Ep. 21 - Snow Immersion Suffocation

In this episode, we dive into one of the most overlooked but deadly hazards in deep powder skiing: snow immersion suffocation (NARSID). Unlike avalanches, snow immersion deaths happen silently—often within feet of a groomed run—when skiers and snowboarders fall into deep snow or tree wells and become trapped. We explore the research behind these incidents, where and how they occur, who is most at risk, and the tragic mechanics of asphyxiation in deep snow. Using studies from Van Tilburg, Baugher, and Cadman, we break down ra eal survival story, discuss prevention strategies, and how both bystanders and professional rescuers should respond. Whether you’re a backcountry adventurer, resort skier, or ski patroller, this episode will change the way you think about deep snow safety. Stay aware, ski with a partner, and stay out of tree wells.

Must Watch: GoPro Awards: Tree Well Rescue

Citations

Baugher, P. (2006). Risk trends at U.S. and British Columbia ski areas: An evaluation of the risk of snow immersion versus avalanche burials. In Proceedings of the 2006 International Snow Science Workshop (pp. 584–591). International Snow Science Workshop.
URL: https://arc.lib.montana.edu/snow-science/item/2076

Cadman, R. (1999). Eight nonavalanche snow-immersion deaths: A 6-year series from British Columbia ski areas. The Physician and Sportsmedicine, 27(13), 31–43.
URL: (No publicly available link found—may be available through institutional access)

Van Tilburg, C. (2010). Non–avalanche-related snow immersion deaths: Tree well and deep snow immersion asphyxiation. Wilderness & Environmental Medicine, 21(3), 257–261.
URL: https://doi.org/10.1016/j.wem.2010.04.004

Van Tilburg, C. S., Grissom, C. K., Zafren, K., McIntosh, S. E., Radwin, M. I., Paal, P., et al. (2017). Wilderness Medical Society practice guidelines for the prevention and management of avalanche and non-avalanche snow burial accidents. Wilderness & Environmental Medicine, 28(1), 23–42.
URL: https://doi.org/10.1016/j.wem.2016.10.001

Chapters
00:00 Introduction: The Hidden Dangers of Snow Immersion
00:37 Understanding Snow Immersion Suffocation
02:58 Historical Context and Research
03:09 Where and How Snow Immersion Happens
04:54 Mechanics of Snow Immersion Traps
06:23 Risk Factors and Victim Profiles
09:27 Prevention and Safety Measures
11:48 Rescue Techniques and Immediate Response
13:34 Professional Rescuer Guidelines
16:12 Advanced Medical Care and Resuscitation
20:11 Conclusion and Final Thoughts

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

Connect with us by email at wildernessmedicineupdates@gmail.com.

