November 14, 2024 • 42 mins
In episode 17 of Wilderness Medicine Updates, host Patrick Fink delves into the ICAR resuscitation algorithm for buried avalanche victims. The episode reviews the physiology of avalanche burial and discusses critical determinants of survival, such as duration of burial, airway patency, signs of life, and lethal injuries. The Basic Life Support (BLS) and Advanced Life Support (ALS) algorithms are explained in detail, with a focus on the practical application for both amateur and professional rescuers.
The episode also includes two detailed case studies that illustrate the application of the resuscitation algorithm, providing listeners with practical scenarios to better understand the protocols. Key insights on the importance of quick action, hypothermia, and ongoing CPR are highlighted, making this episode essential listening for anyone involved in avalanche rescue operations.
Ep. 12 - Resuscitation of the Buried Avalanche Victim, Part 1: Physiology
ICAR Rescue Algorithm
ICAR Paper in Resuscitation
Chapters:
00:00 Ep. 17 - Resuscitation of the Buried Avalanche Victim, Part 2
01:26 Review
08:52 BLS Algorithm
14:30 ALS Algorithm
25:30 Interlude
25:30 Case 1: Partner Rescue
31:01 Case 2: Professional Rescue
39:54 Conclusion/Outro
As always, thanks for listening to Wilderness Medicine Updates, hosted by Patrick Fink MD FAWM.
Connect with us by email at wildernessmedicineupdates@gmail.com.
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Patrick (00:08):
Hello and welcome back to wilderness medicine updates.
I'm your host Patrick Fink.Thisweek, episode 17 resuscitation
of the buried avalanche victim.
Part two, we're going to diveinto the rescue algorithm.
If you haven't listened toepisode 12, I strongly suggest
that you go back and do that.
(00:28):
In that episode, I talk aboutthe physiology that underlies
the resuscitation algorithm.
It explains why we try toresuscitate certain patients and
why we will quit and call it onothers.
So go ahead and take a listen tothat.
In today's episode, I'm going tostart by giving just a quick
review of a couple points.
(00:50):
then we're going to dive intothe resuscitation algorithm.
You can find that ICARinternational committee on
Alpine rescue.
Algorithm in your show notesthere.
If you have the opportunity tolook at it, it might help you
kind of work your way throughthe first half of this show, but
if you don't have it, noproblem.
I think you'll still get a lotout of listening to it.
(01:12):
And so after we go through thatalgorithm, we're going to take a
brief pause, and then we'regoing to jump into a couple
cases that help us illustratehow we might apply this
algorithm to the criticallyburied avalanche victim.
Imogen (01:26):
Review of Avalanche Burial Physiology
Patrick (01:28):
let's start by reviewing how people die in
avalanches.
And in this episode, we're goingto be talking about the
critically buried avalanchevictim.
What does that mean?
We're talking about someone whois buried with their head, their
airway, completely under thesurface of the snow.
And as soon as that happens, theclock is ticking.
If you look at a graph or asurvival curve of buried
(01:53):
avalanche victims, what we seeis that in the first 10 minutes,
about 10 to 20 percent of peopledie.
And the reason for that is thatthey can die of trauma.
They're very unlikely to die ofother causes during that period
of time.
They just haven't been under thesnow for long enough.
So if they're dug out in thefirst 10 minutes and they're
(02:13):
dead, they have no pulse, theyhave no respirations.
They probably died of trauma.
As soon as we get beyond that 10minute mark and extending out to
maybe around 60 minutes, we'renow talking about asphyxia as
the primary cause of death.
So at that 10 minute mark, about80 percent of our buried
avalanche victims are alive.
(02:33):
But as we get out to around 60minutes, the survival curve
drops pretty radically.
It drops well below 20 percentat around 30 minutes, and levels
out at about 10 percent at 60minutes.
So, 80 percent down to the 10%,that's 70 percent of our buried
(02:54):
avalanche victims are going tobe dying of asphyxia.
And that means that theysuccumbed to a lack of oxygen,
or in some rare cases, a veryhigh carbon dioxide level.
Now, who survives beyond 60minutes?
The people who survive beyond 60minutes are the ones who
probably had a very big airpocket.
(03:15):
They had plenty of room toexchange gas with their
environment, and they didn't dieof trauma.
So if we encounter a buriedavalanche victim, who's been
under the snow for more than 60minutes.
We need to think about thepossibility that they could have
died of hypothermia.
We consider hypothermia after 60 minutes.
(03:36):
But, in truth, most peoplearen't going to die of
hypothermia in an avalanchebecause you're just not buried
for long enough, even if it's acouple of hours.
Studies have looked at howquickly people's temperatures
decline under the snow, and it'smaybe 1 to 2 degrees centigrade
every hour.
That's really slow, particularlyif we're talking about critical
(03:57):
hypothermia with a temperatureof less than 30, getting there
from a normal body temperatureof around 36, we're talking
about maybe 3 hours.
Now, there are some, uniquecases if you're in a creek, if
you're really wet, you mightincrease conductivity and
cooling.
So, we do allow for thepossibility that a buried
avalanche victim may behypothermic.
(04:19):
And those people can survive asurprisingly long period of
time.
Now that we've reviewed howpeople die in avalanches, let's
talk about critical determinantsof survival.
So, these are the things that wewant to assess.
In the back of our mind, we'reactively recording when we're
rescuing an avalanche victim.
(04:41):
The first critical determinantof survival is the duration of
the avalanche burial.
Namely, at what time did theavalanche occur?
And at what time did thepatient's head and airway get
accessed and pulled out of thesnow?
The reason that this isimportant is because that is
going to help us determine, dowe think this patient likely
(05:02):
died of asphyxia?
Or do we need to be consideringhypothermia as well?
If we're digging the patient outin under 60 minutes, the
likelihood that hypothermia isthe cause of their cardiac
arrest is very low.
So when we're rescuing apatient, we want to know what
time the avalanche occurred, andwe want to take note when we
finally get to the head.
(05:24):
Then, when we get to the head,there's the second critical
determinant of survival, whichis the patency of the airway.
I'm not talking about thepresence of an air pocket around
the patient's head, and that'soften hard to evaluate when,
you're going after him with ashovel, and maybe someone
stepped near the head, But whenyou access the patient's face,
are both the nose and mouthcompletely occluded with snow?
(05:47):
Are they blocked?
Are they packed?
And the reason for that, go backto episode 15 and look at the
research around airway patencyin avalanche victims.
The survival of a buriedavalanche victim is very low
beyond 15 minutes in peoplewhose mouths and noses are
packed with snow.
And that's because if you haveno chance of exchanging gas with
(06:09):
your surroundings, you're goingto die of asphyxia in like eight
minutes, no hope.
So that's something else we wantto take note of as we're
resuscitating our patient.
Another no brainer, criticaldeterminants of survival, that
does factor into our algorithm,is does the patient have signs
of life?
When we pull them out of thehole, do they exhibit signs of
life?
(06:29):
And what do we consider signs oflife?
So, obviously, if they're alert,they're alive.
But if they have any kind ofverbal or, motor response to
pain, they're alive.
Any movement at all.
Any breathing.
A palpable pulse.
We consider those signs of lifeand those patients who have
(06:51):
signs of life are treateddifferently in our resuscitation
algorithm.
Finally, when we access thatpatient, there's the fourth
critical determinant ofsurvival, which is, does the
patient have a clearly lethalinjury?
These are the patients whoclearly died of trauma, and we
are not going to subject ourteam to the trauma and the
(07:12):
difficulty of resuscitating thatpatient or trying to, if they
have a clearly lethal injury,what is a clearly lethal injury?
The two which we include hereare decapitation, the head is
not connected to the body, ortruncal transection, they've
been cut in half.
The algorithm also includesevidence of decomposition, but
(07:35):
clearly this applies just toprofessional teams who are
perhaps retrieving a body afterseveral days.
So not so relevant to theaverage rescuer.
So to recap, in the first 10minutes, people die of trauma.
In the next 50, out to about 60minutes.
(07:58):
We generally assume that theydied of a lack of air or
asphyxia.
And then if they've been buriedlonger than 60 minutes and they
have a patent airway in an airpocket, perhaps we start
thinking, Oh, maybe hypothermiais a factor.
And when we access that patient,when we actually reach their
face, we're going to take noteof the time and how long it has
been since the avalancheoccurred.
That's our duration of burial.
(08:18):
We're going to check their noseand mouth.
That's our airway patency.
Is it blocked with snow or is itopen?
And then we're going to evaluatethat patient for signs of life.
Are they alert?
Are they speaking?
Do they exhibit any motorresponse to pain or verbal
prompting?
Are they breathing?
And do they have a pulse?
And we're going to do a reallyquick evaluation to say, Hey, do
(08:42):
they have a clearly lethalinjury?
And then we're going to applythe algorithm.
Imogen (08:51):
The Basic Life Support Algorithm
Patrick (08:53):
This international committee on Alpine rescue
algorithm, the ICAR Algorithmfor the resuscitation of the
critically buried avalanchevictim begins with basic life
support care.
It doesn't matter if you're anALS provider or a BLS provider,
you're going to be providing BLScare when you first access the
patient.
(09:13):
If you're looking at thealgorithm, you're going to see
that there are places to recordcertain critical pieces of
information.
