Ep. 17 - Resuscitation of the Buried Avalanche Victim, Part 2: The Rescue Algorithm

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.

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Transcript

Patrick: 0:08

Hello and welcome back to wilderness medicine updates. I'm your host Patrick Fink.This week, episode 17 resuscitation of the buried avalanche victim. Part two, we're going to dive into the rescue algorithm. If you haven't listened to episode 12, I strongly suggest that you go back and do that. In that episode, I talk about the physiology that underlies the resuscitation algorithm. It explains why we try to resuscitate certain patients and why we will quit and call it on others. So go ahead and take a listen to that. In today's episode, I'm going to start by giving just a quick review of a couple points. then we're going to dive into the resuscitation algorithm. You can find that ICAR international committee on Alpine rescue. Algorithm in your show notes there. If you have the opportunity to look at it, it might help you kind of work your way through the first half of this show, but if you don't have it, no problem. I think you'll still get a lot out of listening to it. And so after we go through that algorithm, we're going to take a brief pause, and then we're going to jump into a couple cases that help us illustrate how we might apply this algorithm to the critically buried avalanche victim.

Imogen: 1:26

Review of Avalanche Burial Physiology

Patrick: 1:28

let's start by reviewing how people die in avalanches. And in this episode, we're going to be talking about the critically buried avalanche victim. What does that mean? We're talking about someone who is buried with their head, their airway, completely under the surface of the snow. And as soon as that happens, the clock is ticking. If you look at a graph or a survival curve of buried avalanche victims, what we see is that in the first 10 minutes, about 10 to 20 percent of people die. And the reason for that is that they can die of trauma. They're very unlikely to die of other causes during that period of time. They just haven't been under the snow for long enough. So if they're dug out in the first 10 minutes and they're dead, they have no pulse, they have no respirations. They probably died of trauma. As soon as we get beyond that 10 minute mark and extending out to maybe around 60 minutes, we're now talking about asphyxia as the primary cause of death. So at that 10 minute mark, about 80 percent of our buried avalanche victims are alive. But as we get out to around 60 minutes, the survival curve drops pretty radically. It drops well below 20 percent at around 30 minutes, and levels out at about 10 percent at 60 minutes. So, 80 percent down to the 10%, that's 70 percent of our buried avalanche victims are going to be dying of asphyxia. And that means that they succumbed to a lack of oxygen, or in some rare cases, a very high carbon dioxide level. Now, who survives beyond 60 minutes? The people who survive beyond 60 minutes are the ones who probably had a very big air pocket. They had plenty of room to exchange gas with their environment, and they didn't die of trauma.

3:22

So if we encounter a buried avalanche victim, who's been under the snow for more than 60 minutes. We need to think about the possibility that they could have died of hypothermia.

