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Cold - The tricks

1. Spotting risk factors

With good clothing, cold injury should not be a major concern in normal conditions, but there are a number of factors which can significantly increase the risk of cold injury. Being aware of these factors is an important aspect of good group management. The factors divide into two groups: environmental and individual.

The environmental factors are:

Air temperature: the colder it is, the greater the rate of heat loss. This is the first factor to consider.
Wind: wind increases the rate at which your body loses heat through convection. The stronger the wind, the greater the cooling effect or “wind chill”. Roughly speaking, every 5 km per hour of wind reduces the temperature by 1 oC.

Damp: a damp body loses heat through much faster than a dry body, especially in windy conditions. Wet cold wet weather is much more dangerous than dry. Excessive sweating into non-wicking fabrics also presents a risk since the body will cool faster. As the diagram shows, the wind-chill effect can be considerable even on quite moderate days. To be warm you must be dry and sheltered from the wind!

Cold water immersion: through falling into a river or breaking through the ice into a lake presents an extreme risk since the body loses heat very rapidly through convection.

The individual factors are:

Inactivity: exercise generates heat. Stopping after a period of exercise (on a summit, at a rest stop, or at a climbing belay) will make you much colder. The situation can be made worse if the earlier exercise has caused sweating leaving you damp.
Hunger, thirst and fatigue: make it harder for the body to produce heat needed to keep you going in the first place. Hypothermia can set in later in the day when tiredness, dehydration and lack of food reduce the body’s defences, sometimes to dangerously low levels.
Sex and physique: body fat (as well as being a store of energy) acts to insulate the body against heat loss. Skinny people will get cold faster than heavier people. Women tend to be more resistant to cold than men. Equally, children or small adults will be more susceptible to the risks of cold injury since small bodies have a proportionately greater surface area and so tend to lose heat faster.
Poor or inadequate clothing: your clothing works just like the lagging on a hot water tank. It insulates the body and reduces the rate of heat loss. Good modern clothing is one the most crucial defences against the risks of cold injury.
Illness or injury: can reduce the body’s ability to resist the effects of cold. Injury combined with inactivity is the reasons why hypothermia can be such a significant factor in other accidents (such as falls) where the victim survives the initial accident only to succumb later to the effects of cold.

2. Improvising shelter – using a group shelter

When conditions are very bad, or if the group is gong to be inactive for a period of time (perhaps looking after an accident victim), you may need to take shelter. Taking shelter is all about reducing the risk of cold injury by removing the environmental factors (cold, wind, and damp). A group shelter is a brilliant device to carry since it can be set up in seconds and provides an amazing amount of protection.

Using a group shelter is straightforward:

Everyone removes skis and packs.

The group (two, four, six or more people depending on the size of the shelter) all stand in a tight circle facing inwards.

Pull the group shelter over the heads of the group with the bottom dangling down towards the ground.

At the same time, everyone kneels down sealing the bottom of the shelter against the base of the snow.

It can be a tight fit inside a group shelter but – especially in windy or stormy weather - it will feel amazing warm and beautifully quiet to be out of the wind. In bad conditions, the group shelter can provide an oasis of calm to take a break for some food, wait for slower members of the group, take time to plan a safe route out, or simply use the opportunity to make a go/no go decision in (relatively!) relaxed surroundings.

3. Getting shelter – building a snow cave

For longer term shelter - if you are unfortunate enough to get stuck out overnight, or if a big storm comes in and you need to take shelter for a few hours - your best option is to dig a snow-hole or snow-cave. Digging a snow cave is quite a major undertaking, but done right, these can be amazingly warm and comfortable and can protect you for days. There are many different designs, but again (sticking to the principle of this book) getting familiar with one simple technique is almost certainly the best approach unless you are planning to spend a lot of time learning how to dig snow caves!

The technique we prefer is described here.

4. Hypothermia – recognition and treatment

The symptoms of hypothermia can be hard to spot in the early stages, and its onset can be insidious. Unfortunately, treatment becomes harder the longer the situation is allowed to develop so the critical point is to spot the signs early and give the right treatment, or better still provide clothing and shelter before the condition is allowed to develop. Prevention is much better than cure.

