00:08
So there are many Other
Regional Blocks and virtually,
every portion of a limb can be blocked
using a regional
technique. So, it's possible to do multiple blocks
on the upper limb and multiple blocks on
the lower limb. The way we used to do this,
the way I was taught to do it, was
to feel for an artery, the assumption
being that the nerves to a certain area were
closely in contact with that artery, pass the needle
towards the artery until the patient
complained of an electric shock going down their arm
or down their leg. Obviously, not a pleasant experience.
00:48
At which point we would inject. The problem
was that it failed a lot of the time.
00:54
And if you actually got too close to the nerve and pierced
the nerve, causing that paresthesia, that electric
shock feeling, you could actually damage the nerve.
And because we weren't seeing where the needle tip
was going, even though we were trying not to hit the artery
that we were palpitating at the same time, it wasn't unusual
to hit the artery and for hematoma to form
in the area. So it really wasn't a very satisfactory
technique. And many of us, essentially,
stopped using regional blocks
for upper limbs and lower limbs because
of that problem.
01:28
For the past 20 years,
the use of the nerve stimulator to identify
the nerve position has been popular and successful.
01:34
But still not as perfect as I'm going
to show in a moment. With a nerve stimulator you start
with a low current.
01:41
The stimulator is set 1 milliamp
and you advance it towards the nerve,
and you watch the patient's
and you advance it towards the nerve,
and you watch the patient's
muscles to see if there's a twitch that goes along with
the nerve you're trying to block So what you'll see
is this kind of thing. And, as you get close to the nerve,
you turn down the current but you try
to maintain the twitch, and you try to get as close
to the nerve as you can, at the lowest possible current,
less than 0,5 mA, at which point
you inject the local anesthetic.
02:13
Again, the whole procedure is blind, other than
the fact that you're putting a current in and
you can see some movements in the limb. You can't actually
see the position of the nerve. You can't see the position
of any arteries that might be in the area.
Over the past 15 years, a technique
developed by Vincent Chan in Toronto, has been
widely accepted by anesthesiologists
and this has really changed
our mode of delivering
regional anesthesia and has improved the outcomes
dramatically. This is called ultrasound guided
needle placement. And basically what it is,
is using ultrasound to identify
vessels and nerves, and then passing a needle
through tissue, watching the needle
with the ultrasound until you're very close to the nerve,
and then injecting the local anesthetic
at the nerve. And you can see all this using the ultrasound.
But, as you'll see in the video we're
going to show you, it's not as easy to see as
you might think and it does require a significant
amount of training and practice to become good
at it. The good effect of this though has been
that the success rate of regional analgesia
and anesthesia has improved dramatically. And this
has really improved care, particularly for patients
having shoulder surgery, upper limb
surgery, and lower limb surgery.
A lot of the technique has led
to excellent post-operative pain control, which
we didn't previously have. Now we'll watch
a video an ultrasound guided femoral nerve
block. So this is an ultrasound guided
femoral nerve block. And the large black object
in the right upper corner, it's just disappearing now,
is the femoral artery. And the way you know this is
an artery is that, when the anesthetist compresses
the tissue, the artery is not completely compressed.
And this is a large artery, so you can actually see
it pulsating. The anesthetist is now
going to pass the needle from
the skin, in a lateral fashion, down towards
the artery. It's easy to see the shaft
of the needle, but it's much more important to see the tip
of the needle. And sometimes it's difficult to see the tip.
04:31
That ultrasound opaque object that
the needle tip is up against now is
the femoral nerve. You do not want to enter that nerve.
If you enter it, the patient will complain of severe
pain or you'll notice when you try to inject
local anesthetic that you can't. So back
off from that if it occurs. But with ultrasound, once
you learn how to identify the tip, you can go very, very
close to the nerve. So you can see this tip, is
right up against the nerve. And in just a moment
we're going to actually be able to see the local
anesthetic being injected there. You can see
that little shadow that developed. And the local
anesthetic surrounds the nerve or at least
forms a pocket at the base of the nerve. And within
a few seconds, the patient starts to lose
sensation along the distribution of that nerve
and the needle can be removed. Now, this
portion here, the anesthetist is going anterior
to the nerve, whereas the previous injection
was posterior. They want to put a local anesthetic
around the nerve, so they're going to inject anterior to
the nerve as well. So regional anesthesia has improved
dramatically with this technique that was introduced by
Vincent Chan in Toronto.