We really want to know the timeof the avalanche.
When we expose the patient'shead and was the airway
obstructed.
And from that, we can derive theduration of burial.
So as the BLS provider reachingthe patient, you're going to
perform your initial assessment.
(09:34):
You're going to access theairway and you're going to
assess for signs of life.
If the patient is moving,they're alive.
If they are breathingspontaneously.
Then we can treat them accordingto normal trauma and hypothermia
care.
We're going to handle themgently.
We're going to take precautionsagainst spinal trauma.
We're going to treat hypothermiaas appropriate.
(09:55):
We're going to transport thatpatient to a hospital for
further evaluation.
But if this patient is notexhibiting signs of life.
Then we're going to startproceeding down our BLS pathway.
And the first decision point onthis BLS pathway is how long was
the patient buried?
We divide this into a burialduration of less than 60 minutes
(10:18):
and a burial duration of longerthan 60 minutes.
The reason for that to reiterateis that if someone is buried
less than 60 minutes, we assumethat their cause of death.
The cause of death that we couldpotentially reverse would be
asphyxia.
However, if it's greater than 60minutes, then we're thinking,
Hey, maybe hypothermia is atplay.
So let's talk about less than 60minutes.
(10:40):
First, if someone has beenburied for less than 60 minutes,
we are presuming asphyxia as thecause of cardiac arrest.
And we're going to check forsigns of life for no more than
10 seconds because the clock isticking.
They are perhaps asphyxiating.
We do not want to wait too long.
If there are no signs of lifeand we have checked for 10
seconds, then we're going tobegin with giving 5 rescue
(11:01):
breaths.
The reason we go to the rescuebreath first is that we're
treating asphyxia, so deliveringbreaths is our priority.
Then, without hesitation, we'regoing to begin CPR.
Now, for a burial duration ofgreater than 60 minutes, Our
presumed cause of death ispotentially hypothermia.
In this case, we're going tocheck for signs of life for up
(11:23):
to one minute.
Why is that one minute insteadof 10 seconds?
The reason for that is thatsomeone who is profoundly
hypothermic can have profoundlyslow vital signs, perhaps one a
minute or a heart rate of six.
(11:45):
If they have any signs of life,then we are going to treat them
just like the other patient.
We're going to treat them withappropriate trauma and
hypothermia care.
We're going to handle themgently because hypothermia can
make people very fragile.
Their hearts get very grumpy.
We're going to take precautionsagainst trauma.
(12:06):
And we're going to transportthem to hospital.
But, if there are no signs oflife in this patient who's been
buried for greater than 60minutes with presumed possible
hypothermia, The next questionthat we have is, is EKG
monitoring possible?
If so, slap that on.
But start CPR now.
(12:26):
There is only one caveat to bothof these pathways, which is we
are not going to start CPR ifthe burial duration has been
greater than 60 minutes, andthey have an obstructed airway,
and that EKG monitor that wejust got shows asystole.
The reason for that is thatthey've been buried a long time,
(12:48):
their airway is blocked, theyalmost certainly succumbed of
hypoxia, and they are showingthe heart rhythm consistent with
that, which is no heart rhythm.
Any other heart rhythm likeventricular fibrillation or
pulseless electrical activity,PEA, an unknown heart rhythm we
don't have monitoring available,we're still going to continue to
(13:09):
resuscitate that patient.
Burial duration, over 60minutes.
Airway blocked with snow,asystole on the monitor, we're
calling it.
That concludes the BLSalgorithm.
To reiterate, we want to performour initial assessment, and then
we're going to divide thepatients based on whether they
were buried for less than orgreater than 60 minutes.
(13:31):
If they were buried for lessthan 60 minutes, we presume that
they were asphyxiated, we checkfor signs of life for 10
seconds, and then we begin CPR.
If they were buried for greaterthan 60 minutes, we think
hypothermia is possible, and wecheck for signs of life for up
to a minute.
If they're not present, then wereally want that EKG monitor,
but we're going to begin CPRalso in this setting.
(13:54):
If you're a BLS provider, we'renot going to call it.
We're not going to quit on thispatient.
Once CPR has started, they needto be.
transported to either an ALSprovider or they need to go to
hospital.
And the reason for that is thatthere are a small subset of
these patients who couldpotentially survive.
And so we don't have the toolsto call it in the field as a BLS
(14:15):
provider alone, unless there'sthat burial duration over 60
minutes, plugged airwayasystole.
Now, if you have ALS resources,we algorithm to the ALS care.
Imogen (14:30):
The advanced life support algorithm
Patrick (14:32):
Our ALS algorithm begins.
with the same BLS care.
It's the exact same algorithmuntil we reach the point at
which we just concluded, wherewe have started CPR.
We want to know burial duration,airway patency, we're checking
for signs of life, we'restarting CPR.
But then as that ALS provider,we're hopefully arriving with a
(14:53):
few extra tools.
And those tools are the abilityto monitor the patient's heart
rhythm, and ideally the abilityto measure the patient's
esophageal temperature.
We want to know a core bodytemperature.
So, as that ALS providerarriving on scene, CPR is going
to continue while we make someadditional determinations.
(15:13):
We want to measure theesophageal temperature as soon
as possible, and we want to findout the heart rhythm.
We can now move to page two ofthis two page algorithm if
you're playing along at home.
The simpler side of thisalgorithm is for patients who
are buried less than 60 minutesbecause they are the ones who
have presumed asphyxia.
There are fewer things that wemight do for this patient and
(15:36):
fewer reasons why we might tryto resuscitate for longer.
So, let's start with the burialduration of less than 60
minutes.
As that ALS provider, you thenmeasure an esophageal
temperature if you can.
If the patient's temperature isgreater than 30 degrees Celsius,
if they do not have criticalhypothermia, or if we can't
(15:56):
measure their temperature, thispatient who has been buried for
less than 60 minutes shouldprobably receive about 20
minutes of CPR.
And if that is not successful,we'll consider terminating CPR,
because that patient likelysuccumbed due to hypoxia and
with a warm enough core bodytemperature, we're not risking
missed hypothermic arrest.
(16:19):
Note that in this case, if thetemperature is unknown, the
algorithm also recommends thatwe don't necessarily perform
prolonged CPR, and that'sbecause the likelihood that this
patient is hypothermic afterthis short period of time And is
deserving of prolongedresuscitation is really low.
They say consider becausethere's always going to be some
kind of extenuatingcircumstance, but we'll consider
(16:41):
terminating.
How about if you get thattemperature and it's less than
30 degrees Celsius.
So they've been buried less than60 minutes, but they're cold,
cold, cold, cold.
They have severe hypothermia.
Maybe they were hypothermicbefore they got buried.
If that's the case, then CPRshould continue until they can
(17:01):
go to hospital.
If you have a choice ofhospitals, you should transport
them to a hospital with ECLS,which is called extracorporeal
life support.
That's a heart lung machine orECMO.
That's how we warm up theseverely hypothermic patient.
So if the patient is reallycold, CPR should continue.
(17:22):
A good rule of thumb here isthat someone is not dead until
they are warm and dead.
That's it, pretty simple, so forthe ALS provider, that less than
60 minute burial, if they'recold, they go to hospital with
continuing CPR, if they're not,we're going to work for 20
minutes or so and then considerterminating.
(17:44):
Let's turn our attention to theslightly more complicated burial
duration of more than 60minutes.
For the patient who's beenburied more than 60 minutes,
hypothermia is now apossibility.
Because of that, we really wantto see the EKG tracing.
This is someone that we justpulled out of the snow, who has
been buried for more than 60minutes, and they're not showing
(18:05):
signs of life, but theprofoundly hypothermic patient
can be sort of like Han Solo ina block of carbonite.
It could be kind of a suspendedanimation situation.
So we really want to see thatEKG tracing, And the rhythm is
pulseless electrical activity,some kind of organized rhythm on
the monitor, but no pulse.
Or we see ventricularfibrillation.
(18:28):
Or we can't determine what therhythm is.
Basically anything but asystole.
Then we move to our sametemperature dichotomization.
And the reason for that is thatthese abnormal heart rhythms in
the presence of a very coldtemperature is consistent with
severe hypothermia.
They can also be signs andsymptoms of asphyxia.
(18:50):
So again, if the patient is verycold, they're going to be
transported to hospital, theyhave any kind of rhythm on the
monitor, they're very cold.
They're going to the hospitalwith ongoing CPR in this group.
However, the patients who havebeen buried for longer than 60
minutes, if we don't know thetemperature.
(19:10):
And they have any heart rhythmbut asystole, they also should
go to the hospital.
Because we think that, okay,that's a subset of people who
might be hypothermic, we justcan't tell.
They deserve a chance.
They should go to hospital withongoing CPR.
But if they've got ventricularfibrillation, PEA, anything but
asystole, or we don't know theirrhythm, and their temperature is
greater than 30 degrees Celsius,we're gonna quit after 20
(19:33):
minutes, just like before.
We would consider termination ifwe don't get return of
spontaneous circulation or ROSCafter 20 minutes.
That's because if they're notprofoundly hypothermic, that V
fib, that PEA is probably due toasphyxia, and we're not going to
resuscitate someone who has achance of walking out of the
hospital neurologically intact.
