Hypothermia--Slowly Freezing to Death

A normal internal (core) body temperature is 98.6 F (37 C). Hypothermia occurs when the body is subjected to a cold environment for a long enough period of time that the internal body temperature drops to less than 95 F (35 C). Hypothermia can also occur when the body’s temperature regulation system is deranged.

Inside the brain, the hypothalamus (a primitive part of the brain) is responsible for temperature control. Normal metabolic processes generate the body’s heat. When too much heat is lost through the skin (or in the case of fever) shivering produces heat through muscle action.

Continued heat loss results in shunting of blood away from the skin internally, to support the internal organs—especially heart and brain. As the body’s core temperature drops, metabolic processes slow, and the heart rate, respiratory rate, and brain waves all slow down. As the internal temperature continues to drop, death will ensue.

Environmental exposure accounts for the vast majority of hypothermia. Individuals with alcohol on board are more susceptible as alcohol dilates the skin vessels and accelerates heat loss; drinking brandy to “stay warm” while scooping snow is a bad idea! Low thyroid, advanced age, drug abuse, and some medications (vasodilator drugs) increase the likelihood of environmentally-induced hypothermia. Psychiatric conditions like dementia—that might cause an individual to wander away without a defined destination—are a risk factor.

Brain conditions that affect thermoregulation ability can put someone at risk.

The gradual onset of hypothermia makes it harder for someone to know what’s happening. Onset may lead to a phenomenon known as paradoxical undressing, where the person sheds clothing even though they’re freezing to death. Drowsiness, followed by drifting into sleep and death follows.

Treatment involves getting the person to a warm environment, out of wet clothes (if applicable) and rewarming. External warmth—hot water bottles, warming blanket, even body-to-body contact—is applied. In a medical setting, warm IV fluids, warmed air, and heated blankets can be used. Warm fluid can be infused into the abdominal cavity.

In worst-case scenarios, the patient can be rewarmed using heart-lung bypass, warming the blood as it goes through the machine.

Caution for heart rhythm disturbances involves avoiding moving the patient more than necessary. As people with profound hypothermia have been successfully resuscitated, most doctors consider a hypothermic patient to be potentially salvageable until they are warm.

The biggest consideration is to avoid situations that may lead to hypothermia, primarily avoiding prolonged exposure to cold weather.

 

Questions? Comments?

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Kelly has worked in the medical field for over twenty years, mainly at large medical centers. With experience in a variety of settings, chances are Kelly may have seen it.
Sometimes truth seems stranger than fiction in medicine, but accurate medicine in fiction is fabulous.
Find Kelly’s fiction at www.kellywhitley.com

Frostbite and the Frozen Character

In honor of April blizzards, here's a bit about what would happen if your character got stranded and had to walk a distance through snow.

 

Mechanism of Frostbite

A normal body temperature is 98.6 F or 37 C. Frostbite occurs when body tissue is exposed to temperatures below the freezing point of water (32 F or 0 C).

The majority of cases of hypothermia occur due to exposure outdoors. Alcohol worsens the problem, as does malnutrition, dehydration, and physical exhaustion.

The areas farthest from the heart are most susceptible: fingers, toes, nose, ears, and the face in general.  

With cold exposure, blood vessels constrict in the extremities (arms and legs) to centralize blood flow to the vital organs and maintain core temperature. These remote areas get progressively colder. Brief dilatation of extremity vessels alternates with constriction. As the body temperature begins to drop, the vessels remain constricted. This is the point at which frostbite begins.

The damage from cold is of two types: ice crystals form between cells, leading to cellular dehydration, and blood vessel damage leading to lack of oxygen to cells.

Degrees of frostbite

First degree: Freezing of the top layer of the skin, but still gives to pressure. Numbness, itching, and some pain. No permanent damage.

Second degree: The skin hardens as it freezes. Blisters form. Usually heals, but may have some insensitivity to temperature long term.

Third degree: Freezing into the deeper layers—the skin, muscles, nerves and vessels are affected. Blisters form, which are blood-filled. Permanent damage leading to the need for amputation can occur. The situation is a complicated mix of clotting in small blood vessels, inflammation, and tissue damage.

Fourth degree: Irreversible cell death. The tissue is dead, and must be removed.

It’s common for the complete extent of the damage to take several months to become clear, and therefore the need for medical treatment extends beyond the initial care.

Treatment

The first assessment involves evaluation for hypothermia—pulse, respiratory rate, and blood pressure. Level of consciousness is next, and then the initial evaluation of the frostbitten areas, based on the degree of frostbite.

Treatment of hypothermia always takes priority. Save the person first, the extremities next.

Next is rewarming of the frostbitten areas, which can be quite uncomfortable (read: painful!) and require pain meds. IV fluids are commonly given as part of this process. Several methods can be used:

Warm water bath—most suitable for first and second degree frostbite. Remove clear blisters. In third degree frostbite, blood blisters are left undisturbed. Pink skin, return of feeling and motion are good signs. Observe for evidence of infection. Some practitioners give a tetanus booster.

External warming with heated blankets—suitable for any degree of frostbite.
Internal warming with warm fluids infused into the abdominal cavity—may be utilized in cases where hypothermia complicates the situation.
In critical cases where hypothermia is life-threatening, the most aggressive rewarming is done with a heart-lung bypass machine.
As with most injuries of this type, prevention is key.
Questions? Comments?

~*~

Kelly has worked in the medical field for over twenty years, mainly at large medical centers. With experience in a variety of settings, chances are Kelly may have seen it.

Sometimes truth seems stranger than fiction in medicine, but accurate medicine in fiction is fabulous.
Find Kelly’s fiction at www.kellywhitley.com.