Ep. 20 - Out of Hospital Airway Adjuncts: King Tube vs LMA

King Tube vs IGEL for Airway Management

In this episode of Wilderness Medicine Updates, Dr. Patrick Fink addresses a listener's question on whether to use a King Tube or an IGEL as an out-of-hospital airway adjunct. The episode begins with an overview of airway management techniques from mouth-to-mouth resuscitation to supraglottic airway devices. Dr. Fink explains the benefits and drawbacks of various airway adjuncts, including oral and nasal pharyngeal airways. The discussion then shifts to a detailed comparative analysis of King Tubes and IGELs based on retrospective and prospective studies. Dr. Fink evaluates the evidence indicating that IGEL may be more effective and easier to use than King Tubes, particularly in pre-hospital cardiac arrest situations. The episode concludes with recommendations for pre-hospital providers and an encouragement for listeners to share their questions and feedback.

Links:

iGel LMA

King Tube

Smida T, Menegazzi J, Scheidler J, et al. A retrospective comparison of the King Laryngeal Tube and iGel supraglottic airway devices: A study for the CARES surveillance group. Resuscitation. 2023;188:109812. doi:10.1016/j.resuscitation.2023.109812

Smida, Tanner & Menegazzi, James & Crowe, Remle & Scheidler, James & Salcido, David & Bardes, James. (2023). A Retrospective Nationwide Comparison of the iGel and King Laryngeal Tube Supraglottic Airways for Out-of-Hospital Cardiac Arrest Resuscitation. Prehospital emergency care. 28. 1-13. 10.1080/10903127.2023.2169422. 

Lønvik, M.P., Elden, O.E., Lunde, M.J. et al. A prospective observational study comparing two supraglottic airway devices in out-of-hospital cardiac arrest. BMC Emerg Med 21, 51 (2021). https://doi.org/10.1186/s12873-021-00444-0

Chapters

00:00 Introduction and Listener Question

00:55 Understanding Airway Adjuncts

02:12 Basic Airway Management Techniques

06:34 Advanced Airway Devices: King Tube and LMA

11:35 Comparative Studies on Airway Devices

17:35 Prospective Data and Final Thoughts

25:24 Conclusion and Listener Engagement

As always, thanks for listening to Wilderness Medicine Updates, hosted by Patrick Fink MD FAWM.

Connect with us by email at [e-mail].

You can pay us a compliment and share the show with a new listener on any popular platform here.

Episode Transcript

Patrick (00:07):
hello and welcome back to Wilderness Medicine Updates
the show for providers at theedges.
I'm your host, Dr.
Patrick Fink, and today we'regonna talk about out of hospital
airway adjuncts.
This comes from a listenerquestion.
I want to say thank you to TomHuck, who wrote in with this
question from the Black ForestMountain region in Germany.

(00:29):
With a question about whetherthe team that he volunteers with
should be focusing on using theKing tube.
We'll talk more about what thatis shortly, or the LMA and
whether there's any evidence tosupport the use of one or the
other.
And thankfully, there are somegood studies to guide our
thinking on this.

(00:50):
So let's jump right in.
To begin with, let's do a littleintroduction where we talk about
what I mean when I say an airwayadjunct.
So I'll march you through how Ithink about providing
respirations in the pre-hospitalenvironment.
I see there exists a spectrum,and this spectrum spans from

(01:15):
mouth to mouth resuscitation,yuck, all the way up to anything
which involves the use of anendotracheal tube.
So that is intubation,cricothyroid, otomy, where there
is what we would call adefinitive airway or a tube
inside the larynx, a hundredpercent.
If we put air in that tube, it'sgoing in and out of the lungs.

(01:37):
So at the lower end of thespectrum is the potential for
providing mouth to mouthrespirations to someone who has
insufficient or absentbreathing.
To my mind, this is completelyoff limits within the
professional context because itis an unacceptable level of
exposure to body fluids.
There's just no body fluid, bodysubstance, isolation happening

(01:58):
there.
This is something I would dofor.
A close friend or family member,but in the professional context,
I would never do it.
And the second reason I wouldnever do it is because I'm
always prepared to avoid thissituation.
So that brings us to the truebottom floor of pre-hospital
airway management, which is theuse of a ventilating mask.

