Winter outdoor recreational activities in wilderness environments or remote locations are a popular pastime. As such, various snow-related incidents and injuries may occur and present potential challenges. Awareness of the possible dangers and being well prepared, such as having the proper equipment, may maximize safety and minimize injuries, particularly in areas where resources may be limited.

The image shows an avalanche in Zinal, Switzerland.

Image courtesy of Wikimedia Commons/dahu1. Icons courtesy of Dreamstime/Alex Andreev.

Avalanches

Avalanches, or snow slides, are the rapid flow of snow down a hill or mountainside.^[1] They can occur in any terrain that is good for skiing or other winter activities (eg, snowmobiling, snowshoeing); in 90% of cases, avalanches are triggered by the victim(s) or a member of the victim's group.^[1] These incidents can be deadly; according to the National Avalanche Center, avalanches kill more people on national forests than any other natural hazard.^[2] Worldwide, more than 150 people are killed annually in snow slides.^[1]

Avalanche preparations

There are commercial products that may increase the likelihood of survival if one is caught in an avalanche. Required equipment for traveling in avalanche terrain includes the following^[3,4]:

• Transceiver – Transceivers act as a beacon to help others to locate avalanche victims.
• Probe poles – Collapsible probes are easier to use than improvised probes for locating buried victims.
• Shovel – A good pack shovel is essential for digging in an avalanche. The snow may be packed so hard after a snow slide that other methods are ineffective.

These items, especially the transceiver, take practice to use correctly and precisely.

Note: Having the proper equipment is no substitute for experience, and it should not lead to acceptance of an increased avalanche risk.

Image of avalanche security, search, and rescue equipment courtesy of Wikimedia Commons/Nolispanmo.

Monitoring

Components of an avalanche include a starting zone, track, and runout zone.^[4,5] An avalanche releases at the starting zone, and debris typically comes to rest at the runout (or deposition) zone. The track is the section of an avalanche path that lies between the starting and runout zones.^[4,5]

The two primary types of avalanches are point releases ("sluffs") and slabs.^[4,6] A point release avalanche occurs when the uppermost layer of snow slides; this involves small amounts of near-surface snow that releases at a point and fans out as it descends. A slab avalanche occurs when a sheet of weak snow breaks loose from the underlying layers and slides downhill; this can involve very large amounts of snow.^[4,6]

The science of avalanche prediction involves an understanding of the terrain and analysis of the snow pack.^[4] There are multiple ways to evaluate snow stability, including digging a pit into the snow.

Image courtesy of Science Source/William D Bachman.

Three factors—slope, snowpack, and trigger—are required for an avalanche to occur.^[1,6]

Avalanches most commonly occur above tree lines, as well as on north- to east-facing slopes,^[4] typically on slopes that are steeper than 30-35 degrees.^[1,6]

Signs of an unstable snowpack include recent snow slides, shooting cracks, and a "whumping" sound.^[1,6] The risk of a snow slide is greatest immediately following a snow storm, with up to 80% of avalanches occurring during or immediately after such a storm. The larger the amount of snowfall, the higher the risk for a significant avalanche.

As noted earlier, the majority of avalanches are triggered by avalanche victim(s) or members of their party.^[1] New snow and wind are also common triggers.^[1,6]

Image courtesy of Sam Shlomo Spaeth.

Avalanche safety and recovery

Essential precautions to take when traveling in an area with a risk of avalanche include the following^[4]:

• Always travel with at least one other person.
• Ensure all transceivers are on, working, and set to transmit.
• Tighten any loose clothing and light day pack straps, close zippers, and secure hats/helmets and goggles.
• Ensure the ability to easily jettison any heavy packs, ski poles, and skis in the event of a snow slide.
• Cross through low-risk areas, such as the tops of ridges and areas of heavy timber and large terrain features. Only one person should cross at a time. Have a preplanned escape route.

In the event of an avalanche, remember the following^[7]:

• Always attempt to escape to the side of a snow slide; never try to outrun an avalanche downhill.
• Jettison heavy packs, snowboards, skis, and ski poles, if possible.
• Attempt to create an air pocket; cover the face with hands, grab the collar or pack straps, or cross arms in front of the face.
• If on a snowmobile, try to stay on the machine.

Once the snow stops moving, the ability to move is typically nil or grossly restricted.

Image of a person training with an avalanche transceiver (left) and a close-up of a transceiver (right), respectively, courtesy of Flickr/Richard Allaway and Wikimedia Commons/Nolispanmo.

Avalanche survival factors

Approximately 75% of buried victims die from asphyxia; most of the remainder die from major trauma, and a few die from hypothermia.^[4]

Time (duration of burial) and an air pocket are the most important factors for victim survival in avalanches.^[4]

Individuals with an air pocket who are found within 15 minutes or less have about a 95% survival rate; survival drops to 69% in the absence of an air pocket.^[8]

After 30 minutes, the odds of finding a live victim decreases significantly.^[4] The likelihood of survival is also reduced in victims buried deeper than 7 feet, as well as those buried face down, because the air pocket decreases as the snow melts. However, if a victim has any type of structure that provides an air pocket, they can be recovered alive even after being buried for 24 hours or longer.^[4]

The photograph shows a ski patroller looking down a 2,000 foot avalanche path.

