hospital policies with
that now there's one other thing to be cautious of imagine that you put the cannula in quite close to
where the valve is that means that if you were to pull back on this cannula there may not be enough
cannula in the vein for you to be certain that that cannula will stay there so any movement of
the patient's arm or hands or something else maybe just the you know time will cause this cannula to
potentially come out of the skin and that would be incredibly dangerous imagine giving fluids or
drugs very important drugs into the subcontinence tissue would be very very bad so you want to be
really you want to be really really cautious with this now the final question i get asked is can you
just push through this valve now say you know as a general rule please don't try that now in
my experience i've been able to push through valves very very occasionally um but i would
suggest that there's also risk of it so sometimes i've been successful in pushing through a valve
but i haven't done it in the last 10 years or so because i don't think it's the right thing to do
but also that there is a chance that you might traumatize the vowel for example if you're up
against the valve and you try to push through maybe you're successful but other times i've seen
where you know there is trauma caused to this whole vein and you might actually cause rupture of
this whole vein and that's far worse because now you may not be able to use other parts of the vein
say proximal because you cause too much trauma there so as a general rule don't try to push
through that valve so i hope you enjoyed that video again i don't think valves are the reason
that you miss or fail an iv cannulation but you have to treat it with respect and only use
they can use these cannulas for potentially short periods of periods of time and always be cautious
that there's enough cannula lumen actually in the vein to make sure your drugs and fluids
are getting delivered to the right side thanks very much for watching