Patrick: 3:32

We consider hypothermia after 60 minutes. But, in truth, most people aren't going to die of hypothermia in an avalanche because you're just not buried for long enough, even if it's a couple of hours. Studies have looked at how quickly people's temperatures decline under the snow, and it's maybe 1 to 2 degrees centigrade every hour. That's really slow, particularly if we're talking about critical hypothermia with a temperature of less than 30, getting there from a normal body temperature of around 36, we're talking about maybe 3 hours. Now, there are some, unique cases if you're in a creek, if you're really wet, you might increase conductivity and cooling. So, we do allow for the possibility that a buried avalanche victim may be hypothermic. And those people can survive a surprisingly long period of time. Now that we've reviewed how people die in avalanches, let's talk about critical determinants of survival. So, these are the things that we want to assess. In the back of our mind, we're actively recording when we're rescuing an avalanche victim. The first critical determinant of survival is the duration of the avalanche burial. Namely, at what time did the avalanche occur? And at what time did the patient's head and airway get accessed and pulled out of the snow? The reason that this is important is because that is going to help us determine, do we think this patient likely died of asphyxia? Or do we need to be considering hypothermia as well? If we're digging the patient out in under 60 minutes, the likelihood that hypothermia is the cause of their cardiac arrest is very low. So when we're rescuing a patient, we want to know what time the avalanche occurred, and we want to take note when we finally get to the head. Then, when we get to the head, there's the second critical determinant of survival, which is the patency of the airway. I'm not talking about the presence of an air pocket around the patient's head, and that's often hard to evaluate when, you're going after him with a shovel, and maybe someone stepped near the head, But when you access the patient's face, are both the nose and mouth completely occluded with snow? Are they blocked? Are they packed? And the reason for that, go back to episode 15 and look at the research around airway patency in avalanche victims. The survival of a buried avalanche victim is very low beyond 15 minutes in people whose mouths and noses are packed with snow. And that's because if you have no chance of exchanging gas with your surroundings, you're going to die of asphyxia in like eight minutes, no hope. So that's something else we want to take note of as we're resuscitating our patient. Another no brainer, critical determinants of survival, that does factor into our algorithm, is does the patient have signs of life? When we pull them out of the hole, do they exhibit signs of life? And what do we consider signs of life? So, obviously, if they're alert, they're alive. But if they have any kind of verbal or, motor response to pain, they're alive. Any movement at all. Any breathing. A palpable pulse. We consider those signs of life and those patients who have signs of life are treated differently in our resuscitation algorithm. Finally, when we access that patient, there's the fourth critical determinant of survival, which is, does the patient have a clearly lethal injury? These are the patients who clearly died of trauma, and we are not going to subject our team to the trauma and the difficulty of resuscitating that patient or trying to, if they have a clearly lethal injury, what is a clearly lethal injury? The two which we include here are decapitation, the head is not connected to the body, or truncal transection, they've been cut in half. The algorithm also includes evidence of decomposition, but clearly this applies just to professional teams who are perhaps retrieving a body after several days. So not so relevant to the average rescuer. So to recap, in the first 10 minutes, people die of trauma. In the next 50, out to about 60 minutes. We generally assume that they died of a lack of air or asphyxia. And then if they've been buried longer than 60 minutes and they have a patent airway in an air pocket, perhaps we start thinking, Oh, maybe hypothermia is a factor. And when we access that patient, when we actually reach their face, we're going to take note of the time and how long it has been since the avalanche occurred. That's our duration of burial. We're going to check their nose and mouth. That's our airway patency. Is it blocked with snow or is it open? And then we're going to evaluate that patient for signs of life. Are they alert? Are they speaking? Do they exhibit any motor response to pain or verbal prompting? Are they breathing? And do they have a pulse? And we're going to do a really quick evaluation to say, Hey, do they have a clearly lethal injury? And then we're going to apply the algorithm.

