hi everyone today i'm going to go through laryngeal mask airways
also known as lmas or supraglottic airway devices
i'm going to go through how to place the lma and also all the ways we can optimize and troubleshoot
when things go wrong and also give you a context of how to use it so let's get started [Music]
so the first disclaimer obviously patients who are hypoxemic or not ventilating well these are
high risk situations and the lma again falls in the context of a whole plan for resuscitation
so first of all i like to give like with all my talks a strategy and a framework for the way that
i'm going to be approaching this so i imagine that airway management is really trying to optimize
oxygenation ventilation through any of these means bagmas ventilation intubation we've got a couple
of videos for that as well as the lma now if these aren't working and we're in a can't intubate can't
oxygenate scenario then you'll be thinking of a surgical airway or front and neck access which is
a whole other topic as well and you'll definitely need to be calling for help and only doing things
that you're comfortable doing and know how to do it and also manage the problems and complications
that could occur so with that in mind let's get started with lma ventilation so a laryngeal mask
airway is really a device that just sits over the trachea and the laryngeal opening and this then
creates a seal which allows us to positive pressure ventilate so again just like the bag mask
or intubation you're what you're doing is you're creating a seal with a certain structure and then
using positive pressure to ventilate through this tube and inflate the lungs so what i'm going to do
is i'm going to demonstrate on this airway levy model so again where i'm going to place this lma
really is just sitting past the tongue with the opening in aperture just above where the cords are
and that way you'll get ventilation down this tube and into the airway the lma that i just
showed you is a first generation or classic lma now the second generation lmas pretty much have
a couple of different things going on one of the main things is they have a gastric port so this
is a pro seal you can see a gastric port there as well as the aperture where you can ventilate from
same with the supreme lmas which i'll show you in a bit more detail later i've got a gastric port
there as well as a normal airway ventilating port now the eye gels which we have on our recessed
trolleys in our hospital also have this little gas report again at the tip having this extra gas
report means that you might be able to identify regurgitation as it happens and then manage it
by putting a nasogastric in or in alternatively intubating the patient so next we're going to
go through is insertion technique now that you've seen where the lma sits in that anatomical model
you can probably make sense of what you need to do so essentially there's a couple of different ways
that you can insert this lma but the most common one is to push it past the tongue straight back
so what i do is i usually open the head just like that so do a head tilt that opens the mouth often
you can get your assistant to just open up the mouth like so and that allows you to place this
in you need the minimal aperture that you need is about two centimeters so just remember that if
you have a patient with very small limited mouth opening you you'll need a low profile potentially
like a fast track lma to make sure that you're able to get it through to 270 is probably the bare
minimum you need so i've got the mouth open i push it back now the first resistance you're going to
get is the tongue so you really sometimes you get a resistance there that doesn't allow you to place
it so what i have to do is i just need to apply a light bit of pressure and that then sits correctly
and you'll feel a bit of a pop and a rise in the larynx as that goes down so just to demonstrate
that insertion again i tilt the head back i might get an assistant to open the mouth or even try to
open it myself i push it past the teeth gently and then i'll push backwards so it goes along
the upper part of the hard palate and then down the soft palate past the tongue again sitting
just above the airway the trick here which allows ventilation again as always i check ventilation
you can see the rise and fall of the chest and sometimes that's all you need
other times you'll inflate the cuff [Music] and there's it's already got some zones marked out
essentially you want to inflate that cuff and try to create a better seal
so one of the common things that happens is that as you place the lma in sometimes it just gets
stuck at the posterior pharynx so what you need to do is sometimes follow the curvature of your hard
and soft palate and then push it around the tongue so i'm actually forcing backwards with a bit of
pressure and that allows it to get past the tongue more easily that's one of the first things i do
again there's many ways this can go wrong so really no matter what you're doing you
have to continuously assess that you're ventilating so rising for the chest and that
you're getting fogging in the tube and hopefully entitled co2 trace as well as the saturations
are appropriate and safe for this patient so let's say you're trained to put an lman and you've put
that lma in and you're trying to ventilate this patient but you simply can't ventilate
for example there might be an obstruction or it might be too great a leak so i've got a few things
that i can do and as i mentioned a few my other videos the common things are i could position
the patient better or i could provide paralysis again paralysis can be very tricky you've got
to know how to manage the complications of paralysis before giving any of these very
dangerous drugs so positioning paralysis of ways i can optimize any of these airway situations
that's specifically for lmas just like with having a mask on your face or an entry kill tube the size
and the type are mainly the things that i congest so this one i've got as a size four if there's
too much of a leak i can either use a size five elements to go up in size or put a bit more air
in the cuff generally speaking you want to go for a higher size and put less air in the cuff that
just minimizes the chance of trauma to the airway now the type of lma is also an interesting thing
so when you when we looked at studies of lmas in action the classic lma this one that you see here
had a 93 or so percent first insertion success rate where some of the second generation only had
maybe above an 80 success rate first time however with three attempts that rose to a hundred percent
in most of these circumstances so just know that the classic lma is actually a really effective
device um and the other second generation elements are really quite effective as well but each lma
type may have its advantage and disadvantage so if it's not working for me if i've got a leak
i'll definitely move up in size so if i've tried a different size lma it just doesn't seem to fix
the problem i can then try a different type of lma whether it's a pro seal or supreme or an igel or
one of the newer devices that will be out in the market now one of the other troubleshooting steps
i do is do micro adjustments so this is something you may have not heard of before but let's say
i've got an lma that's just not working perfectly adequately i might just do these micro insertions
up and down of the lma and i might even just tilt the head back and forth just to find if there's