It is essential to distinguish between mild hypothermia (defined as a body core temperature below 35 oC) and profound hypothermia (body core temperature below 32 oC) as the treatment is different.

Signs and symptoms of mild hypothermia are:

The victim will feel cold, shiver and have slowed reactions.

They may become apathetic and clumsy and even undergo a character change. Their speech may become slurred.

Signs and symptoms of profound hypothermia are:

At about 32 oC shivering will stop, pulse and breathing will slow.
Further cooling will result in unconsciousness.

If shivering has stopped, you should assume profound hypothermia. The general treatment for mild hypothermia is to prevent further heat loss as the body should then have enough reserves to reheat itself.

Get shelter out of the wind: using any of the techniques described above or any shelter available, the first priority is to get the victim into shelter and out of the wind to reduce the cooling effect.
Insulate the victim from the ground: remember that conductive heat loss can increase rapidly if a victim is lying down.
Change wet clothing for dry: any wet clothing must be removed to prevent further heat loss. Members of the party in good condition may need to give up clothing to the victim, although always being careful not to put more people at risk.
Get the victim into a bivy sac: putting the victim into a bivy sac allows them to gradually re-warm using their own body heat.
Offer food and drink (only if conscious!): food and drink can help considerably with re-warming, provided the victim is still capable of swallowing without choking.
External heat can be applied: from hot drinking bottles if you have a stove to heat up water.
Do not give alcohol!

With profound hypothermia there is an increased risk of cardiac arrest so the victim must be handled gently and not allowed to exert themselves. The general treatment in the field is to slowly re-warm the victim as the body will not have sufficient reserves to reheat itself.

Get shelter out of the wind, insulate the victim from the ground, change wet clothing for dry: exactly as before.
Check the victim’s ABC: as described in the first aid section [LINK], feeling for the pulse every three minutes and remembering that these can be slow.
Slowly re-warm the victim:
· Apply hot drinking water bottles, wrapped in a sock to prevent burning, to the neck, groin and armpits.
· Warm the environment, for example by carefully using a stove in your group shelter.
· Do not apply heat to the limbs as this can increase peripheral circulation causing cooled blood in the limbs to flow back into the body core.
· If no pulse or breathing are present, CPR may not be effective and there is a chance of causing cardiac arrest. If CPR is not given, the heart may recover of its own accord as the body is re-warmed.
No ill effects will be suffered from hypothermia provided it is caught and treated effectively, but vigilance at all times is important to prevent a minor situation deteriorating into a potentially tragic one. Hypothermic victims should in addition always rest for at least 48 hours to allow the body and heart to recover.

5. Frostnip and Frostbite – recognition and treatment

Frostnip is the superficial freezing of tissue (often the cheeks). The area will be painless, numb and have a waxy appearance and feel. The treatment is to cover the area with a hand to re-warm it and then cover with clothing to prevent a recurrance. Frostbite is the freezing of deep tissues. Frostbite should rarely be a major concern in most off-piste conditions, provided the symptoms are spotted and prompt action is taken. The danger signs are:

The body part may feel painful,
Loss of feeling in hands and feet,
The area looks pale and white or (in severe cases) purple.

In cases of frostbite, the victim must be removed for hospital treatment as soon as possible, after treatment for hypothermia or any other injuries. The basic steps in the field are:

Get out fast: if the frostbite is at all serious, the victim must be evacuated immediately since treatment depends on drugs and other processes which you will not have available.
Do not thaw frozen tissue: if the tissue is badly frozen, it is best to get out before attempting any treatment since, for example, walking out on thawed or thawing foot will do more damage than walking out on a frozen foot and getting treatment at a hospital.

With proper clothing and a degree of care, frostbite should not be a major risk in any off-piste skiing environment. The risks are greater in high altitude mountaineering where the precautions should be stricter, and in particular the need to be able to take shelter from bad conditions is paramount.