Imogen: 8:51

The Basic Life Support Algorithm

Patrick: 8:53

This international committee on Alpine rescue algorithm, the ICAR Algorithm for the resuscitation of the critically buried avalanche victim begins with basic life support care. It doesn't matter if you're an ALS provider or a BLS provider, you're going to be providing BLS care when you first access the patient. If you're looking at the algorithm, you're going to see that there are places to record certain critical pieces of information. We really want to know the time of the avalanche. When we expose the patient's head and was the airway obstructed. And from that, we can derive the duration of burial. So as the BLS provider reaching the patient, you're going to perform your initial assessment. You're going to access the airway and you're going to assess for signs of life. If the patient is moving, they're alive. If they are breathing spontaneously. Then we can treat them according to normal trauma and hypothermia care. We're going to handle them gently. We're going to take precautions against spinal trauma. We're going to treat hypothermia as appropriate. We're going to transport that patient to a hospital for further evaluation. But if this patient is not exhibiting signs of life. Then we're going to start proceeding down our BLS pathway. And the first decision point on this BLS pathway is how long was the patient buried? We divide this into a burial duration of less than 60 minutes and a burial duration of longer than 60 minutes. The reason for that to reiterate is that if someone is buried less than 60 minutes, we assume that their cause of death. The cause of death that we could potentially reverse would be asphyxia. However, if it's greater than 60 minutes, then we're thinking, Hey, maybe hypothermia is at play. So let's talk about less than 60 minutes. First, if someone has been buried for less than 60 minutes, we are presuming asphyxia as the cause of cardiac arrest. And we're going to check for signs of life for no more than 10 seconds because the clock is ticking. They are perhaps asphyxiating. We do not want to wait too long. If there are no signs of life and we have checked for 10 seconds, then we're going to begin with giving 5 rescue breaths. The reason we go to the rescue breath first is that we're treating asphyxia, so delivering breaths is our priority. Then, without hesitation, we're going to begin CPR. Now, for a burial duration of greater than 60 minutes, Our presumed cause of death is potentially hypothermia. In this case, we're going to check for signs of life for up to one minute. Why is that one minute instead of 10 seconds? The reason for that is that someone who is profoundly hypothermic can have profoundly slow vital signs, perhaps one a minute or a heart rate of six. 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 with appropriate trauma and hypothermia care. We're going to handle them gently because hypothermia can make people very fragile. Their hearts get very grumpy. We're going to take precautions against trauma. And we're going to transport them to hospital. But, if there are no signs of life in this patient who's been buried for greater than 60 minutes with presumed possible hypothermia, The next question that we have is, is EKG monitoring possible? If so, slap that on. But start CPR now. There is only one caveat to both of these pathways, which is we are not going to start CPR if the burial duration has been greater than 60 minutes, and they have an obstructed airway, and that EKG monitor that we just got shows asystole. The reason for that is that they've been buried a long time, their airway is blocked, they almost certainly succumbed of hypoxia, and they are showing the heart rhythm consistent with that, which is no heart rhythm. Any other heart rhythm like ventricular fibrillation or pulseless electrical activity, PEA, an unknown heart rhythm we don't have monitoring available, we're still going to continue to resuscitate that patient. Burial duration, over 60 minutes. Airway blocked with snow, asystole on the monitor, we're calling it. That concludes the BLS algorithm. To reiterate, we want to perform our initial assessment, and then we're going to divide the patients based on whether they were buried for less than or greater than 60 minutes. If they were buried for less than 60 minutes, we presume that they were asphyxiated, we check for signs of life for 10 seconds, and then we begin CPR. If they were buried for greater than 60 minutes, we think hypothermia is possible, and we check for signs of life for up to a minute. If they're not present, then we really want that EKG monitor, but we're going to begin CPR also in this setting. If you're a BLS provider, we're not going to call it. We're not going to quit on this patient. Once CPR has started, they need to be. transported to either an ALS provider or they need to go to hospital. And the reason for that is that there are a small subset of these patients who could potentially survive. And so we don't have the tools to call it in the field as a BLS provider alone, unless there's that burial duration over 60 minutes, plugged airway asystole. 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 algorithm until we reach the point at which we just concluded, where we have started CPR. We want to know burial duration, airway patency, we're checking for signs of life, we're starting CPR. But then as that ALS provider, we're hopefully arriving with a few extra tools. And those tools are the ability to monitor the patient's heart rhythm, and ideally the ability to measure the patient's esophageal temperature. We want to know a core body temperature. So, as that ALS provider arriving on scene, CPR is going to continue while we make some additional determinations. We want to measure the esophageal temperature as soon as possible, and we want to find out the heart rhythm. We can now move to page two of this two page algorithm if you're playing along at home. The simpler side of this algorithm is for patients who are buried less than 60 minutes because they are the ones who have presumed asphyxia. There are fewer things that we might do for this patient and fewer reasons why we might try to resuscitate for longer. So, let's start with the burial duration of less than 60 minutes. As that ALS provider, you then measure an esophageal temperature if you can. If the patient's temperature is greater than 30 degrees Celsius, if they do not have critical hypothermia, or if we can't measure their temperature, this patient who has been buried for less than 60 minutes should probably receive about 20 minutes of CPR. And if that is not successful, we'll consider terminating CPR, because that patient likely succumbed due to hypoxia and with a warm enough core body temperature, we're not risking missed hypothermic arrest. Note that in this case, if the temperature is unknown, the algorithm also recommends that we don't necessarily perform prolonged CPR, and that's because the likelihood that this patient is hypothermic after this short period of time And is deserving of prolonged resuscitation is really low. They say consider because there's always going to be some kind of extenuating circumstance, but we'll consider terminating. How about if you get that temperature and it's less than 30 degrees Celsius. So they've been buried less than 60 minutes, but they're cold, cold, cold, cold. They have severe hypothermia. Maybe they were hypothermic before they got buried. If that's the case, then CPR should continue until they can go to hospital. If you have a choice of hospitals, you should transport them to a hospital with ECLS, which is called extracorporeal life support. That's a heart lung machine or ECMO. That's how we warm up the severely hypothermic patient. So if the patient is really cold, CPR should continue. A good rule of thumb here is that someone is not dead until they are warm and dead. That's it, pretty