- In this video,
I'm going to be talking about the most important tool
that I've used over most of my 15 years
of injecting dermal fillers.
And this tool is a cannula.
And at the end of this video,
hopefully you understand why I use cannulas
and what is my favorite size cannula to use.
(upbeat music)
So I first started using dermal fillers utilizing a needle
when you first start learning dermal fillers
you do what's the status quo,
everyone use needles then
there was no real other choice,
they really imply that you should use needles
by packing a needle
within the box of filler.
To the needle they give you is
this tiny, short little needle.
It's in this case,
it's a 27 gauge needle
and you're meant to inject the whole face
with this tiny little needle.
You can see, wouldn't go very far.
I used to also be a trainer
for one of the main filler companies,
and I remember questioning
why we had to use this tiny little needle.
So I asked if I could use a longer needle,
we can see that's significantly longer.
It's more than double the length of this needle.
But they said no,
that you can't use anything
that's not in the pack.
You have to use whatever needle is in the pack.
And interestingly, they still provide
the same needle they did over 15 years ago,
in the pack with the dermal fillers.
So many years ago, I thought to myself,
why don't we use a cannula?
So cannula, which is what I have here,
has around tip, so it's blunt.
And that's got some huge advantages.
Interestingly, fat transfer
which has been done for an even longer period
than dermal fillers
has always really been done with cannulas.
And that has always been the way
that people have injected fat into the face.
But for some reason, when fillers came out,
they came out with needles,
and everyone was using needles.
One of the main key advantages
of a cannula over a needle
is that it is blunt.
So as you can see here,
you cannot penetrate my skin with a cannula.
Whereas with a needle...
No, I'm not gonna do that.
And the same goes with with blood vessels.
So you cannot penetrate an artery
or a vein very easily with a cannula.
So if you inject into a vein,
then the consequence of that is a bruise.
It's not great to cause bruising
that means is more downtime for the patient.
That's really one of the most feared side effects
of dermal filler injections,
is getting a bruise
an embarrassing bruise for two weeks.
But if you inject filler into an artery
that can have really serious consequences.
One of the most serious complications of dermal fillers
is when you inject a filler into an artery
that feeds the retina or the back of the eye,
and you lose vision in one side.
I'm not here to say that
it's impossible to get into a blood vessel, vein
or artery with a cannula,
but because it's blunt,
it's much less likely to penetrate
into that vein or artery.
That is the key advantage of using a cannula.
The other advantages include the longer length.
And now this is huge.
I imagine, if you have to fill various parts
of the face with a very short needle,
it's going to be multiple multiple pricks.
With the cannula, you can go in from one point
and reach many points along the skin.
This is particularly of importance
when you do an area like the lips,
if you use a very short needle,
you're going to be pricking
the skin multiple multiple times.
And of course, this causes more swelling.
And one of the other key advantages
of a cannula is that you can get a lot of feel,
for example, I need to know
what plane or what depth I'm in
when I'm injecting in the face.
So by using a cannula
I can actually feel which depth I'm at.
And for example, like around the eyes
a classic example, I know whether
I'm in the lower eyelid,
if I pop through the orbital retaining ligaments,
so there's a ligament
which sits like a hammock just under the eye,
and that sort of differentiates the cheek
from the lower eyelid.
So if I wanna inject into lower eyelid,
I know I need to pop through with a cannula.
If I'm using a needle,
I'll have no idea
because you won't get that popping sensation.
So there's a lot of feel
that goes on with a cannula,
whereas the needle slices right through everything,
you could be going into the wrong plane, the wrong depth,
but using a needle is significantly quicker
because it just cuts through everything like a hot knife
through butter, whereas a cannula you have to weave
and find your way through the right path
to get to your point where you wanna inject.
(upbeat music)
So what factors are they when choosing a cannula?
The first factor is the gauge.
So that's the thickness
or diameter of the cannula.
The greater the gauge,
the finer the needle cannula.
I remember this filler came out many years ago,
which was quite a thick volumizing filler,
and they actually gave you
an 18 gauge cannula,
which is a very big cannula to inject it with.
And in order for us to use that cannula
we were really need to use a lot of local anesthetic
in the face before using the cannula
because it was so painful.
I mean, imagine this thick cannula,
traversing through the tissues of the face,
and not only that,
the patients swelled.
They swelled so much,
and it was disastrous really.
And later on, we found out
that we actually didn't need to use the 18 gauge cannula
that came in the pack of that filler,
we could actually inject it
through a 25 gauge cannula.
I'm not sure why that filler companies have been
so inaccurate with the provision of needles
of cannulas with their packs.
Over most of my years of injecting,
I've been using a 25 gauge cannula.
For many years.
This was my favorite size until recently,
but I'll tell you more in a minute.
The gauge of a cannula theoretically,
also said to determine its likeness to a needle.
That is if you have a very thick cannula,
then it is less likely to behave like a needle.
If you have a very, very fine cannula
then, theory is
that it becomes more needle like in its property.
So there is an argument
that we should use bigger cannulas
to help reduce the risk of injecting into an artery,
especially in the light of the cases of blindness
that have occurred with dermal fillers
in the past few years.
The other property of larger and smaller cannulas
is their flow characteristics.
So a larger cannula will flow a lot quicker
than a smaller cannula.
So that is, you can inject a lot quicker
through a bigger, fatter cannula
than you can through a finer one.
Let me demonstrate.
In my left hand,
a 22 gauge cannula attached to five mils
of water in a syringe.
In my right hand I have a 27 gauge cannula attached
to five mils of water.
They're both the same length.
And if i squared as high as I can,
you can see that the 27 gauge cannula
on my right hand is a lot slower.
Oh, am getting the camera wet.
Than the 22 gauge,
that's finished already.
That doesn't flow very much.
So these are not fillers obviously.
I didn't wanna waste too much filler
like I did my previous video,
but the principles are the same.
This is Poiseuille's law,
which basically states
that given the same length, flow be inversely proportional
to the power of four.
So what you can (mumbles) is that
as an injector,
you will basically not be able to inject
as quickly with a finer cannula
than a thick one.
And of late that is changed my preference
for my favorite cannula
from a 25 gauge cannula to a 27 gauge cannula.
And the reason for this is
it's less traumatic,
there's less swelling to the patient, less pain.
And despite the fact that a 27 gauge cannula
is more needle like than a 25 gauge cannula,
remember the flow of the cannula is determined a lot
by not just how hard we press
but the gauge of the cannula.
Now it's human nature
if you can get something out quicker
because there's no limitation.
For example, with a large bore cannula
you're naturally gonna inject a lot quicker.
For example, if I were to use a 27 gauge cannula,
and I did accidentally perforate artery,
the rate of flow that I would inject
would probably be not great enough
to overcome the rate of flow of blood in the artery.
And that would reduce my likelihood
of injecting into an artery
and causing a complication such as blindness.
If you had a larger cannula,
although it's theoretically less likely
that you'll perforate an artery,
your flow rate is likely to be a lot lot higher
than if you use a very fine cannula.
So that would actually overcome the arterial blood pressure,
you would be able to inject into that artery
and flow that filler right up to the circulation
to occlude a structure such as the eye.
The additional fact the very fine cannula
is much less traumatic than a large cannula.
And the fact that you can
cause a low less pain and swelling
and be much more gentle.
The primary reasons why I use it,
but because also restricts my flow,
I am able to control my injection of dermal filler
for better aesthetic results
as well as less risk
of a significant injection
of filler into an artery.
I look forward to seeing you at our next video.
I think you might need a bit of filler here.
- Really, are you going to use the fine cannula?
Oh, that was your eye.