At what air temperature does a person freeze. Causes of death due to hypothermia

In the 21st century, the cold does not threaten our security in the same way as in past centuries. Frostbite and even more death from hypothermia are rare in the modern world. However, they are. In our time, mainly people in a state of intoxication, homeless people, as well as unlucky tourists and reckless climbers who neglect the basics of safety, die from the cold.

Strange as it may seem, but people endure cold in different ways, they are not equal in front of it. While some instantly weaken in the cold, others in the same situation feel like a fish in water. Where death is for a European, so for an Eskimo there is a comfortable coolness. The peoples inhabiting the territories beyond the Arctic Circle have acclimatized to the cold at the genetic level. They have increased cellular activity, like, for example, the monks from Tibet.

Tibet is a favorite destination for mountain climbers looking for extreme adventures. Every year arrogant climbers who have neglected their own safety freeze to death there. On the basis of one of such sad events, which was remembered as "The Tragedy on Chomolungma in May 1996", even several films were shot. Then, in time for a blizzard, five mountain climbers died from the cold on Everest, including the leaders of two mountain expeditions.

But, despite this, the Tibetan monks in the high mountain monasteries, sitting motionless in prayers, feel great. Although they can only rely on the warmth of blankets made of yak wool, which is thrown over the back, and tea with butter from yak milk. Scientists became interested in this phenomenon and found that the whole point is tummo - a form of meditation through which you can consciously increase your body temperature, influencing the thermostat of the hypothalamus, changing the pressure in the vessels and the activity of cells.

To a European, in order to freeze to death, it is not necessary to guard a herd of deer in severe frost. It is enough just to dress out of season and get caught, for example, in a storm somewhere on vacation in the mountains. Indeed, even a small positive temperature in combination with a strong wind and high humidity is not safe for a living organism. The fact is that even a light breeze with a speed not exceeding 20 kilometers per hour can aggravate the effect of low temperatures. This is the so-called "Wind-Cold" factor, the force with which gusts of air cool the body. The heat that a person generates envelops his body in a small insulating layer. But contact with wind, ice or snow destroys the insulation and precious heat is lost.

And in cold water because of its greater heat capacity, freezing occurs 25 times faster than in air of the same temperature! Death from hypothermia can occur in just 5-10 minutes. But this is only if the person did not die instantly in the ice hole from cardiac arrest as a result of spasm.


Let's briefly understand the physiological processes that occur in the body under the influence of low temperatures. This will help you better understand how to deal with hypothermia and will make it safer to stay in the cold.

A person has sensors throughout the body that send data about the ambient temperature to the hypothalamus. This part of the brain acts as a thermostat, giving out settings to warm certain parts of the body. As the body cools, stages of compensation and decompensation are distinguished in the process of regulating body temperature. In the initial stage, the body tries to defend itself and adapt to a drop in temperature. On the one hand, trying to reduce heat transfer, the body forms a so-called protective shell from the outer covers. Goose bumps appear. But gradually open areas of the body cool and turn pale, because blood flow decreases in them. The blood supply to the extremities is also reduced, concentrating in the head and trunkto provide blood and keep warm in vital organs - the brain, heart, lungs and liver. On the other hand, the body increases the production of heat within the body. Metabolism, blood pressure and muscle tone are enhanced. To keep warm, the person begins to shiver.

However, if the body continues to cool down, the stage of decompensation begins. For normal functioning, vital organs need a temperature of 35 degrees. Therefore, the closer the body temperature drops to this line, the worse it begins to function. With further cooling of the body, arms, legs, open areas of the body are completely sacrificed: their vessels narrow, blood flow to these parts of the body is reduced. And then the veins in the ankles and wrists close, stopping the circulation of blood in the arms and legs and redirecting the uncooled blood to the heart. Below this threshold, hypothermia occurs.

Hypothermia is a condition in which the internal temperature is too low to support the body's vital functions. In humans, hypothermia begins at 35 degrees and becomes severe at temperatures below 32 degrees. Brain functions slow down. Concentration and critical assessment of the situation is reduced. There is a desire to just fall asleep, and not fight for your life.