(02:21):
This is a CPR type mask.
It's roughly the shape of acupped palm.
You can place it over the mouthand nose.
And anyone that is worth itssalt has about a, I would say
centimeter and a half diametertube, which leads in and out and
has a one-way valve on that.
That lets us breathe air into apatient.

(02:43):
It lets exhalation go out adifferent way, and thus, if the
patient were to vomit while weare providing respirations, that
vomit does not go into ourmouths.
Yuck.
But this is pretty inconvenientto use just this mask because
we're having to bend all the waydown right up next to the
patient's mouth if we're tryingto provide other interventions.
At the same time, it's justchallenging to manage.

(03:05):
So this might be what I carry inmy pocket when I'm skiing around
working as a ski patroller, orwhat I carry in my backpack when
I'm ski touring.
But if I'm thinking about anydegree of prolonged care or
resuscitation, the next thingthat I'm gonna add to that is a
bag valve mask.
So the mask for a bag, valvemask is the same as a CPR mask,

(03:25):
but we add to that a bag.
It's roughly the size of anAmerican football, a rugby ball.
It's soft.
When we hook that up to our maskand we squeeze it, it provides
ventilation, it squeezes thatair into the lungs.
It gives us some additionalbenefits.
It can come with some bells andwhistles.
The main benefit is that you cansqueeze it with one hand.

(03:48):
You can be doing other thingsprovided that that mask is
secured to the face by someoneelse.
The other benefit is that it canhave a pressure meter on it, so
you ensure that you are notsqueezing too hard, and it may
also have a peep valve or apositive and expiratory pressure
valve.
Basically, this says how muchforce can come back out, and

(04:09):
this can help us keep the lungsinflated in between breaths.
So I love a peep valve,particularly on people who are
overweight, have a lot of chestwall.
Pressure or tissue, um, or mayberesistant lungs if we're
treating someone who has asthmaand we need to help stent those
airways open.
That peep valve is a simplescrew down device that lets me

(04:30):
choose to give five, maybe 10rare cases, maybe 15
millimeters, mercury ofexpiratory pressure.
So that's the standard bag valvemask, and it's ubiquitous on
ambulances and in rescue kitsand throughout hospitals,
everywhere.
The next layer that I would addto that are where we really get

(04:50):
into, we would call an adjunctor like an add-on, and those are
the oral pharyngeal airways andthe nasal pharyngeal airways.
Oral pharyngeal airway isbasically a fancy curved
popsicle stick, which you canslide into the mouth.
It helps hold the tongue forwardso it's not sliding backwards
and obstructing respirations.
It makes it easier to bag thatpatient with the bag valve mask

(05:13):
the nasal pharyngeal airway.
Is essentially just a latexrubber tube which slides into
the nose and gives us the samebenefit that it stents open the
air and allows air to travelinto the posterior oropharynx
without the resistance of thosetissues.
These are great tools becausesomeone who is unconscious is
all relaxed and is trying tosnore, collapse their airway.

(05:37):
Make it as hard as possible foryou as the rescuer to provide
effective ventilations.
So we can add an oropharyngealairway, a nasopharyngeal airway,
into our unconsciousunresponsive patient used with
the bag valve mask.
It's now easier to ventilatethat patient.
But what if that isinsufficient?
Either we're having troublemaking air go in and out using

(06:00):
those tools, or there'ssomething else that makes us
worried about the patient'sairway.
A couple different reasons thatthat could happen.
This is not a comprehensivelist, but say the patient is
vomiting and we're worried aboutvomitus going from the esophagus
down into the lungs.
Bad situation, aspirationdoesn't work well with
ventilation, or perhaps thispatient is going to be subjected

(06:22):
to a prolonged transport, andthen we want to have something a
little bit more secure that isharder to dislodge and we don't
have to be constantly reapplyingthat mask to the face every time
we want to give a ventilation.
So the next step up from a bagvalve mask with adjunct like
oass and NPAs becomes what Iwould call a supraglottic