Image courtesy of Will Smith, MD, FAWN, Paramedic.

Because most avalanches take place far from professional rescuers, other members of a group are the best chance of recovery for a buried victim, particularly if the victim was wearing a transceiver. Always, if possible, first ensure that there is not an ongoing risk of avalanche in the slide zone.

If the victim was wearing a transceiver, rescuers should proceed as follows^[4]:

• Turn their transceivers to receive.
• Go to the point that the missing person was last seen, and mark it.
• Conduct a quick search, looking for partially buried victims or clothing.
• Use transceivers to find the victim.

If the victim was not wearing a transceiver, then rescuers should perform the following^[4]:

• Go to the point that the missing person was last seen, and mark it.
• Conduct a quick search, looking for partially buried victims or clothing.
• Probe for the victim in likely spots, such as in front of large terrain features or trees, bends in the snow path, and in the runout area.
• Keep in mind that most victims will not survive being buried deeper than 7 feet. Thus, shallow probing of more areas is better than deep probing of a few.
• An organized probe line, in which rescuers line up to probe the snowpack, is most useful for body recovery.

The image is a graphic view of avalanche rescue patterns using an avalanche transceiver on Mount Vardousia in Greece

Image courtesy of Wikimedia Commons/K Gkofas.

Once a buried victim is found, use probes to determine the depth and orientation.^[4]

The first priority should be to expose the victim's airway.^[4] Avoid standing over the victim, as this may decrease their air pocket.

Dig downslope of the victim's location, taking care to avoid injuring them with the shovel blades.^[4]

Once victims are recovered from the snow, focus on rewarming them and maintaining their airway.^[4]

Image of an avalanche rescue in progress courtesy of University of Exeter via Flickr.

Indications for cardiopulmonary resuscitation (CPR)

Avalanche victims who appear to have suffered death from asphyxiation or hypothermia should receive CPR.^[4,9]

People buried for a short duration who appear to have snow in their airway and have no air pocket, and who appear to be in cardiac arrest should receive CPR and airway management. Ceasing efforts may be clinically indicated in the field.^[9]

Individuals most likely to have suffered hypothermic cardiac arrest, have an obvious air pocket around them, are without signs of trauma, and have a core temperature lower than 30°C (86°F) should receive CPR.^[4] Special consideration should also be taken for hypothermia treatment.

CPR should not be administered to patients with obvious life-threatening trauma.

The image depicts an elderly man with severe hypothermia (23°C [73.4°F]) undergoing rewarming with a surface cooling device.

Image courtesy of Roser M, Martens F, Storm C. ISRN Cardiol. 2011;2011:617912. [Open access.] PMID: 22347647, PMCID: PMC3262521.

Ski and Snowboard Injuries

Trauma to the head, knees, shoulders, and wrists are common ski and snowboard injuries.^[4,7]

Head injuries

The risk of trauma to the head from skiing and/or snowboarding increases with high speeds and jumping.^[4,7] Head injuries range from mild concussion without loss of consciousness to severe open skull fracture. Use of a helmet may minimize or prevent head trauma.^[4,7]

The diagrams illustrate the forces on the brain in concussions (left) and coup-contrecoup injuries (right).

Images courtesy of Wikimedia Commons/Patrick J Lynch.

Management of head injuries begins with an evaluation of the patient's level of consciousness, protection of their airway, and/or providing respiratory assistance, as needed.^[4,7] For those with severe head injury, also immobilize the cervical spine.

For individuals with mild head injury, monitor them for at least 6 hours.^[4,7] Emergent medical evaluation is required for those with worsening headache, vomiting, and/or changes in alertness during that period.

Emergent medical evaluation is also required for even minor appearing head injury(ies) for anyone taking blood thinners, those who have bleeding disorders, and/or persons older than 65 years.^[4,7]

Image of a trauma patient courtesy of RafahKid Kid via Flickr.

Concussion

A concussion is a specific type of head injury that results from trauma, regardless of whether loss of consciousness occurs.^[7,10] Signs/symptoms include a loss of balance, headache, nausea, and difficulty concentrating.^[11]

It is crucial that anyone with a concussion see a primary care provider before they return to normal activities or sports.^[7]

Image courtesy of Wikimedia Commons/Mandrews12.

Knee injuries

Trauma to the knee in skiers and snowboarders may range from a stretching of a ligament around the knee joint to multiple ligament tears that result in instability of the knee joint. The injuries often occur as the body twists around a stationary foot, with falling backward, or with a direct impact to the knee joint.