(19:57):
But let's say, okay, rewind.
This is a patient who's beenburied for 60 minutes.
We throw those pads on, we haveC through AED, or we have a 3
lead, and we're looking at theelectrical activity of the
heart, and there is none.
There is asystole.
Well, now the question is, wasthis a witnessed cardiac arrest?
(20:18):
Weird question, right?
For the critically buriedavalanche victim.
This applies to an interestingsubset of patients.
The answer to this is probablyno, no one saw them go into
arrest under the snow.
However, there may be a set ofpatients where we dig them out.
They have signs of life.
They've been under there a longtime and then they walk a little
bit.
They walk away from that holeand then they collapse into
(20:39):
cardiac arrest.
there's the possibility forwhat's called after drop, which
is where the blood in theextremities is super cold.
And so this patient who'sborderline profoundly
hypothermic, as soon as theystart getting up, moving around,
becomes profoundly hypothermicand goes into cardiac arrest.
So if it was a witnessed cardiacarrest, we're going to do the
same thing.
We're going to measure theesophageal temperature and if
(21:00):
they're cold or it's unknowntemperature, we're going to
transport them.
But if they're warm, we're goingto work them for 20 minutes and
then call it.
The more common situation isthis was not a witnessed cardiac
arrest.
They died at some pointunderneath the snow.
Then our question is, was thereairway obstructed?
(21:20):
We're taking note of that.
When we first reached thepatient, If the airway is
obstructed, an there is an EKGthat shows asystole in an
unwitnessed cardiac arrest insomeone who's been buried for
over 60 minutes, we're gonnacall it.
They've been buried a long time,they have no heart activity,
their airway's blocked, meaninga very high probability of
asphyxia.
(21:41):
There is no point in continuingthat resuscitation.
If their airway was open, Or wedon't know because no one
actually looked, because it wasa chaotic scene.
Then we're going to apply thetemperature algorithm again.
We're going to check for atemperature less than 30, or if
we don't know it, we're going todo CPR until we get him to the
hospital.
(22:01):
The reason that we're taking allthese people who have a
temperature less than 30 to thehospital is that they're
refrigerated.
Their metabolic state has beenreally low.
There is a chance of a goodneurological outcome.
If they can be warmed andprotected, some of them will
walk out neurologically intact,even if they've been buried for.
(22:21):
An hour, two hours.
If you're playing along at homewith the ALS algorithm in front
of you, you'll see that afterarrival to the hospital, there's
another square and that's tomeasure potassium and calculate
a hope score.
I'm going to just address thatsuper briefly because it is not
relevant to the field care ofmost avalanche victims.
(22:42):
Unless you live in a magicalworld where you have point of
care, potassium testing out inthe field, basically, if the
potassium level is super high,That suggests cellular death,
and those patients do not dowell even if we warm them up.
And then the HOPE score is ascore that helps determine
(23:03):
survival after extracorporeal rewarming, and it helps us decide
in hospital who deserves thoseadvanced interventions, which
can be very expensive, veryinvasive.
And, do pose some risk toproviders, like needle sticks,
procedures, that kind of thing.
And we don't want people to endup on a heart lung machine with
a dead brain because that justcreates distress for the family.
(23:25):
So we, we try to decide who isbest to resuscitate in hospital
using a point of care potassiumand the HOPE score.
But that's a subject for anotherday.
So going back to high level asan ALS provider, you're going to
do the same.
BLS stuff.
We're checking for signs oflife, taking note of how long
(23:47):
the patient's been buried, andwe're starting CPR.
But our goal is to get an ECGmonitor on there.
And if we can to check thepatient's temperature, then
we're dividing our care based onwhether it was a short burial or
a long burial.
If it was a short burial, great.
We are going to measure thatpatient's temperature and we're
going to bias towardsterminating.
Essentially, if we don't knowthe temperature, we're going to
(24:09):
terminate after 20 minutes, orif it's over 30 degrees, we're
going to terminate after 20minutes.
anyone whose core temperature isless than 30, they go to
hospital.
if it's a burial duration ofgreater than 60 minutes, or we
don't know how long the patientwas buried, then we're going to
start dividing based on EKG,witness cardiac arrest, and
(24:30):
airway patency.
People who have V fib or PEA oran unknown rhythm, we divide
based on temperature.
A witness cardiac arrest, wedivide based on temperature.
PEA and a patent airway, wedivide based on temperature.
And these people have beenburied a long time, but we don't
(24:53):
know their temperature.
We bias towards taking them tothe hospital.
We transport with CPR.
That's the main difference incomparison to the less than 60
minutes group.
And finally, if the EKG shows asystole, it was an unwitnessed
arrest.
The airway was obstructed withsnow.
We're going to terminate CPRbecause the likelihood of
survival is low.
(25:16):
All right.
We did it.
We got through the BLS and theALS algorithms.
Let's take a short musicalinterlude and then we'll dive
back in with a couple of casesto apply the algorithm.
Imogen (25:39):
on to the rescue scenarios
Patrick (25:40):
as we worked through the scenarios.
I want you to think about whatyou would do and how you would
approach.
This case that we're talkingabout.
When you hear this.
The sound.
Think about what.
You would want to know, or theactions that you would take
next?
Imogen (26:00):
Case 1
Patrick (26:03):
So you're out with a ski partner as a group of two.
There's been a persistent slabproblem, maybe 50 centimeters
deep.
In the snowpack.
But the difficulty of triggeringit has been increasing.
Over the last few weeks.
So for better for worse today,you've.
Been stepping out into biggerterrain.
Skiing and Alpine bowl andworking.
And your runs further into thebowl.
(26:24):
On the third run.
Your partner's keys first andtriggers a large slab avalanche.
You know, at the point lastseen, but you don't see your
partner and you can't.
I can't hear him when the debrissettles.
You note the time of the.
Avalanche conduct a beaconsearch.
Locate a signal with the lowestpoint at 1.2 meters.
(26:45):
Digging aggressively.
Only into the debris from about1.5 meters, downhill of your
probes.
Probe strike you, reach yourpartners face.
What do you want to know?
And what do you Want to do.
First.
Check the time note the durationof the burial.
And this case, let's say He'sbeen buried for 20 minutes.
(27:07):
As you reach his face, yourpartner doesn't have an air
pocket around it, but.
His mouth and nose.
Aren't blocked with snow.
They're open.
He doesn't.
Have any obviously fatal,traumatic injury.
And you get them out onto.
a small platform he's flat onhis back.
Let's.
Pause and think about where weare and the algorithm.
20 minute burial open airway.
(27:27):
We're proceeding down the lessthan 60 minutes, burial.
Pathway.
What do you assume?
Is the potential.
I will cause.
Of arrest.
And what are your next Fewactions.
The presumed cause of death.
If your partner looks dead, is.
(27:48):
Uh, we'll check for signs oflife for, at most.
10 seconds because he's beenburied for less than 60 minutes.
He has no.
Signs of life, no movement, nobreathing, no pulse.
We give five.
Rescue breaths and start CPR.
Now we're in a tough situation.
We're doing CPR solo.
Calling for help.
(28:09):
Isn't likely to do anything forour partner.
Because of the time needed.
For any.
Help to arrive.
How long should we keepresuscitating him?
In general.
And to be clear, this isoutside.
The guideline because it doesn'tdirectly address partner rescue.
(28:29):
I think.
That 20 to 30 minutes of CPR isthe most that should be
attempted.
There's a few reasons for this.
Uh, survival after.
For a longer period of CPR isvery unlikely.
Increasingly unlikely.
And CPR quality is likely todrop off.
Uh, pretty quickly with a singlerescuer.
It is hard work to do good CPR.
(28:51):
We tire out.
And the effort of.
Doing CPR for a longer can startto compromise the safety of the
rescuer.
Causing exhaustion, sweating,increasing risk of hypothermia,
et cetera.
So those are all reasons not tocontinue.
Longer than about 20 to 30minutes.
Of course, I'm never going totell you that you.
You shouldn't do it longer.
(29:12):
And you'd be hard pressed tostop on.
On a loved one.
But this is a happy podcast.
At.
Least for now.
So in this case, your partnerstarts trying to breathe.
And you check for a pulse and henow has a pulse, but he remains
unresponsive.
where do you go from there?
(29:34):
We're going beyond.
The algorithm now, but mypriorities would be these first
call for help.
There's no way I'm getting himout alone.
We need to be careful.
Careful with him and traumaremains a possibility.
So do a Thorough secondary examand make sure he's not bleeding.
I'd make sure that.
That is.
Breathing seems adequate, youknow, 10 to 12 breaths per
(29:54):
minute.
I'm not Going to have tosupplement his breathing.
Then I'm going to start.
Protecting him because we'regoing to be there for a while.
I want to get him off the snowonto something.
Insulating cover him withlayers.
Hopefully not, but maybe.
Think about what's going tohappen.
If I have to spend the night.
I'd better hope help.
Is coming.
I'm going to reevaluatefrequently and be.
(30:15):
We prepared.
Should he rearrest?
It's unlikely.
Unless it becomes hypothermic,but I don't know what I have
with me here.
So that concludes the first casepartner rescue.
Less than 60 minutes.
