AVALANCHE

Image (1)ScanCrit is currently having a mini-symposium in Zermatt, and it includes leisure-time skiing. The conditions have been less than favourable, windy with low cloud cover and bad visibility – but also lots of fresh snow. This creates a high risk setting, as the conditions are avalanche prone – but are also very tempting for off-piste skiing. So, it was time to revisit our article on avalanches published in Journal of Royal Army Med Corps in 2016.

Off Piste and Back Country skiing
So, as we’re skiing into the backcountry we’re looking for signs of danger and safety and adjusting our skiing and group precautions accordingly. The key take-home point in the review article is that you don’t want to get caught in an avalanche. If you do get caught, the main difference is getting completely buried or not. If you get completely buried, your chance of survival is around 50%. This is mostly due to asphyxia.

Carry the right equipment and know how to use it, as in the case of an avalanche burial, the victims companions are the only real chance of getting the victim out alive.

Asphyxia and trauma
The main killer in avalanches is asphyxia, accounting for about 80% of deaths. But as you move from ligth, fine snow, to heavy wet snow – or to steeper terrain and extra terrain features like rocks and trees, death by trauma moves higher up the list. The last killer is hypothermia, but sets in later, and is more of a concern after you’ve found the avalanche victim alive and start extrication and continue transport.

jramc-2016-December-162-6-406-F1.large

This graph shows the desperate race against time if a skiing companion has gotten buried in an avalanche. Basically, it’s up to the victims friends to get him out. We have organised avalanche rescue personnel, but the sad truth is they will never get there quickly enough to save the victims life. It’s up to the rest of the group – you’re on your own. One article reports mean extriacation times by companions vs rescue teams as 16 min vs 150 mins. From the graph above, it’s easy to understand the implications. When the rescue teams arrive, you’re sadly moving towards corpse retrieval.

Searching and digging
This is were the avalanche beacons come into play. To avoid interference and false targets: Remember to tell everyone at the site to switch their beacons away from transmit! Turn them off or to search. When the victim is located with beacon, you’ll need to get the exact location with an avalanche pole. Now, dig!

But the digging is where many go wrong. The mean burial depth is 80-150cm, so if you start directly above the victim, you’ll have to dig a deep hole that gets progressively harder to shovel snow out of. You’ll also be standing on the victim, and extrication will be difficult. So, do the slightly couter-intuitive thing, and start just downhill of the victim and dig towards the victim, and let extra diggers stand in an inverted V-shaped conveyor belt on both sides of the main digger, and help clear away the snow shoveled out by the main digger. Rotate on being the main digger. This has been shown to be the most effective digging method.

Transportation and medical treatment
If the victim is alive when dug out, the main concern is hypothermia. While you’ll want to check for any big trauma, this is not the time to remove clothing or spend a long time up in the snow. To minimise continued temperature loss, the patient will stay in the wet clothes, but be wrapped in something vapour tight, like a space blanket or bubble wrap, and then add an isolation layer outside this again, like blankets, sleeping bag etc. The patient must be monitored for a new fall in temperature as blood flow returns to the cold superficial tissues and extremities. As temperatures go lower, the risk of cardiac arrhythmias and cardiac arrest increases. See figure in the review article on avalanches.

Hot tip: Don’t get caught
Like most medical litterature, the focus is on traetment and not prevention. Medical articles on avalanches are on people recovered from avalanche burials. It’s grim reading. But the best approach is to not get caught in an avalanche in the first place. While back country winter activities in steep trrain will always carry a risk that must be accepted by the participants, you should go to lengths to minimise these risks.

For Europe, check out Avalanches.org, or for the US: Avalanche.org

Also follow the articles and discussions on places like the backcountry skiing site WildSnow

The Prehospital Management of Avalanche Victims, J R Army Med Corps, 2016.

Body Positioning of Buried Avalanche Victims, Wilderness Environ Med, 2016.

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