simple, so for the ALS provider, that less than 60 minute burial, if they're cold, they go to hospital with continuing CPR, if they're not, we're going to work for 20 minutes or so and then consider terminating. Let's turn our attention to the slightly more complicated burial duration of more than 60 minutes. For the patient who's been buried more than 60 minutes, hypothermia is now a possibility. Because of that, we really want to see the EKG tracing. This is someone that we just pulled out of the snow, who has been buried for more than 60 minutes, and they're not showing signs of life, but the profoundly hypothermic patient can be sort of like Han Solo in a block of carbonite. It could be kind of a suspended animation situation. So we really want to see that EKG tracing, And the rhythm is pulseless electrical activity, some kind of organized rhythm on the monitor, but no pulse. Or we see ventricular fibrillation. Or we can't determine what the rhythm is. Basically anything but asystole. Then we move to our same temperature dichotomization. And the reason for that is that these abnormal heart rhythms in the presence of a very cold temperature is consistent with severe hypothermia. They can also be signs and symptoms of asphyxia. So again, if the patient is very cold, they're going to be transported to hospital, they have any kind of rhythm on the monitor, they're very cold. They're going to the hospital with ongoing CPR in this group. However, the patients who have been buried for longer than 60 minutes, if we don't know the temperature. And they have any heart rhythm but asystole, they also should go to the hospital. Because we think that, okay, that's a subset of people who might be hypothermic, we just can't tell. They deserve a chance. They should go to hospital with ongoing CPR. But if they've got ventricular fibrillation, PEA, anything but asystole, or we don't know their rhythm, and their temperature is greater than 30 degrees Celsius, we're gonna quit after 20 minutes, just like before. We would consider termination if we don't get return of spontaneous circulation or ROSC after 20 minutes. That's because if they're not profoundly hypothermic, that V fib, that PEA is probably due to asphyxia, and we're not going to resuscitate someone who has a chance of walking out of the hospital neurologically intact. But let's say, okay, rewind. This is a patient who's been buried for 60 minutes. We throw those pads on, we have C through AED, or we have a 3 lead, and we're looking at the electrical activity of the heart, and there is none. There is asystole. Well, now the question is, was this a witnessed cardiac arrest? Weird question, right? For the critically buried avalanche victim. This applies to an interesting subset of patients. The answer to this is probably no, no one saw them go into arrest under the snow. However, there may be a set of patients where we dig them out. They have signs of life. They've been under there a long time and then they walk a little bit. They walk away from that hole and then they collapse into cardiac arrest. there's the possibility for what's called after drop, which is where the blood in the extremities is super cold. And so this patient who's borderline profoundly hypothermic, as soon as they start getting up, moving around, becomes profoundly hypothermic and goes into cardiac arrest. So if it was a witnessed cardiac arrest, we're going to do the same thing. We're going to measure the esophageal temperature and if they're cold or it's unknown temperature, we're going to transport them. But if they're warm, we're going to work them for 20 minutes and then call it. The more common situation is this was not a witnessed cardiac arrest. They died at some point underneath the snow. Then our question is, was there airway obstructed? We're taking note of that. When we first reached the patient, If the airway is obstructed, an there is an EKG that shows asystole in an unwitnessed cardiac arrest in someone who's been buried for over 60 minutes, we're gonna call it. They've been buried a long time, they have no heart activity, their airway's blocked, meaning a very high probability of asphyxia. There is no point in continuing that resuscitation. If their airway was open, Or we don't know because no one actually looked, because it was a chaotic scene. Then we're going to apply the temperature algorithm again. We're going to check for a temperature less than 30, or if we don't know it, we're going to do CPR until we get him to the hospital. The reason that we're taking all these people who have a temperature less than 30 to the hospital is that they're refrigerated. Their metabolic state has been really low. There is a chance of a good neurological outcome. If they can be warmed and protected, some of them will walk out neurologically intact, even if they've been buried for. An hour, two hours. If you're playing along at home with the ALS algorithm in front of you, you'll see that after arrival to the hospital, there's another square and that's to measure potassium and calculate a hope score. I'm going to just address that super briefly because it is not relevant to the field care of most avalanche victims. Unless you live in a magical world where you have point of care, potassium testing out in the field, basically, if the potassium level is super high, That suggests cellular death, and those patients do not do well even if we warm them up. And then the HOPE score is a score that helps determine survival after extracorporeal re warming, and it helps us decide in hospital who deserves those advanced interventions, which can be very expensive, very invasive. And, do pose some risk to providers, like needle sticks, procedures, that kind of thing. And we don't want people to end up on a heart lung machine with a dead brain because that just creates distress for the family. So we, we try to decide who is best to resuscitate in hospital using a point of care potassium and the HOPE score. But that's a subject for another day. So going back to high level as an ALS provider, you're going to do the same. BLS stuff. We're checking for signs of life, taking note of how long the patient's been buried, and we're starting CPR. But our goal is to get an ECG monitor on there. And if we can to check the patient's temperature, then we're dividing our care based on whether it was a short burial or a long burial. If it was a short burial, great. We are going to measure that patient's temperature and we're going to bias towards terminating. Essentially, if we don't know the temperature, we're going to terminate after 20 minutes, or if it's over 30 degrees, we're going to terminate after 20 minutes. anyone whose core temperature is less than 30, they go to hospital. if it's a burial duration of greater than 60 minutes, or we don't know how long the patient was buried, then we're going to start dividing based on EKG, witness cardiac arrest, and airway patency. People who have V fib or PEA or an unknown rhythm, we divide based on temperature. A witness cardiac arrest, we divide based on temperature. PEA and a patent airway, we divide based on temperature. And these people have been buried a long time, but we don't know their temperature. We bias towards taking them to the hospital. We transport with CPR. That's the main difference in comparison to the less than 60 minutes group. And finally, if the EKG shows a systole, it was an unwitnessed arrest. The airway was obstructed with snow. We're going to terminate CPR because the likelihood of survival is low. All right. We did it. We got through the BLS and the ALS algorithms. Let's take a short musical interlude and then we'll dive back in with a couple of cases to 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 what you would do and how you would approach. This case that we're talking about. When you hear this. The sound. Think about what. You would want to know, or the actions that you would take next?