We assume that if our partner.
is not breathing and shows nosigns of life has no pulse.
But the cause of death that wecan potentially reverse as this
(30:37):
fixture.
And to review, we're going tocheck for.
Signs of life for no more than10 seconds.
We're going to get five rescuebreaths start.
Start CPR and continuing thatCPR for somewhere between 20 and
30 minutes.
And if we get return ofspontaneous circulation, hurrah,
Our lives.
Just got much more complicated.
We're going to need to thinkabout our next steps.
So that's.
Simple simple enough.
(30:59):
Let's move on to case two.
Imogen (31:01):
Case 2
You're working as a professionalski patroller at a large ski
resort in the Pacific Northwest.
It's early spring, the first bigwarm up of the year, and the sun
is shining.
The avalanche cycle that wasoccurring on the February rain
crest has been quiet for morethan a month, and you've been
getting bored of ski cuttingsmall windslabs.
(31:24):
However, around 2 p.
m., you receive a report of apossible avalanche in the upper
bowl of the resort.
The reporting party reports thata cornice fell, And caused an
avalanche above a traverse andthat multiple skiers and riders
were below the avalanche.
The radio dispatcher sends allavailable resources to the scene
and an organized rescue begins.
(31:45):
A hasty beacon search reveals nosignals, but a witness confirms
that the three victims wereburied.
A probe line begins searchingand you arrive at the scene as
the ALS lead.
You can see that the cornicefall triggered a deep wet slab
on the February raincrust and alarge pile of big blocky debris
is below.
Use stage to respond to victimsas they're located.
(32:08):
Critically Buried Victim 1.
Patrick (32:12):
The first probe strike happens about 20 minutes after
the avalanche, and the patientis excavated and exposed at 26
minutes.
You arrive to the scene with CPRongoing.
What do you want to know?
This is an approximately 22 yearold male snowboarder.
Burial time was 26 minutes, andhis airway was not blocked with
(32:34):
snow.
You slide in an esophagealtemperature probe, and his body
temperature is 35 degreesCelsius.
CPR is ongoing.
What next?
CPR should continue for at least20 minutes.
After 10 minutes of CPR, ROSC isobtained.
(32:55):
Success! You assist in post ROSCcare, including trauma
evaluation and packaging.
But you must now turn yourattention away, because you're
called to.
Imogen (33:04):
Critically Buried Victim 2.
Patrick (33:07):
The second victim is excavated after 65 minutes.
You arrive on the scene, and CPRhas already been started.
What do you want to know?
This is a 45 year old femaleskier.
Burial time was 65 minutes, andher airway was occluded with
snow.
What next?
(33:32):
You instruct your patrolcolleagues to continue CPR.
You place three lead electrodes,and during the next CPR pause,
you note that the patient is inasystole.
CPR resumes.
So, to summarize, this patienthas been buried for more than 65
minutes.
has no palpable pulse, hasongoing CPR, and the underlying
(33:52):
rhythm is asystole.
What do you do?
Unfortunately, this 65 minuteburial with asystole, in a woman
who had an occluded airway, hasno hope of survival.
You instruct your colleagues tocease CPR, and you explain your
reasoning.
(34:13):
But there's no time yet todebrief, Because the probe line
has uncovered.
Imogen (34:17):
Critically Buried Victim 3.
You already know the informationyou want to know right away, so
I'll give it to you.
This is a 36 year old male skierwearing wet jeans and a cotton
hoodie.
He has been buried for 90minutes.
The team noticed a large airpocket when he was excavated,
and his airway was open.
(34:38):
He is unresponsive, has nopulse, and CPR is ongoing.
What are your next actions?
Now, you're no seasoned pro atthis, but you do have a little
laminated copy of the algorithm.
So, like a boss.
You hook him up to a 3 lead, andwhile waiting for a CPR pause,
(34:59):
you slide in an esophagealtemperature probe.
At the next pulse check, heremains pulseless.
He's in ventricularfibrillation.
His core temperature is 29degrees Celsius.
What are your next actions?
And are there any changes thatyou need to make to your
standard cardiac arrest care forthis hypothermic patient?
(35:22):
You defibrillate him and havethe team resume CPR.
You inform dispatch that youneed an air rotor resource to
transport this patient to anECLS capable hospital with CPR
ongoing.
For You have a somewhatprolonged toboggan transport
ahead of you.
He remains in V fib.
He remains in ventricularfibrillation.
(35:46):
This gives us a chance to talkabout a few extra credit points
for the care of these severelyhypothermic avalanche victims.
We're gonna briefly coverdefibrillation, epinephrine, and
what's called intermittent CPR.
Ventricular fibrillation in theprofoundly hypothermic patient
is due to cardiac irritabilityfrom the very low temperature.
Those heart cells just don'tlike that low, low, low
(36:08):
temperature.
So defibrillation may beunsuccessful until the patient
is warmed, and excessiveattempts at defibrillation can
be harmful to that heart muscle.
So for patients with a coretemperature of less than 30
degrees Celsius, we will limitthe number of defibrillation
attempts to three tries untilthe patient is warmed.
So if that patient remains inventricular fibrillation after
(36:30):
three attempts, We're not goingto shock further, we're just
going to continue CPR until wecan warm up the patient.
For the same reason, instead ofgiving multiple rounds of
epinephrine like you might in anormal cardiac arrest, We should
withhold epinephrine until thatcore temperature is greater than
30 degrees Celsius.
This is because the epinephrinecan increase the cardiac
irritability and make it harderto terminate the ventricular
(36:52):
fibrillation, which is itselfprimarily due to the very low
temperature.
So this patient that we'retransporting in V fib, we might
shock them up to three times,but we're not going to give them
any drugs.
Now I mentioned that we have aprolonged transport and this
patient has CPR ongoing, so whatare our options there?
The first and riskiest option isto try to put a patroller in the
(37:14):
toboggan performingcompressions.
That doesn't work well.
CPR quality is likely to be low,and there's significant risk to
the patroller performing thecompressions while you move, and
changing patrollers in and outis tough.
my hope is that in thissituation you might have access
to mechanical CPR.
I'm talking about a Lucas typedevice.
(37:35):
That device would allowcompressions to continue in an
ongoing manner while the patientis transported.
You're only going to be able toprovide breaths in an
intermittent manner, maybestopping every minute or so to
provide a couple of breaths, butthat's probably okay in this
context because the patient isso profoundly hypothermic.
Their metabolic rate is likelyto be very, very low, so their
(37:58):
oxygen consumption is going tobe low.
And we just want to keepcirculating blood, and then
intermittently exchange gases.
So I'd put a Lucas device onthis patient, run it essentially
continuously, and have someonedirect the toboggan team on the
way down to make intermittentstops, provide breaths, and then
resume transport.
(38:19):
A less evidence supportedstrategy for patients who have a
very low body temperature.
And by that, I mean, even lowerthan this patient, less than 28
degrees Celsius is you canconsider intermittent CPR if
there's a risk to the team orit's not technically feasible to
perform continuous CPR, youcould provide two minutes of CPR
(38:42):
and then stop CPR, transport thepatient for a period of time and
resume CPR.
This has been reported at casestudy level in the literature.
It's never been subjected to arandomized trial.
We're never going to get thattrial.
This might be pertinent to ateam that has a prolonged.
Extrication out of the backcountry, and they need to focus
(39:03):
on actually moving that patientbefore nightfall and risk to
rescuers.
And so you might do intermittentCPR, recognizing that this is
definitely not ideal for thepatient's resuscitation, but
that patient also has arelatively low chance of
survival to begin with.
And so the risk to the teamisn't really warranted
(39:26):
defibrillation.
Max three attempts for patientwith core temp, less than 30.
Okay.
epinephrine, hold it until bodytemperature is above 30, so
probably until they get to therewarming center, and then CPR,
we can use continuous CPR with aLucas device, or you might
consider intermittent CPR forthe profoundly hypothermic
(39:47):
patient.
And you don't have to rememberall of this because it's in the
tiny text on the bottom of thatalgorithm.
So that's it for our review ofthe ICAR critically buried
avalanche resuscitationalgorithm.
I hope that the take homes youget from this are that high
quality BLS care remainsimportant for these patients and
(40:08):
that the big changes that wemake to their care hinge around
the duration of burial, signs oflife, evidence of an occluded
airway.
And then if we're performing ALScare, perhaps their core body
temperature and the ability tomonitor their underlying heart
rhythm.
In the majority of situations,we're going to be providing CPR
(40:29):
for these patients until we cantransport them to a definitive
care.
However, there are times in warmpatients who had blocked airways
where we might call it after 20minutes of attempted
resuscitation.
And that's entirely appropriate.
I don't think.
You should be expected to beable to regurgitate this
(40:49):
information in a stressfulsituation.
So if you are potentiallysomeone who would respond to a
critically buried avalanchepatient, if you're a member of a
ski patrol or a search andrescue team, or a flight
resource that does scene callsin the mountains.
I would consider saving thisresource to your phone or
creating a card that you cankeep in your pocket, because
(41:10):
this is a low frequency, buthigh consequence event.
And it's important that we feelgood about the care that we're
providing and provide evidencebased care that gives the right
patients the right chance ofsurvival.
That's it for this episode ofwilderness medicine updates.