When stressed, the brain creates a protective barrier against aggression - a mixture of hormones released by neurons called monoamines. Monoamines are used in medicine as antidepressants. First, they help the body withstand the cold. But as soon as they stop working, the brain becomes lethargic. This is an entry into the phase below 35 degrees. The person is already constantly shaking. Freezing in the stage of no return - at 31 degrees, when hallucinations begin, and the trembling stops. Confusion of consciousness is a sign of deep hypothermia, followed by a coma soon. In this state, the border between consciousness, insanity and death is invisible.

People affected by hypothermia become as fragile as glass. One wrong move can lead to heart failure. If warmed gently, they can recover without consequences.

Frostbite is another destructive cold weapon... The leg, arm, and even the entire limb can become numb and numb. When blood stops flowing into tissues, ice crystals form in the cells, seriously damaging them. In such cases, the cells literally explode under the influence of cold.

If you find yourself in a situation where there is even the slightest risk of freezing to death or freezing body parts, take action immediately. There were frequent cases when people were found dead from hypothermia and at the same time they had supplies of food and warm clothes that they did not use to save themselves. And frostbite as a result of neglect of the simplest security measures in general can not be counted. So:

1. Make the most of all your equipment. All clothes that you have on hand should be on you! If you have a hood, you need to put it on your head. The entire length of the scarf is used to warm the face, neck and chest. Buttons, buttons, ties - all these little things that people in everyday life forget about and don't use, everything should work to save precious heat. Remember, the thicker the clothing and the less exposed to wind and cold, the better the insulating layer.

2. The next thing you should take care of is shelter from the wind... Ideally, it would be nice to wait out the bad weather in a cozy forest house by the burning fireplace. But fate will not always please us. Therefore, even a stone, a thick tree trunk, a depression in the snow, if they can protect themselves from gusts of wind blowing through and through, are suitable for temporary shelter.

3. What should not be forgotten in such a situation is movement. Need to stay activeto generate heat. Move your fingers and toes constantly, directing warm blood towards them.

4. Need constantly watch for signs of frostbite... Moreover, it is necessary to constantly monitor the degree of cooling of the body.

5. If there is food, do not miss the opportunity to use it. The heat effect of nutrition has a double effect... Digestion creates calories first, and then nutrients restore metabolism.

6. When plus or minus a few degrees, plus or minus a few calories can swing the pendulum of life and death, the psychological aspect plays an important role. Family and children, important unfinished business - thinking about this can help in the struggle for life.


7. Alcohol in the cold is not an additional source of heat, but an additional source of threat to human life! First, a drunk person becomes less careful. Not realizing the danger, he can lie on the snow, unbutton his clothes, and sometimes even undress. Secondly, strong drinks, taken internally, reduce the body's metabolism and oxygen consumption by the tissues, thereby reducing the production of heat in the body. The stronger the drink and the more drunk, the stronger alcohol lowers the body temperature.

8. It should also be remembered that children and sick, physically weakened people are much more susceptible to the effects of cold than a healthy person.

How can you help people who have become victims of the cold?
A person who has suffered from low temperatures should first of all arrange for medical assistance. But if specialists are still on the way, you should not waste precious minutes, and you can also help a person in the struggle for life. The main thing that the victim needs in such a situation is active warming.... If possible, the person should be moved to a warm room or to another heat source, such as a fire. If this is not possible, then try to cover the freezing person with clothes, a blanket, and give hot sweet tea.

If the victim has mild frostbite of a part of the body, then it must be warmed, for example, by hiding the injured hand under his own jacket. With a strong degree of frostbite, do not touch the affected areas.

Massage or rubbing with snow is contraindicated in such situations!

Do not be indifferent and do not pass by a drunk person who is asleep or sitting in the cold (even in "positive weather"!). Drunk people are the main victims of low temperatures. If you are unable to take him to a warm room, ask the relative's phone number, call him and report the incident. In extreme cases, you can call the police or an ambulance. Your concern will help save a person's health or even life.

And finally, I would like to recall the history of the American climber Francis Arsentieva. For the sake of the record of an oxygen-free ascent to Chomolungma, already on the descent from the mountain, she sat exhausted for two days and died of the cold. Mountain climbers from different countries passed by the freezing but not yet dead climber. Someone offered the woman oxygen, which at first she refused, thereby cutting off the last chances of saving her life. Francis just didn't want to ruin her record. Later, people were found who tried to gather a group in order to remove her exhausted body from a height. But they too soon left, because their further stay at the height and in the cold threatened their safety. There is only one conclusion from this sad story: not a single chance for your salvation should be missed, because life and health are dearer than any awards and achievements.

