hi everyone this is lahiru from abc's of anesthesia
and today i'm going to go through a bit of a novel technique for blood
collection
now obviously cannulation is something that i do time and time again and often if i need
to take blood i'll still insert a cannula and i'll take blood with that because i find that
a cannula is just a plastic device that's inside the vein there's no risk once the cannula is in
there's no risk of a needle rupturing inside of the vessel especially if it's a very difficult
cannulation or very small vein now my novel technique is really just to do that cannula
but backwards now i want to stress that this is a really advanced technique so it's something that
i don't see many people doing but it makes a lot of logical sense if you want to attempt this
please do it under supervision and only with the consent of the patient and your supervisor this
is a bit of a novel technique the reason i came up with this technique is because a lot of the
time i get called to do bloods when it's most difficult and this is often the only option i
have for taking blood now i want to go through that in a bit more detail so imagine a vein
on my patient's hand right now blood is flowing in this direction normally what we do is we
insert a needle in this direction what that does that needle ends up blocking most of the flow of
the vein and so it's going to be very hard to take a good quantity of blood because the
flow has been decreased now what i'm suggesting that we do is because blood's flowing just this
direction why don't we insert a cannula or needle backwards that way all that blood all that venous
return goes straight into the cannula without any obstruction at all so what i'll start with is a
lot of the same things i'll put the tourniquet on just to try and improve my vein selection
and as you can see i'm getting my position very different to a normal cannula because
of the trajectory because i'm going backwards i'm trying to find a vein
and i've got a nice good action across you know my body that's you know feels very normal again
there's an advanced technique so make sure you're really comfortable with cannulas and
appropriately supervised for this so i've chosen this vein across here so i'm just
going to swab with alcohol cloxidine ensuring the patient has no allergies to this
all i need to use is a small gauge cannula for this so a 22 gauge is absolutely fine
and my technique is slightly different my tension on the skin will be going you know distally this
time again low angle of insertion
getting the flash back leveling out advance a few millimeters
and already i can see that there's going to be a good flow of blood back so what i do then
is i can go straight on with the syringe or place an iv bung on here just like that
and this probably makes a lot of sense now what i have is a blood flow back from distal to proximal
and so my cannula is taking all of that blood very easily and you'll notice now sometimes you
get enough pressure that you don't even need to aspirate on the syringe but in this circumstance
i do but that's aspirating blood at a rapid rate as if i was actually taking it from a large
cubital fossa vein so that's fantastic so i won't take too much of my friend's blood here
and then i can always flush now if for any reason you need to sample
some blood more frequently you can always keep this in for the appropriate amount of time
ensuring again that all your protocols are followed from your local hospital
so that's a novel blood taking technique with a cannula it's the reverse cannula technique
and again i find it so useful especially those for those tricky patients with very tiny veins
where i need absolutely everything to go right for me to collect blood thanks a lot
you