Hypothermia occurs when the body loses heat faster than it can generate it, leading to a situation where the body core is unable to maintain sufficient warmth to allow the proper function of vital organs.

Wet, wind and cold are the key environmental factors that cause hypothermia. Any two of these is enough to start the cooling process in earnest.

As you move it is important to vent the moisture your body is creating as you exert yourself. At the same time you will attempt to protect yourself against the wind and rain. It is vital to keep your base layer as dry as possible, as wet or damp clothing against your body will cause you to lose heat 25 times faster than when dry.

A few degrees is all it takes!

  • Normal body core temperature is 37C. The skin is usually cooler by a few degrees.

  • Shivering occurs when core temperature 35C. The body is automatically trying to produce warmth by muscular activity.

  • Below 35C, we start to experience clumsiness, irrational behaviour and generally confused state. A person may appear to be drunk. At this stage the person suffering is almost exhausted and unable to produce body heat, let alone keep moving. Exercising the person will only increase the hypothermia. It would be dangerous to take the person suffering from hypothermia into a warm room as it can cause the blood to rush from the core to the extremities which suddenly may sent the person into a coma.

  • At 33C the person will be shivering, incoherent and complain of aching stiff muscles. They are now on the edge of severe hypothermia. If the temperature continues to drop they will slip into unconsciousness and may lose response to painful stimulus.

  • At 28C the person will give the appearance of death. It is important not to give up on treatment. There have been several cases where the person has made a full recovery having been kept alive by rescue breathing and CPR for several hours! For this reason a doctor will only pronounce the person dead when the body has returned to room temperature.

Dealing with a hypothermic case in the wilds is very difficult and it is better to concentrate on spotting the symptoms and prevent it occurring, rather than trying to reheat a patient. 

Before you start

Ensure you and everyone in your party is carrying the right layering material to suit the weather conditions you are walking in and you willingly stop regularly to out them on. In essence you want to try and keep your base layer as dry as possible by continually varying your layers to suit your activity and weather conditions.

Why layer?

A base layer which wicks moisture away from your skin is vital to prevent the increase of heat loss. A simple highly breathable windshirt prevents windchill/convection. An insulating layer which you put on at rest stops or periods of low activity keep the heat in. Finally a waterproof jacket to prevent rain or cold weather penetrating your layers and soaking you ‘to the skin’, which then increases heat loss once again. Warm headwear prevents 47% of heat loss and gloves to keep your hands mobile. The wicking headwear made by Matt and Buff work well as a wicking layer for the head and neck in the right conditions, but once sodden by rain or sweat, they need to be replaced by thicker, warmer headwear.

Once on the hill

Once you or any of your party start to feel ‘chilled to the bone’, ‘frozen and shattered’, ‘shivering’ or ‘soaked to the skin’ you are in the first stages of hypothermia and it is absolutely vital to deal with this immediately. (This is the easiest stage to resolve and you will regret it if you don’t). Stop, rest, get out of the wind/rain, put on the correct clothing, drink water, eat something sweet and make sure your body warms up before deciding to continue or vary your route for safety reasons.

If walking with others who may be suffering, do not push on ahead and ignore them thinking they will cope or it will get better. This increases their despondency and accelerates their medical decline. Positive mental attitude (PMA) is a vital component in dealing with issues like this on the hills. Be supportive, ask questions and ensure they take on board water and sugar in some form. This can be difficult if dealing with children, or a group which wants to ‘press on’, but even more important for reasons stated above. Then make a decision to consider your best route options...

Remember, the hills will still be there tomorrow!