This is an Intravenous
Regional Anesthetic block and this
is a block that's used for very simple procedures
in the forearm. So, things like removing little ganglia
from the wrist, doing median nerve decompressions,
this is a block that can be used. It uses
a double tourniquet technique. So there's
a Proximal tourniquet, which is near to the body,
a Distal tourniquet, which is away from
the body. You elevate the patient's arm,
after you've started an IV in that arm, you just
put a needle in and cover it at that point.
Elevate the patient's arm for several minutes and then you
use what's called an Esmarch bandage, which is really just
a big fat elastic. And you wrap it around
the arm very tightly to push all the blood
out of the arm. At which point you
inflate the distal cuff, so the cuff
nearest to the body. Take the tourniquet off
and then fill the limb, through
the IV that you've started with 0.5% lidocaine.
It's usually between 30-40 millimeters and
you can tell the approximate amount you're using
by just looking at the veins in the forearm. And if
they're starting to swell, then you've probably put
inadequate amount of local anesthetic in. You have to wait
probably 5 minutes before you get a good effect, but
that's usually time for the positioning of the arm and
the prepping of the surgical position. You have
to take the needle out of the hand at this point, and
then the surgeon can go ahead and do the surgery. If the patient
starts to have discomfort from the tourniquet at some point,
you can inflate the proximal tourniquet, which is
over tissue that has been blocked.
And once you know the proximal tourniquet is actually inflated,
you can deflate the distal tourniquet and the patient will
have instant relief from the pressure that
they had on their arm. This block is a very
safe block if you do it properly. At the end
of surgery, if it's been less than 30 minutes
since you injected the anesthetic, you should
wait. Do not deflate the tourniquet yet. Many
anesthesiologists believe that it's worthwhile
to deflate the tourniquet in a series of steps
to allow only a small amount of local anesthetic
to reach the central circulation, if
there is still a local anesthetic present in the limb
that hasn't been bound to tissues. So, you deflate
the tourniquet and reinflate it immediately again.
You do that 2 or 3 times over a minute or two, and
the local anesthetic is washed out of the limb.
And the sensation returns usually
within 4 or 5 minutes. So it's a pretty
short duration, once
the tourniquet's released. Intravenous
regional anesthesia is easy to do.
The only problem is that the surgical site tends
to be wet. Lot of local anesthetic floating around and
some surgeons find this annoying.
So local anesthetic toxicity
can occur with intravenous regional anesthesia,
particularly if the wrong drug or the wrong concentration
is injected. The only drug that is safe
in this situation is 0.5% lidocaine.
When Bupivacaine or stronger concentrations
of lidocaine have been given,
the spillage of those drugs into the central
circulation can cause serious side effects,
including cardiac arrest or seizures.
Finally, as I mentioned, many
anesthesiologists advice releasing the tourniquet
for 5 - 10 seconds and then reinflating, and repeating
that 2 or 3 times after
the surgery is completed.
So in summary, in this talk we've talked
about Regional Anesthesia and Analgesia.
We've spent some time discussing Epidural
or/and Spinal Anesthesia - Neuraxial Blocks,
and how they can be used for surgery or, in the case
of epidurals, how it can be used for labor analgesia,
or for postoperative pain control. We've talked
about various methods by which
peripheral nerves can be blocked,
with emphasis on ultrasound guided
techniques that have higher efficacy and lower
complication rates. And finally we
talked about Intravenous Regional Anesthesia.
The Pros and Cons of that technique.
And how it can be used for surgery
of minor peripheral