Hypothermia
By Dr Beth Hall-Thompson
The average temperature on the summit of Everest in the summer climbing season (May) is -17C (0F) – at 6pm in the evening; and we are hoping to make the summit by latest 2pm so it should be a bit warmer! But then we have to add wind chill factor – add the average wind speed factor in and the summit temperature becomes -53C (63F)! So let’s say we won’t be hanging around on top for too long!
But we will be exposed to extreme cold for the entire 6 weeks that we lay siege to the mountain; the average evening temperature at base camp is just below zero, and so the down jacket will be an almost permanent layer.
There are two real problems associated with the cold – whole body cold injury - Hypothermia; and localised injury – Frostbite. Both are threats to our lives as if our hands/feet aren’t working then all climbing becomes unsafe. Here I am just going to look at hypothermia; and deal with frostbite – a more likely scenario – in a separate link
What happens to the body?
Physiologically the cooling process is the same in the core as in the limbs – to protect ourselves we automatically constrict the non-vital blood vessels so ensuring that heat doesn’t get lost from our extremities; and ensuring a warm blood supply to the heart, lungs, kidneys and brain. We also increase our metabolic rate, using up extra calories, in order to shiver and produce body heat. But there is only so long we can manage to shiver – muscles and energy tire; loss of the shivering response is a bad sign and heralds the start of deterioration that affects rationale thinking. The casualty is now beyond helping themselves and in fact may go through the ‘undressing paradox’ prior to eventually succumbing to the cold. A significant number of those who die in cold environments, including 1 unfortunate climber on the north face of Everest, take off a large proportion of their clothes, and in many cases fold them neatly, prior to death. The full pathology of this phenomenon is unknown but this stage is recognised to be fatal, and demonstrates the reduced mental function that cold causes.
So how are we going to prevent hypothermia striking within the team?
Education is one of the key points; we have all worked and climbed in cold places before but nowhere else is this extreme (except the North Pole). So we, and the team doctor, will be reminding us of the best preventative measures and these will become automatic drills in time.
- Ensure we stay well hydrated and fed, including hot food intake – even when we can’t be bothered.
- Do not let our clothing become wet; if it does then it needs changed asap.
- Insulate with the best clothing possible; don’t forget head and neck too!
- Do not leave any body part exposed to the temperature for any length of time.
- Most importantly – look out for each other; learn to recognise the signs and symptoms; and take action. This is called Buddy-Buddy aid – and is a principle applied to all health and safety aspects in both the military and on the mountain.
The team doctor will be available to us at base camp but no higher, and in this environment, staying in one place to treat hypothermia may well add to the problem, so it needs to be recognised fast and reversed rapidly. We will have radio contact throughout however so that we can take advice.
What we will be looking for (Signs and Symptoms):
Mild hypothermia (32-35C)
Shivering, poor judgement, apathy, forgetfulness, slurring of speech; other signs like high breathing and heart rate are no use to us on the mountain – they will already be high due to altitude and exertion.
Moderate hypothermia (28-32C)
Loss of shivering, a reduced breathing rate, paradoxical undressing, dilated pupils
Severe hypothermia <28C
Most people with body temperatures below 28C are comatose – this is not a stage that any of us should be allowed to reach – our well practised Buddy-Buddy Aid will prevent it; but it is not unlikely that we may meet other climbers on the mountain who are severely affected.
First Aid for Hypothermia
- Shelter – get out of the wind
- Check that there are no exposed body parts; if so add a layer of clothing
- Provide fluid; warm if possible, and food where appropriate.
- Assess the situation quickly; is this mild and can it be treated so that they can continue or do we need to get them down to prevent worsening of the hypothermia. Continuing to move, even downwards, at least keeps the muscles pumping some warm blood around the body.