Imogen: 26:00

Case 1: Partner Avalanche Rescue

Patrick: 26:03

So you're out with a ski partner as a group of two. There's been a persistent slab problem, maybe 50 centimeters deep. In the snowpack. But the difficulty of triggering it has been increasing. Over the last few weeks. So for better for worse today, you've. Been stepping out into bigger terrain. Skiing and Alpine bowl and working. And your runs further into the bowl. On the third run. Your partner's keys first and triggers a large slab avalanche. You know, at the point last seen, but you don't see your partner and you can't. I can't hear him when the debris settles. You note the time of the. Avalanche conduct a beacon search. Locate a signal with the lowest point at 1.2 meters. Digging aggressively. Only into the debris from about 1.5 meters, downhill of your probes. Probe strike you, reach your partners face. What do you want to know? And what do you Want to do. First. Check the time note the duration of the burial. And this case, let's say He's been buried for 20 minutes. As you reach his face, your partner 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 on his back. Let's. Pause and think about where we are and the algorithm. 20 minute burial open airway. We're proceeding down the less than 60 minutes, burial. Pathway. What do you assume? Is the potential. I will cause. Of arrest. And what are your next Few actions. The presumed cause of death. If your partner looks dead, is. Uh, we'll check for signs of life for, at most. 10 seconds because he's been buried for less than 60 minutes. He has no. Signs of life, no movement, no breathing, 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. Isn't likely to do anything for our partner. Because of the time needed. For any. Help to arrive. How long should we keep resuscitating him? In general. And to be clear, this is outside. The guideline because it doesn't directly address partner rescue. I think. That 20 to 30 minutes of CPR is the most that should be attempted. There's a few reasons for this. Uh, survival after. For a longer period of CPR is very unlikely. Increasingly unlikely. And CPR quality is likely to drop off. Uh, pretty quickly with a single rescuer. It is hard work to do good CPR. We tire out. And the effort of. Doing CPR for a longer can start to compromise the safety of the rescuer. Causing exhaustion, sweating, increasing risk of hypothermia, et cetera. So those are all reasons not to continue. Longer than about 20 to 30 minutes. Of course, I'm never going to tell you that you. You shouldn't do it longer. And you'd be hard pressed to stop on. On a loved one. But this is a happy podcast. At. Least for now. So in this case, your partner starts trying to breathe. And you check for a pulse and he now has a pulse, but he remains unresponsive. where do you go from there? We're going beyond. The algorithm now, but my priorities would be these first call for help. There's no way I'm getting him out alone. We need to be careful. Careful with him and trauma remains a possibility. So do a Thorough secondary exam and make sure he's not bleeding. I'd make sure that. That is. Breathing seems adequate, you know, 10 to 12 breaths per minute. I'm not Going to have to supplement his breathing. Then I'm going to start. Protecting him because we're going to be there for a while. I want to get him off the snow onto something. Insulating cover him with layers. Hopefully not, but maybe. Think about what's going to happen. If I have to spend the night. I'd better hope help. Is coming. I'm going to reevaluate frequently and be. 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 case partner rescue. Less than 60 minutes. We assume that if our partner. is not breathing and shows no signs of life has no pulse. But the cause of death that we can potentially reverse as this fixture. And to review, we're going to check for. Signs of life for no more than 10 seconds. We're going to get five rescue breaths start. Start CPR and continuing that CPR for somewhere between 20 and 30 minutes. And if we get return of spontaneous circulation, hurrah, Our lives. Just got much more complicated. We're going to need to think about our next steps. So that's. Simple simple enough. Let's move on to case two.