(06:43):
device.
And that blanket categoryincludes laryngeal mask,
airways, everything from anintubating LMA to an IGEL.
It might include a combi tube ora king tube.
And these are essentially toolswhich.
Try to direct the ventilationfrom the bag valve mask more

(07:03):
directly through the vocal cordsinto the trachea.
They are not what we wouldconsider a long-term definitive
airway because they don'tactually enter into the airway.
There's no a hundred percentguarantee that the air that you
put in there is gonna go intothe lungs.
But they do a much better jobthan a simple bag valve mask at

(07:26):
protecting against things likeaspiration from vomitous and
people who are difficult toventilate with.
The bag valve mask alone can bemuch easier to manage with one
of these devices in place.
The two devices that we're gonnatalk about today are the king
tube.
And the LMA, so I'll break thosetwo down.

(07:49):
To start with, the king tube isessentially a long plastic tube,
which has two balloons on it,one at the end, and one a few
inches up from the end.
This tube is inserted blindlyinto the esophagus and you
inflate both of the balloons.
And the idea is that then theballoons are above and below the

(08:12):
laryngeal opening.
Between those balloons is wherethe air port is, so that if you
push air in and out of the kingtube or the combi tube, that air
is going to be delivered to thearea around the vocal cords, and
the balloons above and belowwill exclude contents from the
trachea and will also seal offthe outside world so that your

(08:32):
pressure can be delivereddirectly to the trachea.
These were really popular for along time.
It's relatively easy to insertblindly a tube into the
esophagus.
That's where tubes go if youjust shove them into the mouth,
but their efficacy is at best.

(08:52):
Okay?
They did a perfectly reasonablejob for quite a while until
along came a second devicecalled a laryngeal mask airway.
Take a look in the show notesfor pictures of both of these
devices, both the king tube andthe LMA.
But the way that I think of anLMA is it's going to take the

(09:12):
shape of that CPR mask.
That bag valve mask, the partthat actually interfaces with
the face, which I think of asbeing the shape of a cupped
palm.
And it shrinks it down enoughthat we can slide it past the
tongue and let that cupped palmsit directly over the laryngeal
opening.
And there's a few differentversions of this.
Some of them are inflatable sothat you can put a deflated one

(09:35):
down into the, posteriororopharynx, and then you inflate
it to put pressure up againstthat opening and create a seal.
Others are very cleverlydesigned like the igel, such
that the shape simply sits verynicely over the laryngeal
opening.
These.
By kind of creating a seal overthe airway opening, perform the

(09:58):
same function of excluding anycontents which happen to rise
from the esophagus as vomitus.
And they also help seal againstthe outside world so that any
ventilations we provide aregoing in and out of the lungs.
The LMA is a little bit of anewer device.
The king or combi tube is alittle bit older.
So now let's jump into Tom'squestion.

(10:20):
So Tom works as a volunteer on arescue group, and he said that
until recently our guidelinesstated that a king LT tube
should be our preferred airwayadjunct for CPR, and that after
some initial bag valve maskventilation, we should switch to
that king LT tube as fast aspossible.

(10:42):
But there were some concernsthat King LT tubes can be
misplaced, particularly by lessexperienced volunteers.
And the newer guidelines suggestthat an IGEL laryngeal mask
airway should be the preferreddevice.
The notion there.
According to Tom was that theIGEL should be better for less
experienced medics, but that'sstruck him as odd because the

(11:04):
mechanics of inserting a king LTtube seem pretty foolproof.
And with the IGEL, he questionedwhether there could potentially
be improper sealing around thelarynx.
And these are, you know,providers who are at the
equivalent level of an EMTbasic.
So his question was whetherthere's any evidence out there
that would support the use ofeither an LMA type device or a

(11:28):
king LT for use in pre-hospitalcardiac arrest situations.
The first study that I want totalk about is called a
retrospective comparison of theKing laryngeal tube and IGEL
Supraglottic Airway Devices, astudy for the CARES Surveillance
Group, and this is by Smita Etalin Resuscitation 2023.

