Q: Do people really freeze to death?
A: Almost 1,000 Americans get hypothermic and die every year; although only in extreme circumstances does their body subsequently freeze. The very old, very young and those with mental impairments (whether congenital or from diseases, alcohol or drugs) are at an increased risk, as are those with prolonged cold exposure from outdoor jobs or recreational activities.
Normal body temperature is 98.6 degrees Fahrenheit; lower than this is hypothermia. Although failure to produce enough body heat due to certain medical conditions can occur, by far the most common cause of hypothermia is excess heat loss. This can happen due to cold exposure without proper insulation to prevent excess radiant heat loss. It is even more pronounced when there is additional conductive heat loss (body heat carried away by direct contact with something cold), most commonly from cold water emersion.
Since body temperature is 98.6 Fahrenheit, emersion in water colder than this can result in hypothermia. The colder the water, the faster the heat loss. Emersion in water that is:
- 60 to 70 degrees Fahrenheit can cause death in two to 40 hours
- 50 to 60 degrees can cause death in one to six hours
- 40 to 50 degrees can cause death in one to three hours
- 32 to 40 degrees can cause death in 30 to 90 minutes
- 32 degrees or less can cause death in as little as 15 to 45 minutes
The degree of hypothermia is usually broken into stages, although the specific temperature ranges for these stages is somewhat arbitrary. For today's discussion I will define stage 1 hypothermia as 95 to 98 degrees Fahrenheit. People with this mild drop in body temperature will feel cold and begin to shiver, although they are able to stop shivering if they try. The victim may feel nauseas and their dexterity will diminish, making complex tasks difficult. Treatment is to get out of the cold and get warmed up.
Stage 2 hypothermia, 90 to 95 degrees Fahrenheit, is a medical emergency. People with this pronounced a drop in body temperature will usually be shivering violently and will not have control over their shivering. Their muscle coordination will be poor, with slow labored movements. They are often confused. These symptoms may make them seem drunk. Treatment is to bring them out of the cold and to begin re-warming while arranging emergent medical care.
Stage 3 hypothermia (temperature less than 90 degrees) is a critical condition, with a high mortality rate. Once body temperature drops this low the patient's shivering response stops. They will be very confused, even delirious, and their muscle coordination so limited they are unable to walk. Their exposed skin will be blue, puffy and fragile. Victims with such low body temperature are at risk for heart arrhythmias, which can be fatal. Even with prompt medical treatment 20 percent or more of patients with body temperature under 90 degrees Fahrenheit die. Once body temperature drops to the low 80s, mortality climbs over 50 percent.