Imogen: 31:01

Case 2: Professional Avalanche Rescue

31:05

You're working as a professional ski patroller at a large ski resort in the Pacific Northwest. It's early spring, the first big warm up of the year, and the sun is shining. The avalanche cycle that was occurring on the February rain crest has been quiet for more than a month, and you've been getting bored of ski cutting small windslabs. However, around 2 p. m., you receive a report of a possible avalanche in the upper bowl of the resort. The reporting party reports that a cornice fell, And caused an avalanche above a traverse and that multiple skiers and riders were below the avalanche. The radio dispatcher sends all available resources to the scene and an organized rescue begins. A hasty beacon search reveals no signals, but a witness confirms that the three victims were buried. A probe line begins searching and you arrive at the scene as the ALS lead. You can see that the cornice fall triggered a deep wet slab on the February raincrust and a large pile of big blocky debris is below. Use stage to respond to victims as they're located.

Imogen: 32:08

Critically Buried Victim 1.

Patrick: 32:12

The first probe strike happens about 20 minutes after the avalanche, and the patient is excavated and exposed at 26 minutes. You arrive to the scene with CPR ongoing. What do you want to know? This is an approximately 22 year old male snowboarder. Burial time was 26 minutes, and his airway was not blocked with snow. You slide in an esophageal temperature probe, and his body temperature is 35 degrees Celsius. CPR is ongoing. What next? CPR should continue for at least 20 minutes. After 10 minutes of CPR, ROSC is obtained. Success! You assist in post ROSC care, including trauma evaluation and packaging. But you must now turn your attention 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 CPR has already been started. What do you want to know? This is a 45 year old female skier. Burial time was 65 minutes, and her airway was occluded with snow. What next? You instruct your patrol colleagues to continue CPR. You place three lead electrodes, and during the next CPR pause, you note that the patient is in asystole. CPR resumes. So, to summarize, this patient has been buried for more than 65 minutes. has no palpable pulse, has ongoing CPR, and the underlying rhythm is asystole. What do you do? Unfortunately, this 65 minute burial with asystole, in a woman who had an occluded airway, has no hope of survival. You instruct your colleagues to cease CPR, and you explain your reasoning. But there's no time yet to debrief, Because the probe line has uncovered.

Imogen: 34:17

Critically Buried Victim 3.