Thank you for listening.
I'll be back soon with moremountain medicine content
(41:32):
straight to your ears.
In the meantime, if you enjoythe show, the best way that you
can show your support is toshare the show with someone you
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Pass it along to another doctor,nurse, ski patroller, medical
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And if you have a moment, givethe show a five star review on
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(41:54):
I don't make any money off thisthing, I just pay money, but I'm
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If you want to reach out to me,I always love to hear from
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Best way to do that is to sendme an email at
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(42:16):
Until next time, stay fit, stayfocused, and have fun.
Hello and welcome back to wilderness medicine updates.
I'm your host Patrick Fink.Thisweek, episode 17 resuscitation
of the buried avalanche victim.
Part two, we're going to diveinto the rescue algorithm.
If you haven't listened toepisode 12, I strongly suggest
that you go back and do that.
(00:28):
In that episode, I talk aboutthe physiology that underlies
the resuscitation algorithm.
It explains why we try toresuscitate certain patients and
why we will quit and call it onothers.
So go ahead and take a listen tothat.
In today's episode, I'm going tostart by giving just a quick
review of a couple points.
(00:50):
then we're going to dive intothe resuscitation algorithm.
You can find that ICARinternational committee on
Alpine rescue.
Algorithm in your show notesthere.
If you have the opportunity tolook at it, it might help you
kind of work your way throughthe first half of this show, but
if you don't have it, noproblem.
I think you'll still get a lotout of listening to it.
(01:12):
And so after we go through thatalgorithm, we're going to take a
brief pause, and then we'regoing to jump into a couple
cases that help us illustratehow we might apply this
algorithm to the criticallyburied avalanche victim.
Imogen (01:26):
Review of Avalanche Burial Physiology
Patrick (01:28):
let's start by reviewing how people die in
avalanches.
And in this episode, we're goingto be talking about the
critically buried avalanchevictim.
What does that mean?
We're talking about someone whois buried with their head, their
airway, completely under thesurface of the snow.
And as soon as that happens, theclock is ticking.
If you look at a graph or asurvival curve of buried
(01:53):
avalanche victims, what we seeis that in the first 10 minutes,
about 10 to 20 percent of peopledie.
And the reason for that is thatthey can die of trauma.
They're very unlikely to die ofother causes during that period
of time.
They just haven't been under thesnow for long enough.
So if they're dug out in thefirst 10 minutes and they're
(02:13):
dead, they have no pulse, theyhave no respirations.
They probably died of trauma.
As soon as we get beyond that 10minute mark and extending out to
maybe around 60 minutes, we'renow talking about asphyxia as
the primary cause of death.
So at that 10 minute mark, about80 percent of our buried
avalanche victims are alive.
(02:33):
But as we get out to around 60minutes, the survival curve
drops pretty radically.
It drops well below 20 percentat around 30 minutes, and levels
out at about 10 percent at 60minutes.
So, 80 percent down to the 10%,that's 70 percent of our buried
(02:54):
avalanche victims are going tobe dying of asphyxia.
And that means that theysuccumbed to a lack of oxygen,
or in some rare cases, a veryhigh carbon dioxide level.
Now, who survives beyond 60minutes?
The people who survive beyond 60minutes are the ones who
probably had a very big airpocket.
(03:15):
They had plenty of room toexchange gas with their
environment, and they didn't dieof trauma.
So if we encounter a buriedavalanche victim, who's been
under the snow for more than 60minutes.
We need to think about thepossibility that they could have
died of hypothermia.
We consider hypothermia after 60 minutes.
(03:36):
But, in truth, most peoplearen't going to die of
hypothermia in an avalanchebecause you're just not buried
for long enough, even if it's acouple of hours.
Studies have looked at howquickly people's temperatures
decline under the snow, and it'smaybe 1 to 2 degrees centigrade
every hour.
That's really slow, particularlyif we're talking about critical
(03:57):
hypothermia with a temperatureof less than 30, getting there
from a normal body temperatureof around 36, we're talking
about maybe 3 hours.
Now, there are some, uniquecases if you're in a creek, if
you're really wet, you mightincrease conductivity and
cooling.
So, we do allow for thepossibility that a buried
avalanche victim may behypothermic.
(04:19):
And those people can survive asurprisingly long period of
time.
Now that we've reviewed howpeople die in avalanches, let's
talk about critical determinantsof survival.
So, these are the things that wewant to assess.
In the back of our mind, we'reactively recording when we're
rescuing an avalanche victim.
(04:41):
The first critical determinantof survival is the duration of
the avalanche burial.
Namely, at what time did theavalanche occur?
And at what time did thepatient's head and airway get
accessed and pulled out of thesnow?
The reason that this isimportant is because that is
going to help us determine, dowe think this patient likely
(05:02):
died of asphyxia?
Or do we need to be consideringhypothermia as well?
If we're digging the patient outin under 60 minutes, the
likelihood that hypothermia isthe cause of their cardiac
arrest is very low.
So when we're rescuing apatient, we want to know what
time the avalanche occurred, andwe want to take note when we
finally get to the head.
(05:24):
Then, when we get to the head,there's the second critical
determinant of survival, whichis the patency of the airway.
I'm not talking about thepresence of an air pocket around
the patient's head, and that'soften hard to evaluate when,
you're going after him with ashovel, and maybe someone
stepped near the head, But whenyou access the patient's face,
are both the nose and mouthcompletely occluded with snow?
(05:47):
Are they blocked?
Are they packed?
And the reason for that, go backto episode 15 and look at the
research around airway patencyin avalanche victims.
The survival of a buriedavalanche victim is very low
beyond 15 minutes in peoplewhose mouths and noses are
packed with snow.
And that's because if you haveno chance of exchanging gas with
(06:09):
your surroundings, you're goingto die of asphyxia in like eight
minutes, no hope.
So that's something else we wantto take note of as we're
resuscitating our patient.
Another no brainer, criticaldeterminants of survival, that
does factor into our algorithm,is does the patient have signs
of life?
When we pull them out of thehole, do they exhibit signs of
life?
(06:29):
And what do we consider signs oflife?
So, obviously, if they're alert,they're alive.
But if they have any kind ofverbal or, motor response to
pain, they're alive.
Any movement at all.
Any breathing.
A palpable pulse.
We consider those signs of lifeand those patients who have
(06:51):
signs of life are treateddifferently in our resuscitation
algorithm.
Finally, when we access thatpatient, there's the fourth
critical determinant ofsurvival, which is, does the
patient have a clearly lethalinjury?
These are the patients whoclearly died of trauma, and we
are not going to subject ourteam to the trauma and the
(07:12):
difficulty of resuscitating thatpatient or trying to, if they
have a clearly lethal injury,what is a clearly lethal injury?
The two which we include hereare decapitation, the head is
not connected to the body, ortruncal transection, they've
been cut in half.
The algorithm also includesevidence of decomposition, but
(07:35):
clearly this applies just toprofessional teams who are
perhaps retrieving a body afterseveral days.
So not so relevant to theaverage rescuer.
So to recap, in the first 10minutes, people die of trauma.
In the next 50, out to about 60minutes.
(07:58):
We generally assume that theydied of a lack of air or
asphyxia.
And then if they've been buriedlonger than 60 minutes and they
have a patent airway in an airpocket, perhaps we start
thinking, Oh, maybe hypothermiais a factor.
And when we access that patient,when we actually reach their
face, we're going to take noteof the time and how long it has
been since the avalancheoccurred.
That's our duration of burial.
(08:18):
We're going to check their noseand mouth.
That's our airway patency.
Is it blocked with snow or is itopen?
And then we're going to evaluatethat patient for signs of life.
Are they alert?
Are they speaking?
Do they exhibit any motorresponse to pain or verbal
prompting?
Are they breathing?
And do they have a pulse?
And we're going to do a reallyquick evaluation to say, Hey, do
(08:42):
they have a clearly lethalinjury?
And then we're going to applythe algorithm.
Imogen (08:51):
The Basic Life Support Algorithm
Patrick (08:53):
This international committee on Alpine rescue
algorithm, the ICAR Algorithmfor the resuscitation of the
critically buried avalanchevictim begins with basic life
support care.
It doesn't matter if you're anALS provider or a BLS provider,
you're going to be providing BLScare when you first access the
patient.
(09:13):
If you're looking at thealgorithm, you're going to see
that there are places to recordcertain critical pieces of
information.
We really want to know the timeof the avalanche.
When we expose the patient'shead and was the airway
obstructed.
And from that, we can derive theduration of burial.
So as the BLS provider reachingthe patient, you're going to
perform your initial assessment.
(09:34):
You're going to access theairway and you're going to
assess for signs of life.
If the patient is moving,they're alive.
If they are breathingspontaneously.
Then we can treat them accordingto normal trauma and hypothermia
care.
We're going to handle themgently.
We're going to take precautionsagainst spinal trauma.
We're going to treat hypothermiaas appropriate.
(09:55):
We're going to transport thatpatient to a hospital for
further evaluation.
But if this patient is notexhibiting signs of life.
Then we're going to startproceeding down our BLS pathway.
And the first decision point onthis BLS pathway is how long was
the patient buried?
