Hypothermia - Essential Advice For Walkers & Mountaineers
Mountain first aid expert Helen Howe takes an in-depth look at the symptoms of hypothermia, how to treat it and how to avoid it in the first place.
Winter is upon us, and with it an increased hazard of hypothermia. Strangely enough, the danger from snowy and icy weather is not necessarily greater than from milder temperatures combined with wind and rain - typical winter conditions this year! This article looks at hypothermia, how to recognise the different stages, how to treat or manage it and equally importantly, how to avoid getting it.
What is Hypothermia?
There are many ways of classifying hypothermia, from the Swiss way of four stages, to the usual British classifications Mild, Moderate and Severe. Hypothermia is defined as being when the body's core temperature drops below 35C. However, one important thing to remember is that whatever the classifications everybody is different, and so people will feel cold and start to shiver at different temperatures. Without having thermometers capable of reading internal core temperature (and would we really want to expose a hypothermic casualty in order to do that?), the easiest classification is Mild (casualty cold and shivering) and Severe (casualty cold and not shivering). I'll cover both in some detail below.
On rare occasions, immersion hypothermia may occur where someone falls into a stream or river and is cooled instantly. But in the mountains the most usual cause of hypothermia is exposure, where someone has gradually depleted their body's resources in exertion and trying to keep warm in bad conditions.
Recognition and Treatment of Hypothermia
At the mild stage the person is able to shiver as they still have fuel on board. Shivering is an extremely effective way of re-warming and can raise the body temperature by up to 4C an hour if enough food and fluid supplies the energy needed. Once the body has run out of energy, however, it no longer has the means to warm itself. At this point shivering stops and the person cannot be re-warmed on the hill. This is now severe hypothermia.
As a winter walker or mountaineer, it is possible that someone in your group, or even yourself, gets caught out by mild hypothermia. It may be that we have kept going that little bit longer than we should have done because we want to get to better shelter to put that extra layer on, or grab a bite to eat, or we are succumbing to peer pressure and not wanting to make an issue of feeling cold, causing the whole group to stop while we put an extra layer on. Luckily mild hypothermia should be easy to reverse in its early stages.
Early signs and symptoms of Mild Hypothermia:
- Casualty looks and feels cold
- Shivering often violent and uncontrollable
- Pale skin
- Blue lips
Later signs - it's getting more serious:
- Slurring words
- Shivering becoming weak
- The Umbles; stumble, mumble, grumble, fumble etc
Treatment of Mild Hypothermia:
- Stop and seek shelter
- Add more layers. If clothing is soaked then it may need removing but realistically very few of us carry enough spare clothing to both fully re-clothe a hypothermic casualty and keep ourselves warm. I tend to go for the wetsuit approach; unless the casualty's bottom layer is totally saturated, add more layers on top and make sure that you cut out the wind and rain.
- Vapour Barrier. This is something like a Blizzard Vest which traps heat and stops air movement for evaporation
- Food for energy; the higher energy, the better
- Warm or hot drinks; heat straight into the core of the body is great for warming
- If necessary hands can be warmed by body contact from other people
- Once refuelled and warmer, get moving. If they have enough fuel (energy) on board walking will now help to warm them up
Hopefully you will never be in a party where a member goes down with severe hypothermia. For this to happen, many of the early warning signs will have been ignored. It is more likely that this is an individual walker that you come across in the hills. Often it may be someone who has become trapped by icy conditions, injury or steep terrain and so rendered immobile.
With someone in severe hypothermia it can be extremely difficult to detect whether they are alive or dead. Their breathing and heart rate may have become so slow and shallow that it is almost impossible to find - especially in the sort of conditions in which they are likely to have succumbed to hypothermia. Their pupils may be fixed and dilated. They may have no response, and appear dead.
Here's a good rule: No one is ever cold and dead, they are only ever warm and dead. Unless they have other signs incompatible with life, treat them as living casualties.
Treat this casualty with as much care as possible. We always say treat them as though they had spinal injuries. If they are still alive, any large movements could send cold blood to their weakened heart, putting it into VF (Ventricular Fibrillation). This is an abnormal heart rhythm where the heart muscles contract in an uncoordinated manner out of rhythm with each other. It is life threatening, and can only be reversed by an AED machine. So keep their head and heart above their legs and avoid sending cold blood from their extremities and legs to their heart.
