Hypothermia

Malcolm Cunningham

Definition of Hypothermia

“A decrease in the core body temperature to a level at which normal muscular and cerebral

functions are impaired”

(Medicine for Mountaineering )

How we lose heat to the environment

• Radiation• Conduction

– water conducts heat away from the body 25 times faster than air– Stay dry = stay alive!

• Convection– wind chill

• Evaporation– sweating – insensible perspiration – respiration

Conditions Leading to Hypothermia

• Cold temperatures • Improper clothing and equipment • Wetness particularly with wind • Fatigue, exhaustion • Dehydration • Poor food intake • No knowledge of hypothermia • Alcohol intake - causes vasodilatation

leading to increased heat loss

Times & Places where Hypothermia is Possible

• Above the bushline• Leaving the bush after a sweaty climb

Rain with windSnowing particularly driven wet and sleety snow

• During and after river crossings• Extended in-river travel

Avoiding Hypothermia

• Never wear cotton • Never wear jeans or cotton trousers• Wear wool, polyprop, pile or similar• Put on your parka early • Put on a hat• Put on gloves & overmittens• Put on overtrou – best over long-johns or pile• Have some food

• If you’re cold warn your leader early• Look out for others• Choose your leader carefully

"-Umbles"

stumbles, mumbles, fumbles, & grumbles

which show

changes in motor coordination and levels of consciousness

Mild Hypothermia

• core temperature 37 – 35.6 oC • Shivering - not under voluntary control • Can't do complex motor functions (ice

climbing or skiing) can still walk & talk • Vasoconstriction to periphery

Moderate Hypothermia• core temperature 35.6 – 33.9 oC• dazed consciousness • loss of fine motor coordination -

particularly in hands - can't zip up parka, due to restricted peripheral blood flow

• slurred speech • violent shivering • irrational behaviour• "I don't care attitude"

Severe Hypothermia• core temperature 33.9 - 30 oC and below

(immediately life threatening) • Shivering ceases • Person falls to the ground, can't walk, curls up

into a fetal position to conserve heat • Muscle rigidity develops • Skin is pale • Pupils dilate • Pulse rate decreases • at 32 oC the body shuts down all peripheral

blood flow and reduces breathing rate and heart rate

• at 30 oC the body is in a state of "metabolic icebox." Person looks dead but

is still alive

Death from Hypothermia

• Breathing becomes erratic and very shallow

• Semi-conscious • Cardiac arrythmias develop, any

sudden shock may set off Ventricular Fibrillation

• Heart stops, death

Treating Mild - Moderate Hypothermia

• reduce heat loss • add fuel & fluids • add heat

1. Reduce Heat Loss

• additional layers of clothing • dry clothing • increased physical activity • shelter

2. Add Fuel & Fluids

• give food • give hot liquids• avoid alcohol• avoid caffeine - a diuretic - causes

water loss increasing dehydration

3. Add Heat

Body to body contact. Get into a sleeping bag, in dry clothing with a person in lightweight dry clothing

Treating Severe Hypothermia

• Reduce Heat Loss • Add Fuel & Fluids • Add Heat

1. Reduce Heat Loss

• provide a shell of total insulation for the patient. Use multiple sleeping bags Include an aluminum "space" blanket to help prevent radiant heat loss

• Make sure the patient is dry• has a polypropylene layer to minimize

sweating on the skin • don't put him/her naked in a sleeping

bag with another person.

2. Add Fuel & Fluids

• Warm Sugar Water - for people in severe hypothermia, the stomach has shut down but can absorb water and sugars. Give a dilute mixture of warm water with sugar every 15 minutes.

• Urination – bladder is fuller & body heat wasted on keeping it warm.

3. Add Heat

• heat can be applied to transfer heat to major arteries - at the neck for the carotid, at the armpits for the brachial, at the groin for the femoral, at the palms of the hands for the arterial arch

• use hot water bottles, warm rocks, towels, compresses

• rescue breathing can increase oxygen and provide internal heat

WEEKEND 25-26 FEB

Platform 98 am

1. NeilNicola

TimLucas

2. DanielMurrayHelen

JeffAlison

4. PatrickGrantKeithJackie

Jacquie

3. HaydenColin

MeganSusanTracy

5. AlisonKatieGim

Mary

Some Off-Track Principles

1. Always understand the lay of the land around you2. Travel on ridges3. When leaving the main range to go down a ridge:

(a) study your map carefully and decide which ridge you will go down

(b) before proceeding take time to confirm you are at the right place to start down

4. Walk down the ridge on a compass bearing5. Be aware of where the sun should be6. Never, never go down a stream or a gully unless you know it7. Ridges broaden at the bottom. Work hard to stay out of gullies8. If you come to a Y climb out sideways to find another ridge9. If you slip off the ridge climb straight back up, don’t sidle10. If you’re on an old track it’s worth working hard to stay on it11. In untracked rivers walk the flats and climb and sidle the gorges12. BUT sidling is fraught. Check the map to see how to minimise

problems (is there a terrace? Is there a shoulder to climb through at the collar bone?)