We divide this into a burialduration of less than 60 minutes
(10:18):
and a burial duration of longerthan 60 minutes.
The reason for that to reiterateis that if someone is buried
less than 60 minutes, we assumethat their cause of death.
The cause of death that we couldpotentially reverse would be
asphyxia.
However, if it's greater than 60minutes, then we're thinking,
Hey, maybe hypothermia is atplay.
So let's talk about less than 60minutes.
(10:40):
First, if someone has beenburied for less than 60 minutes,
we are presuming asphyxia as thecause of cardiac arrest.
And we're going to check forsigns of life for no more than
10 seconds because the clock isticking.
They are perhaps asphyxiating.
We do not want to wait too long.
If there are no signs of lifeand we have checked for 10
seconds, then we're going tobegin with giving 5 rescue
(11:01):
breaths.
The reason we go to the rescuebreath first is that we're
treating asphyxia, so deliveringbreaths is our priority.
Then, without hesitation, we'regoing to begin CPR.
Now, for a burial duration ofgreater than 60 minutes, Our
presumed cause of death ispotentially hypothermia.
In this case, we're going tocheck for signs of life for up
(11:23):
to one minute.
Why is that one minute insteadof 10 seconds?
The reason for that is thatsomeone who is profoundly
hypothermic can have profoundlyslow vital signs, perhaps one a
minute or a heart rate of six.
(11:45):
If they have any signs of life,then we are going to treat them
just like the other patient.
We're going to treat them withappropriate trauma and
hypothermia care.
We're going to handle themgently because hypothermia can
make people very fragile.
Their hearts get very grumpy.
We're going to take precautionsagainst trauma.
(12:06):
And we're going to transportthem to hospital.
But, if there are no signs oflife in this patient who's been
buried for greater than 60minutes with presumed possible
hypothermia, The next questionthat we have is, is EKG
monitoring possible?
If so, slap that on.
But start CPR now.
(12:26):
There is only one caveat to bothof these pathways, which is we
are not going to start CPR ifthe burial duration has been
greater than 60 minutes, andthey have an obstructed airway,
and that EKG monitor that wejust got shows asystole.
The reason for that is thatthey've been buried a long time,
(12:48):
their airway is blocked, theyalmost certainly succumbed of
hypoxia, and they are showingthe heart rhythm consistent with
that, which is no heart rhythm.
Any other heart rhythm likeventricular fibrillation or
pulseless electrical activity,PEA, an unknown heart rhythm we
don't have monitoring available,we're still going to continue to
(13:09):
resuscitate that patient.
Burial duration, over 60minutes.
Airway blocked with snow,asystole on the monitor, we're
calling it.
That concludes the BLSalgorithm.
To reiterate, we want to performour initial assessment, and then
we're going to divide thepatients based on whether they
were buried for less than orgreater than 60 minutes.
(13:31):
If they were buried for lessthan 60 minutes, we presume that
they were asphyxiated, we checkfor signs of life for 10
seconds, and then we begin CPR.
If they were buried for greaterthan 60 minutes, we think
hypothermia is possible, and wecheck for signs of life for up
to a minute.
If they're not present, then wereally want that EKG monitor,
but we're going to begin CPRalso in this setting.
(13:54):
If you're a BLS provider, we'renot going to call it.
We're not going to quit on thispatient.
Once CPR has started, they needto be.
transported to either an ALSprovider or they need to go to
hospital.
And the reason for that is thatthere are a small subset of
these patients who couldpotentially survive.
And so we don't have the toolsto call it in the field as a BLS
(14:15):
provider alone, unless there'sthat burial duration over 60
minutes, plugged airwayasystole.
Now, if you have ALS resources,we algorithm to the ALS care.
Imogen (14:30):
The advanced life support algorithm
Patrick (14:32):
Our ALS algorithm begins.
with the same BLS care.
It's the exact same algorithmuntil we reach the point at
which we just concluded, wherewe have started CPR.
We want to know burial duration,airway patency, we're checking
for signs of life, we'restarting CPR.
But then as that ALS provider,we're hopefully arriving with a
(14:53):
few extra tools.
And those tools are the abilityto monitor the patient's heart
rhythm, and ideally the abilityto measure the patient's
esophageal temperature.
We want to know a core bodytemperature.
So, as that ALS providerarriving on scene, CPR is going
to continue while we make someadditional determinations.
(15:13):
We want to measure theesophageal temperature as soon
as possible, and we want to findout the heart rhythm.
We can now move to page two ofthis two page algorithm if
you're playing along at home.
The simpler side of thisalgorithm is for patients who
are buried less than 60 minutesbecause they are the ones who
have presumed asphyxia.
There are fewer things that wemight do for this patient and
(15:36):
fewer reasons why we might tryto resuscitate for longer.
So, let's start with the burialduration of less than 60
minutes.
As that ALS provider, you thenmeasure an esophageal
temperature if you can.
If the patient's temperature isgreater than 30 degrees Celsius,
if they do not have criticalhypothermia, or if we can't
(15:56):
measure their temperature, thispatient who has been buried for
less than 60 minutes shouldprobably receive about 20
minutes of CPR.
And if that is not successful,we'll consider terminating CPR,
because that patient likelysuccumbed due to hypoxia and
with a warm enough core bodytemperature, we're not risking
missed hypothermic arrest.
(16:19):
Note that in this case, if thetemperature is unknown, the
algorithm also recommends thatwe don't necessarily perform
prolonged CPR, and that'sbecause the likelihood that this
patient is hypothermic afterthis short period of time And is
deserving of prolongedresuscitation is really low.
They say consider becausethere's always going to be some
kind of extenuatingcircumstance, but we'll consider
(16:41):
terminating.
How about if you get thattemperature and it's less than
30 degrees Celsius.
So they've been buried less than60 minutes, but they're cold,
cold, cold, cold.
They have severe hypothermia.
Maybe they were hypothermicbefore they got buried.
If that's the case, then CPRshould continue until they can
(17:01):
go to hospital.
If you have a choice ofhospitals, you should transport
them to a hospital with ECLS,which is called extracorporeal
life support.
That's a heart lung machine orECMO.
That's how we warm up theseverely hypothermic patient.
So if the patient is reallycold, CPR should continue.
(17:22):
A good rule of thumb here isthat someone is not dead until
they are warm and dead.
That's it, pretty simple, so forthe ALS provider, that less than
60 minute burial, if they'recold, they go to hospital with
continuing CPR, if they're not,we're going to work for 20
minutes or so and then considerterminating.
(17:44):
Let's turn our attention to theslightly more complicated burial
duration of more than 60minutes.
For the patient who's beenburied more than 60 minutes,
hypothermia is now apossibility.
Because of that, we really wantto see the EKG tracing.
This is someone that we justpulled out of the snow, who has
been buried for more than 60minutes, and they're not showing
(18:05):
signs of life, but theprofoundly hypothermic patient
can be sort of like Han Solo ina block of carbonite.
It could be kind of a suspendedanimation situation.
So we really want to see thatEKG tracing, And the rhythm is
pulseless electrical activity,some kind of organized rhythm on
the monitor, but no pulse.
Or we see ventricularfibrillation.
(18:28):
Or we can't determine what therhythm is.
Basically anything but asystole.
Then we move to our sametemperature dichotomization.
And the reason for that is thatthese abnormal heart rhythms in
the presence of a very coldtemperature is consistent with
severe hypothermia.
They can also be signs andsymptoms of asphyxia.
(18:50):
So again, if the patient is verycold, they're going to be
transported to hospital, theyhave any kind of rhythm on the
monitor, they're very cold.
They're going to the hospitalwith ongoing CPR in this group.
However, the patients who havebeen buried for longer than 60
minutes, if we don't know thetemperature.
(19:10):
And they have any heart rhythmbut asystole, they also should
go to the hospital.
Because we think that, okay,that's a subset of people who
might be hypothermic, we justcan't tell.
They deserve a chance.
They should go to hospital withongoing CPR.
But if they've got ventricularfibrillation, PEA, anything but
asystole, or we don't know theirrhythm, and their temperature is
greater than 30 degrees Celsius,we're gonna quit after 20
(19:33):
minutes, just like before.
We would consider termination ifwe don't get return of
spontaneous circulation or ROSCafter 20 minutes.
That's because if they're notprofoundly hypothermic, that V
fib, that PEA is probably due toasphyxia, and we're not going to
resuscitate someone who has achance of walking out of the
hospital neurologically intact.
(19:57):
But let's say, okay, rewind.
This is a patient who's beenburied for 60 minutes.
We throw those pads on, we haveC through AED, or we have a 3
lead, and we're looking at theelectrical activity of the
heart, and there is none.
There is asystole.
Well, now the question is, wasthis a witnessed cardiac arrest?
(20:18):
Weird question, right?
For the critically buriedavalanche victim.
This applies to an interestingsubset of patients.
The answer to this is probablyno, no one saw them go into
arrest under the snow.
However, there may be a set ofpatients where we dig them out.
They have signs of life.
They've been under there a longtime and then they walk a little
bit.
They walk away from that holeand then they collapse into
(20:39):
cardiac arrest.
there's the possibility forwhat's called after drop, which
is where the blood in theextremities is super cold.