(11:52):
This was a retrospective studythat analyzed data from the
cardiac arrest registry toenhance survival, the CARES
Registry, and it comparedoutcomes in out of hospital
cardiac arrest between patientsmanaged with either the king
laryngeal tube or the IGELsupraglottic airway device.
It included only nontraumaticout of hospital cardiac arrest

(12:14):
cases with attempted EMSresuscitation, and this spanned
2013 to 2021, which is roughlywhen the LMA kind of came into
being.
I would say probably in 2013,king tube and combi tube devices
were more common.
And by 2021, a lot of hospitaluse had switched over to the LMA
type device.

(12:36):
Now they used a multi-variablelogistic regression in this
registry to attempt to accountfor other variables such as age,
sex, initial EK, G rhythm,whether or not cardiac arrest
was witnessed, et cetera, to tryto reduce the comparison to just
the airway device used.
Now, the primary outcome thatthey measured was survival with

(12:59):
a favorable neurological status.
So.
You know, awake able to performactivities of daily living, et
cetera.
And their secondary outcomeincluded survival to hospital
admission and survival tohospital discharge.
So what did they find?
The results showed that use ofthe I-G-E-L-L-M-A was associated
with a 45% increase in the oddsof a favorable neurological

(13:23):
survival.
So their odds ratio was 1.49,um, with a confidence interval,
not spanning one for the statsnerds out there.
Uh, a solid effect.
Additionally, IGEL use waslinked to a 7% increase in
survival to hospital admissionwith an odds ratio of 1.07 and a
35% increase in survival tohospital discharge.

(13:46):
So these findings suggest thatthe IGEL may be more effective
than the king LT in helping toimprove survival and
neurological outcomes in out ofhospital cardiac arrest
patients.
The second study that I'd liketo bring your attention to is a
similar study using a differentregistry called a retrospective
nationwide comparison of theIGEL and king laryngeal tube

(14:07):
Supraglottic airways for out ofhospital cardiac arrest
resuscitation, and this is inpre-hospital emergency care,
January of 2023.
In this study, it was aretrospective study using a.
Different registry from the ESOData collaborative over the
years 2018 to 2021, comparingoutcomes of, out of hospital

(14:28):
cardiac arrest in patientsmanaged with the IGEL or the KL
NAL tube.
Again, it was isolated only tonon-traumatic out of hospital
cardiac arrest cases where EMSattempted to resuscitate the
patient and they put in adevice.
Their primary outcome wassurvival to discharge home and
secondary outcomes include firstpass airway success.

(14:49):
So did they succeed in puttingit in the first time return of
spontaneous circulation?
Did they get a pulse back anddid the patient re-arrest in the
pre-hospital environment if theydid get a pulse back?
So they use the same kind ofmixed effects logistic
regression to try to isolate thecomparison to just the airway
device used kind of.

(15:10):
Using statistical wizardry totake age, um, you know, medical
comorbidities, other, other suchthings out of, out of there.
So this looked at 9,456 patientsof whom 59.8% were treated with
the IGEL, the remainder with theking tube.

(15:31):
What did they find?
Use of the IGEL in this registryas well was associated with a
greater survival to dischargehome with an odds ratio of 1.36
and higher first-pass airwaysuccess and odds ratio of 1.94
and increased return ofspontaneous circulation of 1.19
compared to the king lt.

(15:53):
It was also linked to lower oddsof pre-hospital re-arrest at an
odds ratio of 0.73 in thisregistry.
However, when it was used as theprimary airway management
device, they did find that theIGEL was not associated with
significantly greater survivalto discharge home.

(16:13):
They showed an odds ratio thereof 1.26 with confidence
intervals from 0.95 to 1.68.
So there is actually a signalthat probably it may help with
survival to discharge home, butit didn't reach significance in
this still relatively largesample.
So there's some discord therebetween the study and the prior.

(16:34):
However, survival,neurologically intact survival,
these kinda match between thetwo studies.
So between the two, the findingssuggests that overall the IGEL
may be more effective than theking LT in improving some
outcomes in out of hospitalcardiac arrest patients.

(16:54):
Now, both of these studiessuffer from the same
shortcoming, which is that it isa retrospective study.
So we don't know a lot aboutwhy.
For example, an IGEL or a KingTube might have been used.
My guess is that it'spredominantly based on the
transporting agency, but it'spossible that we are blind to

(17:15):
some patient characteristicsthat made.
You know, the EMTs put IGEL LSin people who they thought were
gonna do better, and kings inpeople they thought were gonna
do worse.
And that the differences thatwe've seen between these two
groups are due to unaccountedfor variables.
And that's the problem withretrospective studies in
general.