34:21

You already know the information you want to know right away, so I'll give it to you. This is a 36 year old male skier wearing wet jeans and a cotton hoodie. He has been buried for 90 minutes. The team noticed a large air pocket when he was excavated, and his airway was open. He is unresponsive, has no pulse, and CPR is ongoing. What are your next actions? Now, you're no seasoned pro at this, but you do have a little laminated copy of the algorithm. So, like a boss. You hook him up to a 3 lead, and while waiting for a CPR pause, you slide in an esophageal temperature probe. At the next pulse check, he remains pulseless. He's in ventricular fibrillation. His core temperature is 29 degrees Celsius. What are your next actions? And are there any changes that you need to make to your standard cardiac arrest care for this hypothermic patient? You defibrillate him and have the team resume CPR. You inform dispatch that you need an air rotor resource to transport this patient to an ECLS capable hospital with CPR ongoing. For You have a somewhat prolonged toboggan transport ahead of you. He remains in V fib. He remains in ventricular fibrillation. This gives us a chance to talk about a few extra credit points for the care of these severely hypothermic avalanche victims. We're gonna briefly cover defibrillation, epinephrine, and what's called intermittent CPR. Ventricular fibrillation in the profoundly hypothermic patient is due to cardiac irritability from the very low temperature. Those heart cells just don't like that low, low, low temperature. So defibrillation may be unsuccessful until the patient is warmed, and excessive attempts at defibrillation can be harmful to that heart muscle. So for patients with a core temperature of less than 30 degrees Celsius, we will limit the number of defibrillation attempts to three tries until the patient is warmed. So if that patient remains in ventricular fibrillation after three attempts, We're not going to shock further, we're just going to continue CPR until we can warm up the patient. For the same reason, instead of giving multiple rounds of epinephrine like you might in a normal cardiac arrest, We should withhold epinephrine until that core temperature is greater than 30 degrees Celsius. This is because the epinephrine can increase the cardiac irritability and make it harder to terminate the ventricular fibrillation, which is itself primarily due to the very low temperature. So this patient that we're transporting 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 a prolonged transport and this patient has CPR ongoing, so what are our options there? The first and riskiest option is to try to put a patroller in the toboggan performing compressions. That doesn't work well. CPR quality is likely to be low, and there's significant risk to the patroller performing the compressions while you move, and changing patrollers in and out is tough. my hope is that in this situation you might have access to mechanical CPR. I'm talking about a Lucas type device. That device would allow compressions to continue in an ongoing manner while the patient is transported. You're only going to be able to provide breaths in an intermittent manner, maybe stopping every minute or so to provide a couple of breaths, but that's probably okay in this context because the patient is so profoundly hypothermic. Their metabolic rate is likely to be very, very low, so their oxygen consumption is going to be low. And we just want to keep circulating blood, and then intermittently exchange gases. So I'd put a Lucas device on this patient, run it essentially continuously, and have someone direct the toboggan team on the way down to make intermittent stops, provide breaths, and then resume transport. A less evidence supported strategy for patients who have a very low body temperature. And by that, I mean, even lower than this patient, less than 28 degrees Celsius is you can consider intermittent CPR if there's a risk to the team or it's not technically feasible to perform continuous CPR, you could provide two minutes of CPR and then stop CPR, transport the patient for a period of time and resume CPR. This has been reported at case study level in the literature. It's never been subjected to a randomized trial. We're never going to get that trial. This might be pertinent to a team that has a prolonged. Extrication out of the back country, and they need to focus on actually moving that patient before nightfall and risk to rescuers. And so you might do intermittent CPR, recognizing that this is definitely not ideal for the patient's resuscitation, but that patient also has a relatively low chance of survival to begin with. And so the risk to the team isn't really warranted defibrillation. Max three attempts for patient with core temp, less than 30. Okay. epinephrine, hold it until body temperature is above 30, so probably until they get to the rewarming center, and then CPR, we can use continuous CPR with a Lucas device, or you might consider intermittent CPR for the profoundly hypothermic patient. And you don't have to remember all of this because it's in the tiny text on the bottom of that algorithm. So that's it for our review of the ICAR critically buried avalanche resuscitation algorithm. I hope that the take homes you get from this are that high quality BLS care remains important for these patients and that the big changes that we make to their care hinge around the duration of burial, signs of life, evidence of an occluded airway. And then if we're performing ALS care, perhaps their core body temperature and the ability to monitor their underlying heart rhythm. In the majority of situations, we're going to be providing CPR for these patients until we can transport them to a definitive care. However, there are times in warm patients who had blocked airways where we might call it after 20 minutes of attempted resuscitation. And that's entirely appropriate. I don't think. You should be expected to be able to regurgitate this information in a stressful situation. So if you are potentially someone who would respond to a critically buried avalanche patient, if you're a member of a ski patrol or a search and rescue team, or a flight resource that does scene calls in the mountains. I would consider saving this resource to your phone or creating a card that you can keep in your pocket, because this is a low frequency, but high consequence event. And it's important that we feel good about the care that we're providing and provide evidence based care that gives the right patients the right chance of survival. That's it for this episode of wilderness medicine updates. Thank you for listening. I'll be back soon with more mountain medicine content straight to your ears. In the meantime, if you enjoy the show, the best way that you can show your support is to share the show with someone you think would enjoy it. Pass it along to another doctor, nurse, ski patroller, medical student, EMT, paramedic, SAR member, skiing buddy, family member. And if you have a moment, give the show a five star review on Apple Podcasts or Spotify. I don't make any money off this thing, I just pay money, but I'm putting in the time, putting in the 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 with comments, questions, or ideas for future shows. Best way to do that is to send me an email at wildernessmedicineupdates at gmail. com and I'll get back to you soon. Until next time, stay fit, stay focused, and have fun.