And so this patient who'sborderline profoundly
hypothermic, as soon as theystart getting up, moving around,
becomes profoundly hypothermicand goes into cardiac arrest.
So if it was a witnessed cardiacarrest, we're going to do the
same thing.
We're going to measure theesophageal temperature and if
(21:00):
they're cold or it's unknowntemperature, we're going to
transport them.
But if they're warm, we're goingto work them for 20 minutes and
then call it.
The more common situation isthis was not a witnessed cardiac
arrest.
They died at some pointunderneath the snow.
Then our question is, was thereairway obstructed?
(21:20):
We're taking note of that.
When we first reached thepatient, If the airway is
obstructed, an there is an EKGthat shows asystole in an
unwitnessed cardiac arrest insomeone who's been buried for
over 60 minutes, we're gonnacall it.
They've been buried a long time,they have no heart activity,
their airway's blocked, meaninga very high probability of
asphyxia.
(21:41):
There is no point in continuingthat resuscitation.
If their airway was open, Or wedon't know because no one
actually looked, because it wasa chaotic scene.
Then we're going to apply thetemperature algorithm again.
We're going to check for atemperature less than 30, or if
we don't know it, we're going todo CPR until we get him to the
hospital.
(22:01):
The reason that we're taking allthese people who have a
temperature less than 30 to thehospital is that they're
refrigerated.
Their metabolic state has beenreally low.
There is a chance of a goodneurological outcome.
If they can be warmed andprotected, some of them will
walk out neurologically intact,even if they've been buried for.
(22:21):
An hour, two hours.
If you're playing along at homewith the ALS algorithm in front
of you, you'll see that afterarrival to the hospital, there's
another square and that's tomeasure potassium and calculate
a hope score.
I'm going to just address thatsuper briefly because it is not
relevant to the field care ofmost avalanche victims.
(22:42):
Unless you live in a magicalworld where you have point of
care, potassium testing out inthe field, basically, if the
potassium level is super high,That suggests cellular death,
and those patients do not dowell even if we warm them up.
And then the HOPE score is ascore that helps determine
(23:03):
survival after extracorporeal rewarming, and it helps us decide
in hospital who deserves thoseadvanced interventions, which
can be very expensive, veryinvasive.
And, do pose some risk toproviders, like needle sticks,
procedures, that kind of thing.
And we don't want people to endup on a heart lung machine with
a dead brain because that justcreates distress for the family.
(23:25):
So we, we try to decide who isbest to resuscitate in hospital
using a point of care potassiumand the HOPE score.
But that's a subject for anotherday.
So going back to high level asan ALS provider, you're going to
do the same.
BLS stuff.
We're checking for signs oflife, taking note of how long
(23:47):
the patient's been buried, andwe're starting CPR.
But our goal is to get an ECGmonitor on there.
And if we can to check thepatient's temperature, then
we're dividing our care based onwhether it was a short burial or
a long burial.
If it was a short burial, great.
We are going to measure thatpatient's temperature and we're
going to bias towardsterminating.
Essentially, if we don't knowthe temperature, we're going to
(24:09):
terminate after 20 minutes, orif it's over 30 degrees, we're
going to terminate after 20minutes.
anyone whose core temperature isless than 30, they go to
hospital.
if it's a burial duration ofgreater than 60 minutes, or we
don't know how long the patientwas buried, then we're going to
start dividing based on EKG,witness cardiac arrest, and
(24:30):
airway patency.
People who have V fib or PEA oran unknown rhythm, we divide
based on temperature.
A witness cardiac arrest, wedivide based on temperature.
PEA and a patent airway, wedivide based on temperature.
And these people have beenburied a long time, but we don't
(24:53):
know their temperature.
We bias towards taking them tothe hospital.
We transport with CPR.
That's the main difference incomparison to the less than 60
minutes group.
And finally, if the EKG shows asystole, it was an unwitnessed
arrest.
The airway was obstructed withsnow.
We're going to terminate CPRbecause the likelihood of
survival is low.
(25:16):
All right.
We did it.
We got through the BLS and theALS algorithms.
Let's take a short musicalinterlude and then we'll dive
back in with a couple of casesto apply the algorithm.
Imogen (25:39):
on to the rescue scenarios
Patrick (25:40):
as we worked through the scenarios.
I want you to think about whatyou would do and how you would
approach.
This case that we're talkingabout.
When you hear this.
The sound.
Think about what.
You would want to know, or theactions that you would take
next?
Imogen (26:00):
Case 1
Patrick (26:03):
So you're out with a ski partner as a group of two.
There's been a persistent slabproblem, maybe 50 centimeters
deep.
In the snowpack.
But the difficulty of triggeringit has been increasing.
Over the last few weeks.
So for better for worse today,you've.
Been stepping out into biggerterrain.
Skiing and Alpine bowl andworking.
And your runs further into thebowl.
(26:24):
On the third run.
Your partner's keys first andtriggers a large slab avalanche.
You know, at the point lastseen, but you don't see your
partner and you can't.
I can't hear him when the debrissettles.
You note the time of the.
Avalanche conduct a beaconsearch.
Locate a signal with the lowestpoint at 1.2 meters.
(26:45):
Digging aggressively.
Only into the debris from about1.5 meters, downhill of your
probes.
Probe strike you, reach yourpartners face.
What do you want to know?
And what do you Want to do.
First.
Check the time note the durationof the burial.
And this case, let's say He'sbeen buried for 20 minutes.
(27:07):
As you reach his face, yourpartner doesn't have an air
pocket around it, but.
His mouth and nose.
Aren't blocked with snow.
They're open.
He doesn't.
Have any obviously fatal,traumatic injury.
And you get them out onto.
a small platform he's flat onhis back.
Let's.
Pause and think about where weare and the algorithm.
20 minute burial open airway.
(27:27):
We're proceeding down the lessthan 60 minutes, burial.
Pathway.
What do you assume?
Is the potential.
I will cause.
Of arrest.
And what are your next Fewactions.
The presumed cause of death.
If your partner looks dead, is.
(27:48):
Uh, we'll check for signs oflife for, at most.
10 seconds because he's beenburied for less than 60 minutes.
He has no.
Signs of life, no movement, nobreathing, no pulse.
We give five.
Rescue breaths and start CPR.
Now we're in a tough situation.
We're doing CPR solo.
Calling for help.
(28:09):
Isn't likely to do anything forour partner.
Because of the time needed.
For any.
Help to arrive.
How long should we keepresuscitating him?
In general.
And to be clear, this isoutside.
The guideline because it doesn'tdirectly address partner rescue.
(28:29):
I think.
That 20 to 30 minutes of CPR isthe most that should be
attempted.
There's a few reasons for this.
Uh, survival after.
For a longer period of CPR isvery unlikely.
Increasingly unlikely.
And CPR quality is likely todrop off.
Uh, pretty quickly with a singlerescuer.
It is hard work to do good CPR.
(28:51):
We tire out.
And the effort of.
Doing CPR for a longer can startto compromise the safety of the
rescuer.
Causing exhaustion, sweating,increasing risk of hypothermia,
et cetera.
So those are all reasons not tocontinue.
Longer than about 20 to 30minutes.
Of course, I'm never going totell you that you.
You shouldn't do it longer.
(29:12):
And you'd be hard pressed tostop on.
On a loved one.
But this is a happy podcast.
At.
Least for now.
So in this case, your partnerstarts trying to breathe.
And you check for a pulse and henow has a pulse, but he remains
unresponsive.
where do you go from there?
(29:34):
We're going beyond.
The algorithm now, but mypriorities would be these first
call for help.
There's no way I'm getting himout alone.
We need to be careful.
Careful with him and traumaremains a possibility.
So do a Thorough secondary examand make sure he's not bleeding.
I'd make sure that.
That is.
Breathing seems adequate, youknow, 10 to 12 breaths per
(29:54):
minute.
I'm not Going to have tosupplement his breathing.
Then I'm going to start.
Protecting him because we'regoing to be there for a while.
I want to get him off the snowonto something.
Insulating cover him withlayers.
Hopefully not, but maybe.
Think about what's going tohappen.
If I have to spend the night.
I'd better hope help.
Is coming.
I'm going to reevaluatefrequently and be.
(30:15):
We prepared.
Should he rearrest?
It's unlikely.
Unless it becomes hypothermic,but I don't know what I have
with me here.
So that concludes the first casepartner rescue.
Less than 60 minutes.
We assume that if our partner.
is not breathing and shows nosigns of life has no pulse.
But the cause of death that wecan potentially reverse as this
(30:37):
fixture.
And to review, we're going tocheck for.
Signs of life for no more than10 seconds.
We're going to get five rescuebreaths start.
Start CPR and continuing thatCPR for somewhere between 20 and
30 minutes.
And if we get return ofspontaneous circulation, hurrah,
Our lives.
Just got much more complicated.
We're going to need to thinkabout our next steps.
So that's.
Simple simple enough.
(30:59):
Let's move on to case two.
Imogen (31:01):
Case 2
You're working as a professionalski patroller at a large ski
resort in the Pacific Northwest.
It's early spring, the first bigwarm up of the year, and the sun
is shining.
The avalanche cycle that wasoccurring on the February rain
crest has been quiet for morethan a month, and you've been
getting bored of ski cuttingsmall windslabs.
