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Hypothermia: You're Not Just Cool (Dude)


by Sean Hudson

December 29, 2001

It always happens during the day trips that turn into epics or those weekends when the weather was supposed to be stable. The dangers of hypothermia will quietly slip up on you when you aren’t prepared. Mother Nature has a merciless way of reminding you to pay your respects and not underestimate her mountains. Hypothermia can be deadly, this article will help you better understand how it affects you, how to avoid it and how to treat it.

Hypothermia is defined as the drop of central temperature below 35° Celsius. Traditionally, hypothermia is considered as moderate above 32°, serious between 32° and 25° and major under 25°.(2) But its severity depends on the patient's condition, the cause and the rate of its onset. Symptoms of hypothermia include: slow or irregular speech, shallow breathing, fatigue, confusion, slow pulse, weakness, drowsiness, shivering, and cool pale skin. These symptoms are not necessarily listed in the order they would occur. There are many factors that can take a person into a hypothermic state. Wetness, cold temperatures, injuries, inadequate clothing or equipment, and insufficient food and water intake are the most common and most obvious.

So exactly what would you call hypothermic temperatures, and what are the different levels of hypothermia? (1) (From Outdoor Action Guide to Hypothermia And Cold Weather Injuries by: Rick Curtis)

Mild Hypothermia

  • core temperature 98.6 - 96 degrees F
  • 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 95 - 93 degrees F
  • 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

Severe Hypothermia

  • core temperature 92 - 86 degrees 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 the body tries to move into hibernation, shutting down all peripheral blood flow and reducing breathing rate and heart rate.
  • at 86 degrees the body is in a state of "metabolic icebox." The 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

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
  • 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.

From 1988 to 1996, 117 hypothermia victims have been treated in Chamonix hospital. 40% of them were under 32°. The common causes are isolation in bad weather (48%), falls in narrow crevasses (40%) and for a lesser part avalanches (12%). Pure hypothermia only represents 22% of the cases. Associated injuries are essentially from the head (50%), spine (12%), abdomen (18%) and thorax (4%). Overall mortality is 22%, but these patients suffer from other injuries in 95% of cases. On the whole, these figures lead to the two following principles: (2)

Basic Life Support

If the victim is not breathing, rescue breathing should be initiated. Cardiopulmonary resuscitation (CPR) in the pulse-less patient should be begun immediately, although pulse and respirations may need to be checked for longer periods to detect minimal cardiopulmonary efforts. The traditional recommendation that pulse and respiration's be checked for 1 to 2 minutes before beginning CPR is probably excessive. A span of 30 to 45 seconds should be adequate to confirm pulselessness or profound bradycardia, for which CPR would be required. It is important to prevent further heat loss from the patient's body core by removing wet garments from the victim, insulating the victim, shielding him or her from wind, and ventilating with warm, humidified oxygen. For victims not in cardiac arrest with temperatures of 30° C to 34° C (86° F to 93° F), apply external warming devices to truncal areas only (warm packs to neck, armpits, and groin). After stabilization, cautiously ready the patient for transport to a hospital. (2)

Hopefully you will never have to resort to using the information in the last paragraph, but now you have read it hopefully you have a better understanding. This article is not intended to teach you all about hypothermia. It is designed to give you a better understanding of the seriousness of hypothermia and to provide further resources for your education and understanding of how to treat (or better yet) how to avoid hypothermia.


  1. Outdoor Action Guide to Hypothermia And Cold Weather Injuries
  2. Mountain Medicine and Traumatology Department of Chamonix Hospital (DMTM)

Other Resources:


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