Remember they also need to be insulated from the ground as well as from the air and elements. The ground is like a giant sponge sucking the warmth out of them. Use their rucksack or anything else you have. But again be gentle with them.
If there are no signs of life, do I start CPR?
This is a really tricky question to answer. At one time I would have said a categorical no, as the casualty may be breathing and have a pulse but it may be undetectable due to them being so slow and shallow and weak. CPR could do exactly what we had wanted to avoid, i.e. pump cold blood into the heart and trigger VF. This was once irreversible on the hill, and once a rescue team put a casualty onto a stretcher they could not continue CPR to sustain life. However some teams in the UK now carry an Autopulse machine which is able to carry out artificial heart compressions. The problem is that not all teams yet use them: As a result some teams would be able to carry out CPR on a stretcher in the evacuation and others would not. After you have initiated the 999 call, I think the best thing to do (where there is enough signal) is to ask the rescue team co-ordinator who phones you for information what they would like you to do.
Do also consider whether you can continue CPR for however long it takes until rescue arrives. That will be based on the weather conditions, your own state, and whether a helicopter could get in to your location or close by.
Signs of Severe Hypothermia:
- Pale skin and blue lips
- No longer shivering
- Barely able to function
- May be or become unconscious
- May only respond to pain
- Fixed, dilated pupils
- May be totally unresponsive
Management of Severe Hypothermia:
- Insulate from ground and air as gently as possible
- Make sure that the layers are water and windproof
- Do not risk members of your party trying to reheat them in a bivvy bag by buddying up. The casualty is past that and it would just put the others at risk of getting colder.
- Rub energy gel onto gums (it may make a difference if they are right on the edge of Mild/Severe) and give their body a boost of energy to start them shivering again. However be careful as you do not want to get gel anywhere near the back of their throat
- Call 999
- With minimal movements get them into a safe airway position if they are unresponsive, ensuring their heart remains above their legs.
- If you cannot detect breathing then check with the MRT whether you should start CPR (there is a danger that starting it may trigger VF so once CPR has been started it should be continued all the way to hospital and it may not be possible for rescue teams to do this on a stretcher.)
So How Can You Avoid Hypothermia?
Carry the right gear to cut out wind and rain.
Essential winter equipment to help prevent or treat hypothermia:
- Waterproof jacket and trousers
- Good gloves and hat (and spares)
- Good insulating layers (synthetic insulation is better than down as it works better when wet)
- Flask with hot drink
- Plenty of high energy food
- Blizzard vest/sleeping bag
- Group shelter
Listen to your body
All of us have had a day where we just dont feel as strong or fit. It may be that your body is trying to tell you something such as it is fighting a virus. If so, ignore it at your peril. Do not push to the point of no return in the mountains.
Always have a Plan B or escape route
Even if you have checked the forecast, sometimes bad weather comes in a lot faster and earlier than forecast. Be prepared for this by having at least one escape route.
Make sure you can navigate in bad conditions
Becoming immobile in the mountains is not good. It takes so much energy to build a snow shelter or hole that it takes precious energy from your body. It is normally better to try to get off the hill than waste time and energy building a shelter.
One good motto in winter is BE BOTHERED! If you feel cold, stop and get another layer on. If you are hungry, eat something. Do not get into the trap that you can't be bothered to stop because you feel too cold. If you aren't happy, or think you have bitten off more than you can chew, retreat.
About Helen Howe
Helen runs Snowdonia First Aid with her husband Steve.
Each have over twenty years of Scottish winters and are qualified Winter and International Mountain Leaders. They run Outdoor First Aid courses and Mountain Leader Training and Assessments as well as mountain and hill skills courses. This winter Helen and Steve are running Winter Skills courses both in Snowdonia and Scotland.
Helen is also a qualified Mountain Rescue Dog handler who has trained three SARDA dogs. Both she and Steve are active members of Llanberis Mountain Rescue Team and have served on the Medical and Training Sub committees running some of the team's winter training.