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

Transcript

0:05

Imagine you're skiing or snowboarding in a beautiful backcountry glade. The powder is waist deep. The trees are towering above, and each turn is effortless. It's a perfect day, but in a split second, your world flips. Literally. You fall tumbling forward into a tree. Well, that powder you're enjoying collapses around you like quicksand. Your arms are pinned and your mouth is filling with snow. You try to yell for help, but there's no air. You struggle, but every movement makes you sink deeper into the hole. This is snow immersion suffocation, one of the least studied but most lethal hazards in powder skiing. Unlike avalanches where the destructive force is obvious, this danger lurks silently beneath the surface, waiting for an unsuspecting skier or rider to fall the wrong way. Welcome back to Wilderness Medicine, updates the show for providers at the edges. I'm your host, Dr. Patrick Fink, and today we're going to explore the history of snow immersion research, the realities of how it happens, and importantly, what you can potentially do to avoid this scenario. And some guidance for care providers who may manage patients who are victims of snow immersion. So what is snow immersion? Snow immersion suffocation sometimes called non avalanche related Snow Immersion death, or N-A-R-S-I-D for not easy, but short happens when a skier or snowboarder falls into deep snow and becomes unable to escape leading to asphyxiation. Most often this occurs in a tree. Well, and this is the void that forms around the base, particularly of large conifer trees where the snowfall is not compacted and where there's perhaps a void of, um, space where branches along the base of the tree create an area where you can fall in. But it can also happen along deep drifts in gullies or in other sorts of micro terrain traps. Unlike avalanches, which get a lot of attention, snow immersion deaths are relatively quiet and are only recognized within the local community. I'm bringing this to attention in the podcast because you know our community here in Bend, Oregon Mount Bachelor is actually one of the hotspots, if you will, of snow immersion suffocation. We with the Cascade Snowpack, which we'll talk about in a minute. See a lot of these problems and just recently suffered another snow immersion suffocation death at the ski resort. These deaths can occur within feet of a groom ski trail. A victim disappears often without a sound and their fate is sealed in minutes unless someone sees it happen and acts immediately. This wasn't always recognized as a major risk in ski areas, and it took a series of incidents and dedicated research to expose just how deadly deep snow could be. So where does deep snow immersion happen? For snow immersion to be deadly, you need three things. First, you need deep and unconsolidated snow, often a meter or more of fresh powder. Two, you need some steep or tree terrain areas with tree wells or terrain traps that can increase the risk associated with that snow. And third, you need a rider falling headfirst. Most fatalities occur when someone goes into one of these tree wells upside down. This combination is most common in Western North America. British Columbia, Washington, Oregon, California, and Colorado are hotspots because they have heavy snowfall and dense evergreen forests. Any studies that I mention during this podcast, check'em out. Down in the show notes, I have'em listed in order and you can see these references if you like. Studies by Bauer from 2006 and Van Tilburg in 2010 confirm that the majority of documented snow immersion deaths have occurred in the Pacific Northwest and in the Sierra Nevada. Unlike avalanche terrain, which is often remote, high altitude terrain, snow immersion deaths typically happen in bounds, even on well-traveled slopes, and this is probably a fact that relates to the fact that the majority of skiers are in those settings. We would see more of these events in the back country if we had an equal skier population there. There's nothing specific to the ski resort that makes this more likely to happen there. It's simple exposure, most likely. Indeed Ski patrollers in places like Mount Bachelor, Whistler, and Jackson Hole have reported multiple fatalities within sight of a lift or a groomed run. Why does that happen? To understand that we're gonna need to look at the mechanics of how people get trapped. A skier or snowboarder enters an area of deep P, often weaving between trees. They catch an edge, hit a hidden stump, or simply lose their balance, and suddenly they're falling forward. Tree wells are the most dangerous type of trap because a conifers branches deflect snow away from their base, forming a deep soft cavity around the trunk. If a rider falls into one head first. That can kind of act like a sinkhole. And the more that that rider struggles, the deeper they sink into the hole, and the more the snow around them falls in around them and seals them in. In a 1999 study by Cadman from British Columbia, researchers simulated falls into tree wells. They found that even experienced skiers and snowboarders were unable to self rescue. In most cases, the snow would lock in around the patient's body preventing movement, and in a panic, victims thrash compacting the snow further and worsening their entrapment. Bower in 2006 had a study that reinforced these findings. Over 90% of snow immersion fatalities occur when the patient is upside down. Two reasons there. First, more likely to involve the airway because you're face down in the snow. And second, even a small amount of snow covering the face in that setting can lead to suffocation within minutes. So who's at risk of this? Snow immersion doesn't just happen to beginners or reckless skiers. It often happens to advance skiers in deep powder conditions. Research shows that about 85% of victims are male, and typically between the ages of 18 to 35, and that comes from Van Berg's 2010 paper. Most are experienced skiers or snowboarders riding off piece, so off the groomed run in deep powder. This has gone back and forth between studies, but generally speaking, there are slightly more snowboarders than skiers involved in snow immersion deaths, and that has been hypothesized to be related to the difficulty of detaching from their snowboard while inverted. But that study where they simulated tree well immersion didn't show any benefit to being able to escape from your skis. So I suspect that this is more likely related to how snowboarders fall. Namely, if they catch a. Uh, downhill edge. They're likely to fall head first, where skiers are more likely to sort of fall in a diagonal manner, but that's just my hypothesis. Most victims, however, were skiing alone or had become separated from their groove. So the risk profiles pretty clear. If you like powder skiing and tree skiing, you need to be aware of this danger, and you probably shouldn't ski it alone. Now, once this happens, how do people die from snow immersion? The cause