“When you’re losing heat at a higher rate than you are producing it, you have hypothermia.”
When your core temperature is less than 35°c you have hypothermia (should be 36.5-37.5°c).”
How do you get hypothermia?
You can get hypothermia by being exposed to prolonged cold conditions or being immersed in cold water. In these cases, you lose heat quicker than you produce it. Practical example: After a tough ascent, you’ll have been sweating and your clothes will be damp, this will pull heat from your body and you may not even think you’re at risk. Knowing the information below may save your life or help you save somebody’s life.
What symptoms would someone with hypothermia have?
The obvious first symptom of hypothermia is shivering. We’ve all shivered of course so we’ll often let this one pass without thinking we’re hypothermic.
Confusion, very low energy levels and a lack of coordination may follow. Slurred speech, shallow breathing and a weak pulse may also be present, even a loss of consciousness.
When your core temperature drops to 28-30c your heat rate will be in the 30s! You’re severely hypothermic now.
By this time, you’ll be very pale, your lips, ears, nose, fingers and toes may be blue.
Soon you’ll be stripping off and digging a hole (this does actually happen).
Heat loss – (Physical science that stays the same for everyone)
We lose heat in 3 ways.
When your skin touches something colder, heat energy will just be sucked from it. If you fall into cold water, heat loss will of course be much greater than exposure to the air. If you have been sweating or you’re wet from the rain you’ll lose heat in this way, faster than you anticipate. During Storm Oscar, heading for a night in the Black Sail Hut on our Autumn Retreat the group was soaked enough before the river crossing.
Think of heat waves just radiating from uncovered areas of your skin, especially your face and hands.
Our hair and clothing create a layer of warm air around our skin. When you don’t tuck your clothes in, zip your coat up, tuck your trousers in, etc. wind will disturb this warm layer of air and carry it away. This will play a big part in you losing heat.
Are you at risk?
If you are ‘getting on a bit’ or you are a child you have a higher risk of getting hypothermia.
After ascending a mountain, being very tired, you’re at risk of getting hypothermia.
If you consume alcohol, your blood vessels expand, increasing heat loss from your skin. Your ability to shiver will be diminished and your journey to hypothermia will be quicker. Although you may think you can take on the world, your judgement will be impaired so you’ll be less likely to be able to take on hypothermia. Although alcohol makes you ‘feel’ warmer, this is simply heat leaving your skin. Leave that flask of whisky in the house.
Children are too busy having fun to judge whether they are cold or not, until it is often too late. Yesterday (in November) my son, off to play in the park (in the Northern Lake District) was happy to leave without a coat, hat or gloves. As his parent it’s my responsibility to wrap him up and remind him that if his fingers and toes get cold it’s because his body is preserving heat as it’s getting too cold. He came back because his ‘toes were cold’.
Anyone suffering from any kind of trauma, underactive thyroid (hypothyroidism), diabetes, anorexia or poor nutrition, stroke, arthritis, Parkinson’s disease or spinal injuries are also high risk.
Hypothermia can also result in the frostnip, frostbite and even your heart stopping.
So, how can you prevent hypothermia?
The best prevention of course is to stay at home with the central heating on. If you really must live life to the full, go out and have fun, participate in such adventurous activities; follow these guidelines.
Stop the heat from getting out by conduction, radiation and convection. Layers of clothing create layers of warm air which reduce heat loss. Make sure that your layers are tucked in, you don’t always feel the wind under a coat when you have a shirt and fleece on. Wearing a snood can help stop the wind carrying heat from around your neck.
I grew up with ‘a third of your heat loss is through your head’ rammed into my ears. I always wear a hat, sometimes in the house, always in my sleeping bag on a summit.
Mittens create a warm layer of air around your hands. If mittens are wet you’ll lose less heat than wearing gloves, although you’ll have to take mittens off more to do things you could do if you had gloves on though! I wear gloves with Goretex mittens over the top.
Don’t wear cotton! It holds on to moisture which increases heat loss through conduction. Invest in clothing that wicks, drawing moisture away from your body, and a coat that will expel moisture and keep wind off you, made from a material like Gortex, or look into Paramo jackets.
Stay dry, or get dry as soon as you can. If you are camping, get into dry pyjamas before you get into your nice dry sleeping bag. If you’re on an expedition of more than a couple of days, hang your bag up inside out so your night sweat disperses which you have breakfast and pack, this may not work in freezing or very humid conditions anyway but if the opportunity arises use it.
Even if you’re only going out of the day, you could take a stove. Tea bags don’t weigh anything. Cup soups will make a surprising difference to your mood as well as warm you up. In the photo above on day 2 of an extended Coledale Horseshoe I had a migraine, was freezing and had no water. I scooped up some fresh snow and heated it on the stove, honestly that was the best cup of tea I’ve ever drank.
If you really must have adventures make sure you are well prepared. Going to bed on Eel Crag that night the temperature outside at 8pm was -10c. I have an Alpkit Skyehigh 750 sleeping bag and my thermometer read 30c all night so I was toasty. The heat was produced by me, or rather my gut, digesting the food I’d eaten.
You’re safer in a group. A group will be more likely to make rational decisions when things go wrong, get out of dodge or call Mountain Rescue if the need arises.
Come on one of our Wild Camping Workshops and we’ll teach you all about staying warm camping through Winter nights.
How to get warm if you have hypothermia.
If you are intolerably cold you should really get out of the elements. If you’re walking with me I will be carrying a group shelter. Getting out of the wind will make a world of difference. The above photo shows a woman who was complaining that she was freezing 15 minutes previous, now sheltered, having had lunch, moral was higher than any other point on the hike.
Although food with quick releasing sugars won’t warm you for long, you really need a quick boost of energy. Carrying more than enough high energy snack bars may save your life. I carry half a dozen bars in case someone I’m with needs something, maybe you’ll even stumble across a casualty along the trail.
To further reduce heat loss, sit or lie down, off the cold ground using heather, branches or bracken to make an elevated seat. Use a sleeping mattress if you’re out camping. Get out of wet clothes into something dry. Wrap up in a sleeping bag. Cover your head.
When you do get down and you’re passing an inn with a log fire, don’t just pass it by, get in there to dry out, order coffee and chocolate cake for good measure.
Wild camping at a frozen Innominate Tarn on Haystacks.Wild camping at a frozen Innominate Tarn on Haystacks.
Wild camping at a frozen Innominate Tarn on Haystacks.
If your vehicle breaks down or you are involved in an accident you may have to spend some time in it before help comes. You should have extra dry clothes, water and food to hand. A stove and a tin of tomato soup would be welcomed by a cold child.
Send the word ‘Register‘ by text to 999 to register your phone.
In emergency, call 999 and ask for the Police, then Mountain Rescue. If you can’t get a signal, text ‘Police, the incident details and your location (ideally your grid reference)’ to 999 BUT you must have registered with the text service beforehand. Wear bright colours so Mountain Rescue can see you and stay where you are. If you must move, let Mountain Rescue know where you are going.
Notes in conclusion
Of course, hypothermia is simply your body losing more heat than it is producing. To prevent this, you must produce more heat. We produce heat by eating. Some foods are better than others in helping you produce heat within, but that is a whole new blog!
Don’t let this information put you off having fun and enjoying a walk in the Autumn or Winter, just get to know what you need to, be prepared. If you need a day with me learning general hiking skills drop me a line or book here –
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Have a happy and warm Winter.
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