(17:35):
So what about prospective data?
Well, the last study that I'mgonna draw your attention to is
called.
A prospective observationalstudy comparing two supraglottic
airway devices in out ofhospital cardiac arrest.
And this is an open accessarticle.
Um, by, I apologize, I'm gonnabutcher this.

(17:56):
Lone Vic etal.
And this is in BMC EmergencyMedicine from 2021.
So in this study, this was aprospective forward-looking
observational study of the IGELversus the king LTSD device, a
slightly different king tube.
And it compared two EMS servicesthat were protocol to use the

(18:18):
IGEL to one that was protocol tousing the king tube.
They included 250 patients.
Who had an out of hospitalcardiac arrest, and they aim to
evaluate the difficulty ofinsertion, the number of
attempts required for successfulplacement and the overall
success rates of the devices.
The findings of this studyindicated that both devices had

(18:40):
pretty high success rates with.
First attempt insertion of theIGEL in 92% versus the UM, king
device in 89%.
The medium time to insertion wassimilar for both devices, but
overall fewer attempts wererequired for the IGEL.

(19:01):
Um, then for the King AirwaySupreme.
So this suggests this, uh,possibly a slight benefit to
using the IGEL over this Kingdevice.
However, with no significantdifference in complications
between the two and relativelysimilar rates, it seems like I.
At least prospectively, at leastthey are similarly easy to use.

(19:23):
The main limitation of thisstudy is that they didn't look
at very many patient-centeredoutcomes, and there's not really
any record of the training orexperience of the services using
these or other devices prior tothe study.
So if one of these was new tothem, it could have been more
challenging to insert.
So those are the three mainstudies that I was able to dig

(19:44):
up giving us insight intoI-G-E-L-L-M-A versus King.
Here's my take on it.
The data isn't perfect.
I'm surprised that there isn't aprospective head-to-head
randomized controlled trial thatI could find, but we've got what
we've got.
It looks like in retrospectiveout of hospital cardiac arrest

(20:06):
registries, the IGEL seems tobeat the king by a fair margin
to produce neurologically intactsurvival.
So I think we can safelyinterpret that to mean that it's
a generally superior device forproviding oxygenation and
ventilation during out ofhospital cardiac arrest.
Now, as I mentioned before, it'spossible that the results are

(20:26):
confounded.
Meaning that there are variablesthat we can't account for and
maybe higher performing groupsare using the IGEL, while
volunteers are all using KingAirways, and that could entirely
account for the observeddifference.
But the third study that wediscussed in Norway with, you
know, different EMS groupssuggest that probably that

(20:47):
difference doesn't account forall the effect.
I think that generally peoplewho think that the King Airway
device is superior.
To the IGEL have a preferencefor the King airway device due
to familiarity, these werestandard issue to a large number
of EMS services for quite a longtime.
There is a study out there ofnovice users using both the king

(21:09):
and the IGEL in a simulatedtactical environment, which we
didn't discuss here.
And novices generally prefer theIGEL airways and found them
easier to use.
So if you like the king airwayand you think it's easier to
use, you probably like itbecause you're familiar with it.
My experience in the emergencydepartment receiving patients
from the field with SupraglotticAirways in place is that,

(21:32):
generally speaking, the IGELdoesn't lie.
If you put in an IGEL airway, ifit looks like it's in, it's in
and the air is probably goingwhere you want it to go.
On the other hand, the king canlie because it can ride a little
high, it can ride a little low,and if one of those two balloons

(21:52):
happens to be sitting over thelarynx, then the air is not
going where you want it to go.
So the simplicity of the IGEL Ifavor, if you've slide it in
past the tongue, if you can'tpush it further, it's
essentially in place.
If you encounter a problem ofair leak, meaning you're trying
to put in air and you hear itcoming out from around the

(22:14):
device, you try to push it in alittle further and seat it
nicely, and if that doesn't doit right, then you're probably
off by a size.
You either need to upsize or youneed to downsize.
And anyone who is familiar withthe use of the IGEL knows that
probably 95% of adult patientscan be successfully treated