of death in snow immersion is asphyxiation, and that often happens within five to 10 minutes of burial, and there's two mechanisms that are proposed. The first and the most likely is airway obstruction. Specifically, you fall headfirst into a tree. Well, as a victim, your mouth and nose become packed with snow, and you can suffocate within minutes because you can't breathe. The other thing that can happen if a lot of snow packs in around you is positional asphyxia. And what that means is that in this head down position with compression on your chest, it may be harder to breathe. And so you can't actually take a breath because you've been packed in snow. Notably, unlike avalanche burials where victims may survive with an air pocket, snow immersion leaves almost no chance for prolonged survival. In Van Berg's review, all documented cases resulted in death unless rescue occurred within 10 minutes. And that's probably because when people fall in the snowfalls in around them. And so the prevalence of an air pocket is very, very low. Has anyone ever survived? Yes, but only with immediate help. So Van Berger and Bauer, both documented cases where. Rapid partner rescue saved lives. For example, one notable example involved an off-duty ski patroller who fell into a tree well, but was found by his partner within several minutes. CPR was started immediately, and he was successfully resuscitated after a few days, stay in the hospital. But these cases are rare because if no one sees the fall, the chances of survival approach zero. So knowing that, how can we stay safe? The answer looks to be prevention. So snow immersion deaths are completely preventable. Don't go skiing, I'm kidding. We know that that's not an option. So more importantly, ski or ride with a partner and maintain visual contact. So if you lose sight of one another, stop and regroup. And if one of you falls into a tree, well the other may see it and be able to initiate an immediate partner Rescue. The second is to give trees a wide berth. If you treat a tree well like a cliff, then you're less likely to fall into it. Assume the tree well is dangerous. Assume it's an edge that you don't want to go over. The third is kind of obvious. If you can stroke one. Third, staying on your feet is important. If you feel yourself falling, you want to avoid going headfirst into a tree, well, so grab the tree fall or roll towards your side and spread out your limbs to avoid going in headfirst. It is helpful to carry a whistle or a radio somewhere near your face. There was a documented case of survival in which a patient was able to call a friend using a radio when they became headfirst upside down in a tree. Well, so having a whistle or a radio some way to call for help that is near your head and that you would be able to reach in a pinch may be a prudent idea. It is also a reasonable idea to wear an avalanche beacon when skiing powder in bounds. Though this isn't standard practice, there have been plenty of examples of inbounds avalanches, and I think that it's a reasonable idea and some victims have been located more quickly after tree well burial while wearing a beacon. So these simple steps, particularly not riding alone, can mean the difference between life and death. If you need a very, very salient example of this, take a look down in the show notes and look at the GoPro video that shows a tree well immersion in real time. You can see that rescue happen over the course of just a few minutes and feel the tension and feel the urgency and understand why this would not be a good thing to continue for 20 or 30 minutes. So. What happens if you're that partner and you need to affect the rescue? If your partner goes into a tree, well, you should go directly to where they fell and you should not leave to go get help. Reason being, it may be very difficult to find that person from even a short distance away. Additionally, you may have only a few minutes to clear their airway before they die, so you need to be the rescuer. It is generally a good idea to approach from the downhill side so that you're not kicking additional snow into that tree well, and you want to dig towards their face and target clearing their airway first, and then continue digging to extricate their torso and legs. That patient needs to come out of that hole because we obviously can't work on them in the hole. And once extricated, if they're unresponsive and don't have breathing and a pulse, then you should begin CPR immediately with a presumed cause of death of asphyxia. A small point of fact here is that if this is a deep powder scenario, then you're gonna want to create some sort of little platform for you to be able to perform effective compressions. Recently the case at Matt Bachelor, a bystander began performing CPR and it was actually occurring on a snowboard that they placed under the patient's torso, which is genius. Well done. Use your snowboard, use your skis. Create some kind of platform so your compressions are actually being transmitted to the patient, and make sure to give rescue breaths. In this scenario, this is not the time for compression only CPR, because with asphyxia we need some air moving in and out to resuscitate this patient. Now, how about professional rescuers and medical management of folks after you respond to them in a professional setting? So when ski patrollers search and rescue teams or emergency medical providers respond to a snow immersion accident, the approach here is gonna be very different from an avalanche burial. While avalanche rescues often involve transceivers, probes, and large scale search operations, snow immersion rescues require an immediate focus. On location, airway management and rapid extrication. So what does the research say about how professional rescuers should handle these cases? The Wilderness Medicine Society Guidelines for Avalanche and Non Avalanche Snow Burial, also by Van Tilburg, but from 2017 provide evidence-based recommendations for professional rescue teams responding to non avalanche related snow immersion deaths. The NAR Sid we talked about earlier. These guidelines emphasize that a rapid response is critical because the chances of survival drop after that first five to 10 minutes. So if a skier snowboarder is reported missing in deep snow conditions, search teams should prioritize looking in tree wells, terrain depressions, and beginning at an area where the victim was last seen. Unlike avalanche burials where beacons, recco, reflectors, or probe lines are effective, most no immersion victims are found. With a partially visible piece of clothing or a board or what have you. So that means a visual scan of likely terrain features should be the priority, not necessarily a transceiver search, which should be kind of a secondary consideration as more resources arrive on scene. Once a patient is found, the rescue priorities are pretty clear, so we need immediate airway access and clearance heading for the victim's face, and ensuring the airway is free of snow. Before attempting to