Although common and painful, a patella dislocation (left) is typically not a serious injury. However, a knee joint dislocation (right) is a true emergency and requires medical evaluation, observation, and treatment.^[7]

Any injury that results in loss of pulse or sensation in the foot is a true time-dependent emergency.

Patella dislocations are treated by having an assistant straighten the patient's leg and simultaneously pushing the patella back to the middle of the knee.^[7] Then, the knee should be splinted so that it cannot bend until cleared by a clinician.

Images courtesy of Wikimedia Commons/James Heilman, MD (left) and Medscape (right).

These images are from a patient with a skiing knee injury that was managed conservatively.

Left: The initial plain lateral radiograph of the right knee does not reveal any obvious bony injury.

Center: The sagittal T1-weighted sequence magnetic resonance image (MRI) demonstrates extensive bone marrow edema within the lateral tibial plateau extending to the articular cartilage.

Right: The coronal short TI inversion recovery (STIR) sequence MRI also shows extensive bone marrow edema within the lateral tibial plateau, with extension to the articular cartilage.

Images courtesy of O'Donnell ME, Badger SA, Campbell D, Loan W, Sinnott B. J Med Case Rep. 2007;1:11. [Open access.] PMID: 17448236, PMCID: PMC1865549.

Conservative treatment for a knee injury includes splinting the knee in a straight leg position. Many commercial and improvised splints and braces are available to provide support around the knee and prevent it from bending or sliding left or right; most often this requires a splint or brace that spans the length of the leg.

Crutches are usually necessary because weight bearing on the injured knee frequently causes pain.

The images show examples of conservative treatment in acute primary patella dislocation with a brace (A), posterior splint (B), and cylinder cast (C).

Images courtesy of van Gemert JP, de Vree LM, Hessels RA, Gaakeer MI. Int J Emerg Med. 2012;5(1):45. [Open access.] PMID: 23273401, PMCID: PMC3545847.

Shoulder injuries

Fractures of the clavicle, humerus, and scapula often result from skiers and snowboarders landing directly on their shoulder(s).

Rotator cuff muscle tears and shoulder dislocations often result from falling onto an outstretched arm.^[7]

A prior shoulder dislocation makes a repeat dislocation more likely to occur, but it is also easier to reduce.^[7]

The radiograph on the left reveals fractures of the clavicle and scapula. The three-dimensional (3-D) computed tomography (CT) scan reconstruction on the right demonstrates right-sided scapular and rib fractures in a different patient.

Images courtesy of Wikimedia Commons/James Heilman, MD.

In general, shoulder injuries are managed with a sling and swath splinting technique. The sling supports the arm, and the swath keeps it close to the body.

Any shoulder injury that results in a loss of a pulse at the wrist or the presence of numbness or weakness in the hand is a true emergency.

The images were obtained in a patient who suffered a pulmonary contusion and left scapular body fracture, as well as had pulselessness of the left arm. Despite emergency vascular intervention, complete palsy of the left arm resulted. The scapular fracture received conservative management. Despite further neurosurgical treatment, the patient was eventually lost to follow-up.

The CT scan on the left demonstrates extravasation of contrast agent in the left subclavian artery, indicating a rupture. The 3-D CT reconstruction of the shoulder girdle on the right shows displacement of the left scapula as well as extravasation of the contrast agent and the missing presentment of the ipsilateral subclavian artery.

Images courtesy of Krasnici S, Schmidt J, Reimann K, Ertel W, Topp T. Patient Saf Surg. 2013;7(1):24. [Open access.] PMID: 23830143, PMCID: PMC3717289.

If a patient has had multiple shoulder dislocations previously and they are certain the present injury is another shoulder dislocation, it is reasonable for a trained healthcare provider to reduce the dislocation—after an appropriate examination—without obtaining x-rays.^[7]

The sooner a reduction is attempted, the more likely it is to be successful.^[7] Although many different techniques to reduce shoulder dislocations exist, all share slow, persistent traction to enable the humeral head to slide back into place.^[4]

Anterior images of shoulder dislocations courtesy of Wikimedia Commons/Hellerhoff.

Wrist injuries

Skiers and snowboarders may suffer wrist injuries, commonly as a result of falling onto an outstretched hand.^[7] The injuries may range from stretching of the associated ligaments to fractures and dislocations of the hand and arm bones.

Wrist injuries are generally treated with a splint that spans from the base of the fingers to the elbow.^[7] Commercial and improvised splints can be effective as long as the splint supports the wrist joint and prevents it from moving.

For situations in which a clear deformity is present, splint the wrist in the position in which it is found.^[7]

Injuries resulting in loss of pulse at the wrist, weakness or numbness in the hand, and/or open fractures require immediate medical attention.^[7]

The anteroposterior radiographs depict fractures of the right and left distal radius and scaphoid.

Images courtesy of Ozkan K, Ugutmen E, Unay K, Poyanli O, Guven M, Eren A. J Med Case Rep. 2008;2:93. [Open access.] PMID: 18373872, PMCID: PMC2292201.