(31:24):
However, around 2 p.
m., you receive a report of apossible avalanche in the upper
bowl of the resort.
The reporting party reports thata cornice fell, And caused an
avalanche above a traverse andthat multiple skiers and riders
were below the avalanche.
The radio dispatcher sends allavailable resources to the scene
and an organized rescue begins.
(31:45):
A hasty beacon search reveals nosignals, but a witness confirms
that the three victims wereburied.
A probe line begins searchingand you arrive at the scene as
the ALS lead.
You can see that the cornicefall triggered a deep wet slab
on the February raincrust and alarge pile of big blocky debris
is below.
Use stage to respond to victimsas they're located.
(32:08):
Critically Buried Victim 1.
Patrick (32:12):
The first probe strike happens about 20 minutes after
the avalanche, and the patientis excavated and exposed at 26
minutes.
You arrive to the scene with CPRongoing.
What do you want to know?
This is an approximately 22 yearold male snowboarder.
Burial time was 26 minutes, andhis airway was not blocked with
(32:34):
snow.
You slide in an esophagealtemperature probe, and his body
temperature is 35 degreesCelsius.
CPR is ongoing.
What next?
CPR should continue for at least20 minutes.
After 10 minutes of CPR, ROSC isobtained.
(32:55):
Success! You assist in post ROSCcare, including trauma
evaluation and packaging.
But you must now turn yourattention away, because you're
called to.
Imogen (33:04):
Critically Buried Victim 2.
Patrick (33:07):
The second victim is excavated after 65 minutes.
You arrive on the scene, and CPRhas already been started.
What do you want to know?
This is a 45 year old femaleskier.
Burial time was 65 minutes, andher airway was occluded with
snow.
What next?
(33:32):
You instruct your patrolcolleagues to continue CPR.
You place three lead electrodes,and during the next CPR pause,
you note that the patient is inasystole.
CPR resumes.
So, to summarize, this patienthas been buried for more than 65
minutes.
has no palpable pulse, hasongoing CPR, and the underlying
(33:52):
rhythm is asystole.
What do you do?
Unfortunately, this 65 minuteburial with asystole, in a woman
who had an occluded airway, hasno hope of survival.
You instruct your colleagues tocease CPR, and you explain your
reasoning.
(34:13):
But there's no time yet todebrief, Because the probe line
has uncovered.
Imogen (34:17):
Critically Buried Victim 3.
You already know the informationyou want to know right away, so
I'll give it to you.
This is a 36 year old male skierwearing wet jeans and a cotton
hoodie.
He has been buried for 90minutes.
The team noticed a large airpocket when he was excavated,
and his airway was open.
(34:38):
He is unresponsive, has nopulse, and CPR is ongoing.
What are your next actions?
Now, you're no seasoned pro atthis, but you do have a little
laminated copy of the algorithm.
So, like a boss.
You hook him up to a 3 lead, andwhile waiting for a CPR pause,
(34:59):
you slide in an esophagealtemperature probe.
At the next pulse check, heremains pulseless.
He's in ventricularfibrillation.
His core temperature is 29degrees Celsius.
What are your next actions?
And are there any changes thatyou need to make to your
standard cardiac arrest care forthis hypothermic patient?
(35:22):
You defibrillate him and havethe team resume CPR.
You inform dispatch that youneed an air rotor resource to
transport this patient to anECLS capable hospital with CPR
ongoing.
For You have a somewhatprolonged toboggan transport
ahead of you.
He remains in V fib.
He remains in ventricularfibrillation.
(35:46):
This gives us a chance to talkabout a few extra credit points
for the care of these severelyhypothermic avalanche victims.
We're gonna briefly coverdefibrillation, epinephrine, and
what's called intermittent CPR.
Ventricular fibrillation in theprofoundly hypothermic patient
is due to cardiac irritabilityfrom the very low temperature.
Those heart cells just don'tlike that low, low, low
(36:08):
temperature.
So defibrillation may beunsuccessful until the patient
is warmed, and excessiveattempts at defibrillation can
be harmful to that heart muscle.
So for patients with a coretemperature of less than 30
degrees Celsius, we will limitthe number of defibrillation
attempts to three tries untilthe patient is warmed.
So if that patient remains inventricular fibrillation after
(36:30):
three attempts, We're not goingto shock further, we're just
going to continue CPR until wecan warm up the patient.
For the same reason, instead ofgiving multiple rounds of
epinephrine like you might in anormal cardiac arrest, We should
withhold epinephrine until thatcore temperature is greater than
30 degrees Celsius.
This is because the epinephrinecan increase the cardiac
irritability and make it harderto terminate the ventricular
(36:52):
fibrillation, which is itselfprimarily due to the very low
temperature.
So this patient that we'retransporting in V fib, we might
shock them up to three times,but we're not going to give them
any drugs.
Now I mentioned that we have aprolonged transport and this
patient has CPR ongoing, so whatare our options there?
The first and riskiest option isto try to put a patroller in the
(37:14):
toboggan performingcompressions.
That doesn't work well.
CPR quality is likely to be low,and there's significant risk to
the patroller performing thecompressions while you move, and
changing patrollers in and outis tough.
my hope is that in thissituation you might have access
to mechanical CPR.
I'm talking about a Lucas typedevice.
(37:35):
That device would allowcompressions to continue in an
ongoing manner while the patientis transported.
You're only going to be able toprovide breaths in an
intermittent manner, maybestopping every minute or so to
provide a couple of breaths, butthat's probably okay in this
context because the patient isso profoundly hypothermic.
Their metabolic rate is likelyto be very, very low, so their
(37:58):
oxygen consumption is going tobe low.
And we just want to keepcirculating blood, and then
intermittently exchange gases.
So I'd put a Lucas device onthis patient, run it essentially
continuously, and have someonedirect the toboggan team on the
way down to make intermittentstops, provide breaths, and then
resume transport.
(38:19):
A less evidence supportedstrategy for patients who have a
very low body temperature.
And by that, I mean, even lowerthan this patient, less than 28
degrees Celsius is you canconsider intermittent CPR if
there's a risk to the team orit's not technically feasible to
perform continuous CPR, youcould provide two minutes of CPR
(38:42):
and then stop CPR, transport thepatient for a period of time and
resume CPR.
This has been reported at casestudy level in the literature.
It's never been subjected to arandomized trial.
We're never going to get thattrial.
This might be pertinent to ateam that has a prolonged.
Extrication out of the backcountry, and they need to focus
(39:03):
on actually moving that patientbefore nightfall and risk to
rescuers.
And so you might do intermittentCPR, recognizing that this is
definitely not ideal for thepatient's resuscitation, but
that patient also has arelatively low chance of
survival to begin with.
And so the risk to the teamisn't really warranted
(39:26):
defibrillation.
Max three attempts for patientwith core temp, less than 30.
Okay.
epinephrine, hold it until bodytemperature is above 30, so
probably until they get to therewarming center, and then CPR,
we can use continuous CPR with aLucas device, or you might
consider intermittent CPR forthe profoundly hypothermic
(39:47):
patient.
And you don't have to rememberall of this because it's in the
tiny text on the bottom of thatalgorithm.
So that's it for our review ofthe ICAR critically buried
avalanche resuscitationalgorithm.
I hope that the take homes youget from this are that high
quality BLS care remainsimportant for these patients and
(40:08):
that the big changes that wemake to their care hinge around
the duration of burial, signs oflife, evidence of an occluded
airway.
And then if we're performing ALScare, perhaps their core body
temperature and the ability tomonitor their underlying heart
rhythm.
In the majority of situations,we're going to be providing CPR
(40:29):
for these patients until we cantransport them to a definitive
care.
However, there are times in warmpatients who had blocked airways
where we might call it after 20minutes of attempted
resuscitation.
And that's entirely appropriate.
I don't think.
You should be expected to beable to regurgitate this
(40:49):
information in a stressfulsituation.
So if you are potentiallysomeone who would respond to a
critically buried avalanchepatient, if you're a member of a
ski patrol or a search andrescue team, or a flight
resource that does scene callsin the mountains.
I would consider saving thisresource to your phone or
creating a card that you cankeep in your pocket, because
(41:10):
this is a low frequency, buthigh consequence event.
And it's important that we feelgood about the care that we're
providing and provide evidencebased care that gives the right
patients the right chance ofsurvival.
That's it for this episode ofwilderness medicine updates.
Thank you for listening.
I'll be back soon with moremountain medicine content
(41:32):
straight to your ears.
In the meantime, if you enjoythe show, the best way that you
can show your support is toshare the show with someone you
think would enjoy it.
Pass it along to another doctor,nurse, ski patroller, medical
student, EMT, paramedic, SARmember, skiing buddy, family
member.
And if you have a moment, givethe show a five star review on
Apple Podcasts or Spotify.
(41:54):
I don't make any money off thisthing, I just pay money, but I'm
putting in the time, putting inthe effort, and the more people
it reaches, the happier I am.
If you want to reach out to me,I always love to hear from
listeners of the show withcomments, questions, or ideas
for future shows.
Best way to do that is to sendme an email at
wildernessmedicineupdates atgmail.
com and I'll get back to yousoon.
(42:16):
Until next time, stay fit, stayfocused, and have fun.
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