extricate the rest of the body while doing that, we wanna minimize further entrapment. So instead of pulling on limbs, we should dig from the side or from below to prevent additional snow collapsing around that airway. And then we need a rapid but controlled extrication. So unlike an avalanche victim where spinal injuries are a concern, snow immersion victims should be dug out as quickly as humanly possible, prioritizing airway and clearing that torso. And we can be less careful about those spinal precautions. Obviously, use your judgment here because this patient could have collided with the tree. So if there's evidence of trauma, take that into consideration. But those traumatic injuries don't matter terribly much if the patient doesn't survive their asphyxia. So these principles mirror the approach taken in your drowning accidents, and the goal is to restore breathing as soon as possible. When it comes to the advanced medical care for these patients, we can consider a few points. So airway management, patients who are unconscious but still breathing should receive supplemental oxygen and need to be monitored for things such as aspiration down the line. If they're not breathing, then we just wanna deliver high flow oxygen and deliver those breaths by whatever means is necessary. Take a look back at a recent episode on LMAs. That's an entirely reasonable thing. Use bag, valve mask, whatever you have available to you for pulseless victims. If there's no pulse present, then chest compressions and rescue breathing is essential because death is primarily due to oxygen deprivation. We need some gas exchange and we need to circulate that blood. How about hypothermia? Well, unlike avalanche burials, deep hypothermia is usually not a major factor in snow immersion cases because victims suffocate generally before they can cool significantly. This does in large part mirror avalanche burials in that hypothermia makes up at most one to 2% of cases. So we don't generally need to apply a hypothermic cardiac arrest protocol, namely prolonged resuscitative efforts. To these patients. What I would say and what I'll tell my teams is if you extract that patient and they're in cardiac arrest, we're gonna continue resuscitative efforts until you can get to a reasonable place where you feel like you've done a good job coding that patient. Probably 20 to 30 minutes of CPR and good respirations, and then I would prefer to obtain a core temperature and demonstrate that they're not severely hypothermic. And the chances are they're not going to be. So according to the WMS guidelines, as you're conducting that resuscitation, if there is an a ED available, we want to analyze the rhythm. And if they're in V-fib, consider defibrillating. However, the majority of these patients are gonna present in asystole because of their asphyxia. So the a ED is less likely to be helpful here than in a typical medical cardiac arrest patient. According to the WMS guidelines, if a snow immersion victim is pulseless and has been buried for over 60 minutes and has no signs of life, the likelihood of survival is extremely low. So long duration, CPR is gonna be less effective. But of course, the decision to stop resuscitation should be made based on downtime, clinical judgment, and core temperature if available. So takeaways for rescuers. If you're responding to a snow immersion incident, you need to respond quickly and aggressively with as many human resources as possible. Because we have only a short period of time before asphyxia results in death, we need all of those people to conduct a rapid visual search beginning where the victim was last seen. Most of these victims are partially visible, so we're scanning tree wells and deep snow depressions before we go to probes and transceivers as kind of a second line. Once located, our priority is to clear the airway first. Don't make it worse by compressing snow in around the patient's head and then rapidly extricate the patient to where they can be resuscitated if needed. If they're unconscious and not breathing, don't have a pulse. We're gonna start CPR and provide oxygen as soon as possible. Hypothermic prolonged CPR protocols are unlikely to be helpful, so we're gonna work them for 20 to 30 minutes with standard A CLS care. If someone survives a tree, well accident, even if they are awake and talking, they should be transported for medical evaluation because they could develop respiratory complications down the line, such as aspiration pneumonia. So let's wrap this up. Snow immersion suffocation is one of the silent but deadly hazards in the winter environment. The difference between life and death in these scenarios often comes down to minutes and. To the actions of nearby skiers and rescuers by understanding how these incidents happen, skiing with a partner and knowing how to respond. If we see someone fall into a tree, well, if we're responding to one of these events, can turn the tide on this killer entity. So ski safe, stay with a partner. And treat tree wells like cliffs and be aware that the majority of these events happen after several feet of fresh snow and are more prevalent within the Western us. Whether you're a backcountry skier, resort skier, ski patroller, or SA a member, I hope this episode. It helps parse the way that you think about deep snow safety and how you respond to these events. So please stay aware, ski with a Partner, and avoid trade wells. That wraps up this episode of Wilderness Medicine Updates. I hope you enjoy the show. If you want to get in touch, as always, you can reach out at Wilderness Medicine updates@gmail.com. I appreciate all the questions that I get there and have some really interesting things coming down the pipeline because of connections that have been made through that outlet. So not yet on any social media platforms, prefer to meet one-on-one with folks. No question is a stupid question.'cause if you have the question, then somebody else does and I love to hear from you all. Even if you just wanna shout out and say, hey. If you like the show and want to help support me, the best way that you can do that is two things. The first is give me a five star review on Apple Podcasts on Spotify, wherever you listen.'cause that helps get that out to more people. And then the second thing that you can do is you can share this episode or an episode that you like with someone like you, whether that's a ski patroller, a backcountry skier. Someone in your wilderness first aid class, an EMT, A doc, a nurse, a flight medic, member of your military crew, whomever you think will appreciate this, share it with one person today and help this show grow and reach more people. I thank you for doing that. It's the best way and each one of these episodes we're seeing a little bit more traction. Get more traction, and I love that because. I wanna bring good information to more people, more people just like you. So I hope that you enjoyed this episode. I'm your host, Patrick Fink, and until next time, stay fit, stay focused, and have fun.