So we're now going to talk
about my nightmare
and the nightmare of virtually every anesthesiologist.
And that's the failure to secure the airway, because
this can lead to death, can lead to immediate
cardiac arrest, and it can lead to permanent
brain damage, chronic vegetative
states, from cerebral hypoxemia.
This is the single most important aspect
of the anesthesiologist's job.
And really, it's what we get paid for.
If we fail in this respect, we failed in every
respect, because obviously, if the patient doesn't survive
the anesthetic, having surgery is kind of
a waste of time. We're going to talk more
about standard intubation techniques
and techniques used in the difficult airway
situation, in Lecture 5, under General
anesthesia. But some of the warning signs,
just to give you a preview of what's going to happen,
include poor mouth opening; normally
a mouth should open 5 - 6 centimeters, but
if it only opens less than 2 - 3 centimeters,
that's a warning sign. Poor neck mobility. So,
the inability to extend the neck
is a major concern and
it's common in elderly people.
So we see it a lot. Small or deformed
mandible. This can happen in congenital anomalies,
it can happen with damaged mandibles, it can happen
with people who have very poor dentition,
and have a large overbite and a poorly
developed mandible as well. We mentioned
we measure the mento-thyroid
distance, which is the distance from the tip of the chin
to the thyroid cartilage, which is the large cartilage in
the neck, the airway. And if it's less than 4 centimeters,
we know we may have a problem.
Short, thick neck can be a problem.
Fixed flexion deformity of the neck,
as seen in some diseases such as ankylosing spondylitis,
and anything that interferes with normal
airway throughput, such as a tumor,
an abscess or hematomata, can all lead
to difficult airway situations. Most anesthesiologists
take the view that we should always
be conservative when approaching the airway.
And if there's any doubt that we
can get a tube in, in the patient, asleep and paralyze,
then we shouldn't put them to sleep, and we shouldn't paralyze
them. We should do an awake intubation. Now,
awake intubation sounds like a terrible technique,
I can just see all of you gagging, and thinking all kinds
of horrible things about the person who would subject
you to this. And it sometimes isn't very pleasant,
I'll be very honest about it, but it is the absolute
best way to prevent failure in intubation.
Because the patient is awake and maintains
his or her airway through the whole
procedure. So basically, if you
are concerned about getting a tube in, or you think
it isn't going to happen, then you should definitely do
an awake intubation. There are other
techniques that allow us to make
somewhat difficult intubations easier.
And these include airway adjuvants available
to use immediately. A stylet,
which is a malleable device
that goes through the tube and gives the tube shape.
A bougie, which is an even longer device which also can
be passed down through the, through the cords, even
in a situation where it's very, very difficult to see the cords,
and then the tube can be passed down, the endotracheal
tube can be passed down over the bougie.
Video-laryngoscopes actually allow us
to use a screen and see exactly
where we are. The laryngeal mask
airway is a device that allows
us to, in certain circumstances, intubate
through the LMA and secure the airway
that way. And then, if worse comes to worst,
we have to do a surgical airway. And for that
we need to have a crico-thyrotomy kit immediately available.
And most of us dream that we'll never do this, and
as of this moment, and I'm pushing my luck here,
I have not had to do this.
You should always keep 'difficult intubation' kit
immediately available in the operating room area.
It doesn't have to be in every operating room, but it needs to be nearby.
And you need to have a portable kit, because anesthesiologists
get called all over the hospital to secure
airways in people that other people
have, other physicians have failed to secure. So,
emergency room, tents of care unit, cardiac arrest
on the wards. We get called to these on occasion simply
because our colleagues and other specialists have failed
to intubate the patient. There's
a “difﬁcult airway” algorithm. Most
Anesthesiology Societies have
a 'difficult airway' algorithm.
The American Society of Anesthesiology has a very
extensive one. The only negative thing I can say about it
is, it's probably too extensive, it's hard to memorize.
The Canadian Anesthesiology Society
has a very simple algorithm. It may be too simple.
The UK has the Difficult Airway Society,
which is a society that is devoted to coming up
with better ways of dealing with difficult airways.
And one should definitely look at their web page
and be prepared to deal with a difficult
airway. So if, be prepared in any
difficult airway to call for help,
and to call for help early! Get people in there to help you.
Because, if you don't call for help, and you
get into a situation where you cannot intubate
the patient, you may be responsible for that patient