(22:34):
using a size for I-G-E-L-L-M-A,which is the green one.
But in some big people, we gottago up to the orange one, or you
might have to go down a size ifthey're smaller.
So it's not a panacea to usesize four, but it works a heck
of a lot of the time.
And it's not as germane to thisdiscussion of pre-hospital
treatment, but also when thepatients get to the hospital,

(22:57):
it's a lot easier to manage themwith that IGEL in place.
Why?
The answer is I can secure theirairway through the IGEL using a
fiber optic scope.
It's built for that.
We can keep breathing for them.
While I do that, I can put ascope through it and slide an
endotracheal tube in there.
No problem.
If there's a king tube in there,unfortunately I have to pull it

(23:20):
out before we start to intubate.
In most cases, it's not anissue, but in some tenuous
airways, it's pretty nice to beable to ventilate while securing
the airway or be able to fallback on the IGEL if need be.
Definitely the most commonissues with the IGEL is running
in, or any laryngeal airway forthat matter, is an air leak.

(23:42):
And as I discussed, the easiestway to treat this is usually
just to advance it slightly andmake sure it stays secured, and
then if not to change the size.
The other pro tip that I havefor you for the pre-hospital
environment is that.
Using an extension set,basically a little crinkle tube
that allows you to attach yourBVM to the LMA with a bend or a

(24:05):
little bit of extension.
Really helps when transportingin the pre-hospital environment
because you have to occasionallyput the bag down, lift the
patient, move the patient.
And when you do that, a littleextension set keeps that bag
from pulling on the airway andpotentially displacing it.
So if you're buying the IGEL foryour agency, there are two
packaging types and one of themcomes with that flexible linking

(24:28):
hose and a securing tie.
And the cheaper one comes withjust the IGEL alone.
I like the first one.
I like the full package becauseit really reduces jostling the
airway and makes it easier tobag the patient when in a
chaotic environment.
So that's it.
That's what I've got on Kingversus IGEL.
My personal bias is that Itrained with the IGEL and my

(24:51):
contact with the King Tube hasbeen through more rural EMS
agencies that are still usingthese until they probably expire
and then have an opportunity topurchase new airway equipment.
But if you haven't had thechance to use an I-G-E-L-L-M-A,
you should train on it.
You can reuse one of themindefinitely for training, and
they're super easy to use.

(25:13):
I carry one in my ski patrolvest.
I carry a size four LMA becausein some situations you really
can't beat it.
Thanks again for listening toWilderness Medicine updates.
I hope that this has been usefulto you.
As always, I encourage you towrite in with questions.
I really appreciate hearing fromlisteners from around the globe

(25:36):
Recently, there's been a lot ofoutreach from both Germany and
South Africa, which is awesome,but I know that there's a bunch
of you out there in othercountries as well, and the uk,
Europe, Australia, New Zealand,the United States and Canada.
So if I haven't heard from you,I'd love to.
If this raises any questions oryou have any issues that you're

(25:57):
running into with your team,please send those questions my
way because if you havequestions, someone else does and
we can really try to get ananswer dialed.
Until then, if you find thispodcast useful, as I've
mentioned before, there's twoways that you can support me.
The first is on whateverplatform you're using, whether
it's iTunes, Spotify, orsomething else.

(26:18):
Give me that five star ratingthat helps us get exposure to
more people out there.
Get suggested by the algorithm.
And then the other thing you cando for me, which is super
helpful, is if you have anotherEMT doctor, nurse SAR member,
your ski partner, who you thinkwould benefit or enjoy listening

(26:38):
to one of these episodes.
Please share it with them,expand the audience.
I really love, um, hearingfeedback from everyone and each
time I'm putting out a podcast,it's growing.
The number of you who arelistening to the whole thing and
responding with questions isincreasing.
It feels like there's somemomentum out there.
And now that we've hit episode20, we have crossed into the top

(27:01):
1% of all podcasts of all time.
So thanks for sticking with me.
I appreciate your attention.
I'm here to serve you and untilnext time, stay fit, stay
focused, and have fun.