an optimal position now as i'm talking about optimization steps for lmas just know that unlike
bagmas ventilation repeated attempts in an lma can cause harm so when i think about this really a lot
of the guidelines out there say that you should have maximum two or three attempts at inserting an
lma if it doesn't work in two or three attempts go back to bagmas ventilation because multiple
insertions of the lma can cause trauma and one of those things that national audit project studies
reported and these were big studies showing data about airway problems it showed that repeated
attempts at intubation and lma insertion could cause trauma to the airway and make a manageable
airway and impossible to manage airway that means that trauma to the airway could cause swelling
which means that now instead of just being able to go back to bag masking and safely manage a patient
now i have an obstructed airway which is that can't intubate current oxygen airway
so again don't have repeated attempts if you're failing each time a maximum of two or three times
is all you want to do if that fails go back to bag masking and as always call for help and assistance
now the final situation that i would use lmas in context would again be referring back to the
difficult airway society algorithm and guidelines and the vortex approach so if i've got a situation
where i've got a patient i'm giving an anesthetic to and i've got an unexpected difficult airway
i've tried back mass ventilation i've optimized adele nasopharyngeal two hands jaw thrust and
everything and i can't auctionate i try to get a view with the laryngoscope and it's a great
full view and i don't have maybe a video language language scope handy or it's on the way i would
then put in one of these lmas as my rescue device so again i'm just trying to maintain oxygenation
while planning for other things planning for another operator with maybe a video laryngoscope
and an engineer intubation or front and neck access so remember all of these techniques are
really important to learn in context so i just want to go through some of the key differences
between the classic lma and the second generation lma so there's quite a few second generation lmas
including the igel the supreme and the pro seal and they'll probably be more in the market as
well there's another airway device also called the fast track which is purpose built to be able
to intubate through now this classic lma again really is this airway tube then an inflatable cuff
and an aperture there by which you can ventilate the second generation lmas have a few different
features to them generally speaking the second generation lmas have a gastric port
which is this one that we've shown before and that sits often at the tip of the lma and leads out
they often all have a bite block here so if you can see with the eye gel this is a really firm
structure here and it's roughly sitting at this line so where your teeth are at that line it's
a very strong plastic which means if the patient bit down they can't obstruct here which is really
important if you have an extracted tube that's you know obviously a real problem for ventilation
same with the supreme device it is pre-formed and it sits with the teeth along this aperture here
and again that's very hard plastic so the final thing that makes second generation potentially
more useful than a classic lma is the fact that they can generate higher pressures for ventilation
so the classic lma 20 centimeters maybe 30 centimeters water maximum pressure for insulation
whereas these devices can potentially go 20 above that and sometimes even up to a total
of 60 centimeters water so generally speaking with the eye gel with the supreme of the proceed
leaven you'll get high insulating pressures some numbers quote anywhere from 40 even up to 60
centimeters of water now this is not always the easiest thing to do now there's always
a problem so for example if i'm generating that much pressure there's always the risk
that i might insufflate the stomach which means air in the stomach causing increased pressure
in the stomach and that increases my risk of aspiration as well so even though i'm able to
generate higher pressures to ventilate this is not always the most advisable thing to do and again
um i'll be using this in emergency situation if i'm going to be generating high pressures
so imagine that now in the recess context that's why these second generation lmas are actually
quite a useful device i've got a patient who's unfasted and deteriorating on the ward outside
of a theatre or a critical care environment i really want a device that potentially people
who aren't as trained in intubation can still do and still insert pretty safely so now if i use a
second generation lma like the igel it's pretty easy to insert i can use high pressures because
occasionally the patient might be sick with sick lungs obstructive or restrictive lung disease
or obesity so i can generate higher pressures to create some safe ventilation oxygen
oxygenation but also if the patient's unfast and they do regurgitate hopefully that regurgitant
liquid will go through that gastric tube and then give me an indication i'll also be able to put
a small nasogastric tube through there allowing me to drain that stomach so there's a few advantages
with the second generation lmas now these aren't necessarily borne out in studies it makes good
sense that they would provide an advantage but take really large numbers in randomized control
trials to prove absolutely definitively that this is the case so what i'm going to do is
using the igel i'll demonstrate where it sits in this anatomical model we've got the gastric port
just there what i do now is as i place this in this gastric port will sit and hopefully block
the esophagus so that it prevents any aspirant or aspirational gastric contents going up into the
posterior pharynx and potentially being inhaled causing an aspiration injury with the other ones
as well so here's the supreme lma again a similar design it's got a gastric port as well as a normal
ventilation port and that again sits in the proper place blocking off the gastric the esophageal
opening and this will be that gastric port there pro seal one of the first second generation lmas
again you can see that gastric port there and that sits just above the esophageal opening and then
you can see where the ventilatory port sits now this has quite a large drain tube so it probably
makes it easier to use the nasogastric tube to drain um the stomach if it needs to be drained
again the same technique simply tilt the head back open the mouth and then i'm pushing it down and
following that curvature around the back there the agile doesn't require insufflation this structure
here simply sits there and molds to the right position again the supreme very similar technique
place it and then i might inflate the cuff to make sure that it's working adequately
now this is the pro seal again similar technique often you'll find that this comes
with an introducer so what i'm going to do is the variation of the technique the introducer provides
this flexible lma with more structure but in the correct situation and gloves on and you know
providing all that proper hygiene i can insert it past um without needing the introducer so thanks
very much for watching there's abc's of anesthesia we've gone through lmas the optimization the
strategy how to troubleshoot and kind of the reasons for different styles of lma so i hope
that was interesting please share with anyone who might be interested i'll see you next time
[Music] you