Hypothermia is a danger whenever the temperature drops or you get wet and can’t dry out. It’s important to know the basics of hypothermia, how to identify it, and how to treat mild cases. Hypothermia is when your core body temperature drops and your body functions are hindered, which can eventually lead to death.
There are 4 ways we lose heat:
1. Radiation – loss of heat to the environment due to the temperature gradient (difference). This occurs whenever the ambient temperature is below 98.6 F or 37 C. Factors important in radiant heat loss are the surface area and the temperature difference.
2. Conduction – through direct contact between objects
Water conducts heat away from the body 25 times faster than air because it has a greater density (therefore a greater heat capacity). Stay dry = stay alive!
Example: Generally conductive heat loss accounts for only about 2% of overall loss. However, with wet clothes the loss is increased 5 times.
3. Convection is a process of conduction where one of the objects is in motion. Molecules against the surface are heated, move away, and are replaced by new molecules which are also heated. The rate of convective heat loss depends on the density of the moving substance (water convection occurs more quickly than air convection) and the velocity of the moving substance. Wind Chill is an example of the effects of air convection.
4. Evaporation – heat loss from converting water from a liquid to a gas
– Perspiration – evaporation of water to remove excess heat
– Sweating – body response to remove excess heat
– Respiration – heat lost in water vapour that is exhaled
It is important to recognize the strong connection between fluid levels, fluid loss, and heat loss. As body moisture is lost through the various evaporative processes the overall circulating volume is reduced which can lead to dehydration. This decrease in fluid level makes the body more susceptible to hypothermia and other cold injuries.
Conditions Leading to Hypothermia
– Cold temperatures
– Improper clothing and equipment
– Wetness
– Fatigue, exhaustion
– Dehydration
– Poor food intake
– No knowledge of hypothermia
– Alcohol intake – causes vasodilation leading to increased heat loss
Signs and Symptoms of Hypothermia
a. Watch for the “-Umbles” – stumbles, mumbles, fumbles, and grumbles which show changes in motor coordination and levels of consciousness.
b. Mild Hypothermia – core temperature 98.6 – 96 degrees F (37 – 35.5 C)
– Shivering – not under voluntary control
– Can’t do complex motor functions (ice climbing or skiing) but can still walk & talk
– Vasoconstriction to periphery
c. Moderate Hypothermia – core temperature 95 – 93 degrees F (35 – 34 C)
– 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 behavior – Paradoxical Undressing – person starts to take off clothing, unaware s/he is cold
– “I don’t care attitude” – flattened affect
d. Severe Hypothermia – core temperature 92 – 86 degrees F (33 – 30 C) and below (immediately life threatening)
– Shivering occurs in waves, violent then pause, pauses get longer until shivering finally ceases – because the heat output from burning glycogen in the muscles is not sufficient to counteract the continually dropping core temperature, the body shuts down on shivering to conserve glucose.
– Person falls to the ground, can’t walk, curls up into a fetal position to conserve heat
– Muscle rigidity develops – because peripheral blood flow is reduced and due to lactic acid and CO2 buildup in the muscles
– Skin is pale
– Pupils dilate
– Pulse rate decreases
– At 90 degrees F (32 C) the body tries to move into hibernation, shutting down all peripheral blood flow and reducing breathing rate and heart rate.
– At 86 degrees F (30 C) the body is in a state of “metabolic icebox.” The person looks dead but is still alive.
e. 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
How to Assess if Someone is Hypothermic
– If shivering can be stopped voluntarily = mild hypothermia
– Ask the person a question that requires higher reasoning in the brain (count backwards from 100 by 9’s). If the person is hypothermic, they won’t be able to do it. [Note: there are also other conditions such as altitude sickness that can also cause the same condition.]
– If shivering cannot be stopped voluntarily = moderate – severe hypothermia
– If you can’t get a radial pulse at the wrist it indicates a core temp below 90 – 86 degrees (32 – 30 C)
– The person may be curled up in a fetal position. Try to open their arm up from the fetal position, if it curls back up, the person is alive. Dead muscles won’t contract only live muscles.
Treating Mild or Moderate Hypothermia
1. Reduce Heat Loss
– Additional layers of clothing
– Dry clothing
– Increased physical activity
– Shelter
2. Add Fuel & Fluids
It is essential to keep a hypothermic person adequately hydrated and fueled.
a. Food types
– Carbohydrates – 5 calories/gram – quickly released into blood stream for sudden brief heat surge – these are the best to use for quick energy intake especially for mild cases of hypothermia.
– Proteins – 5 calories/gram – slowly released – heat given off over a longer period.
– Fats – 9 calories/gram – slowly released but are good because they release heat over a long period, however, it takes more energy to break fats down into glucose – also takes more water to break down fats leading to increased fluid loss.
b. Food intake
– Hot liquids – calories plus heat source
– Sugars (kindling)
– GORP – has both carbohydrates (sticks) and proteins/fats (logs)
c. Things to avoid
– Alcohol – a vasodilator – increases peripheral heat loss
– Caffeine – a diuretic – causes water loss increasing dehydration
– Tobacco/nicotine – a vasoconstrictor, increases risk of frostbite
3. Add Heat
– Fire or other external heat source
– Body to body contact. Get into a sleeping bag, in dry clothing with a normo-thermic person in lightweight dry clothing
Severe Hypothermia
For severe hypothermia, you will need medical attention — use the 9-1-1 button on the SPOT device. In the mean time, you can follow these steps:
1. Reduce Heat Loss
Hypothermia Wrap: The idea is to provide a shell of total insulation for the patient. No matter how cold, patients can still internally rewarm themselves much more efficiently than any external rewarming. Make sure the patient is dry, and has a polypropylene layer to minimize sweating on the skin. The person must be protected from any moisture in the environment. Use multiple sleeping bags, wool blankets, wool clothing, Ensolite pads to create a minimum of 4″ of insulation all the way around the patient, especially between the patient and the ground. Include an aluminum “space” blanket to help prevent radiant heat loss, and wrap the entire ensemble in plastic to protect from wind and water. If someone is truly hypothermic, 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 and will not digest solid food but can absorb water and sugars. Give a dilute mixture of warm water with sugar every 15 minutes. Dilute Jello™ works best since it is part sugar and part protein. This will be absorbed directly into the blood stream providing the necessary calories to allow the person to rewarm themselves. One box of Jello = 500 Kilocalories of heat energy. Do not give full strength Jello even in liquid form, it is too concentrated and will not be absorbed.
Urination. People will have to urinate from cold diuresis. Vasoconstriction creates greater volume pressure in the blood stream. The kidneys pull off excess fluid to reduce the pressure. A full bladder results in body heat being used to keep urine warm rather than vital organs. Once the person has urinated, it precious body heat will be used to maintain the temperature of vital organs. So in the end urinating will help conserve heat. You will need to help the person urinate. Open up the Hypothermia Wrap enough to do this and then cover them back up. You will need to keep them hydrated with the dilute Jello solution described above.
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.
– Chemical heat packs such as the Heat Wave™ provides 110 degrees F (43 C) for 6-10 hours.
– Hot water bottles, warm rocks, towels, compresses
– For a severely hypothermic person, rescue breathing can increase oxygen and provide internal heat.
Majority of the info for this post comes from here.