Every year, mine rescuers around the world have to rescue those caught by an unexpected storm, buried under avalanches, lost, and also immobilized by frostbite in the wrong selection of clothes.

Most of those affected are fully exposed to the cold.

The most ancient victim of hypothermia can probably be called Ötzi, a shepherd who died more than 5200 years ago in the Ötztal Valley, located high in the Alps between Austria and Italy. His mummified body was found in 1991 by tourists - half thawed out of ice at the edge of a glacier. Oetzi was dressed quite well for crossing the snow - a straw raincoat, leather leggings, a fur hat and a jacket. However, three broken ribs and a lack of supplies suggest that he left home in a hurry, survived an attack on the way, and was then caught in the cold.

The normal internal temperature of the human body (the temperature of the deep tissues of the chest and abdominal cavity) is 36-38 ° C. Hypothermia is classified in medicine as a drop in this temperature below 35 ° C. Its symptoms change as the temperature decreases.

With slight hypothermia, trembling occurs, hands do not obey, motor skills deteriorate. Difficult actions - for example, skiing down, cause difficulties, a person feels tired, cold, becomes hot-tempered and intractable. Mild hypothermia is difficult to identify, especially since the victim himself actively denies it. However, it can be dangerous. Failure to button a jacket or wear gloves leads to further hypothermia and frostbite. A drop in the internal temperature, even by one degree, slows down the reaction and can interfere with an adequate assessment of the situation - for example, slight hypothermia often leads to accidents on the road. This is especially true for motorcyclists who freeze during long winter runs and market traders who drive in the cold all day.

Moderate hypothermia occurs when the internal temperature drops below 35 ° C. It is characterized by severe tremors, deterioration of fine motor skills and coordination, so a person moves slowly, with difficulty, often stumbles and may fall. Mental abilities also suffer. Speech becomes indistinct, thought processes slow down, decisions are made inappropriate. I want to lie down in the snow and fall asleep, throw off a too heavy backpack, or even start undressing, since the cold is not felt. Climbers can incorrectly fasten the belay, which also leads to tragic consequences. Victims of hypothermia become apathetic, lethargic, immersed in themselves, do not make contact and answer questions inappropriately. They often cannot remember recent events.

As soon as the internal temperature drops below 32 ° C, the trembling stops, since the body's energy has already been depleted by that time. After that, the temperature drops more rapidly, because the muscles no longer produce heat. In the end, a person can no longer walk and, in a semi-conscious state, curls up in a ball in the snow, forgetting about the rest. Consciousness is lost somewhere at 30 ° C. As one of the victims later said: “I felt colder and colder. The face froze. Hands were freezing. I did not feel my body, and then it became completely impossible to concentrate and I just fell into unconsciousness. "

With deep hypothermia, the heart rate slows down, the pulse becomes threadlike, breathing is superficial and chaotic, elusive. The respiration rate drops to one to two breaths per minute, and the same happens with the heartbeat. The skin turns pale and becomes icy to the touch, the limbs do not bend, the pupils dilate and do not react to light. The person looks like dead, although in fact he may still be alive. This condition is sometimes called the "metabolic freezer" because life processes slow down, as if in deep suspended animation.

The heart rate slows down because cold depresses the heart. When the internal temperature falls below 28 ° C, cardiac arrhythmia may occur, the most dangerous type of which is ventricular fibrillation - irregular convulsions of the heart muscle that prevent normal blood pumping and lead to death. However, even without flickering, if the inner the temperature will drop up to 20 ° C, the heart will stop.

Today it is impossible to say which death is more painful: from overheating or hypothermia. But in the 21st century, these cases seem so terrible that it is difficult for us to believe that a person voluntarily found himself in extreme conditions and then died.

Yet more often they die of cold. And it is the low temperatures that are most destructive for the human body.


So how does a person die of cold

Is it a quick death or a painfully long one? How much does a person who does not have the opportunity to warm up suffer?

Modern science already has answers to these questions, and here are several stages of dying from hypothermia:

When the body reaches temperature 36 degrees in the neck and shoulders of a person, muscles begin to involuntarily tense and this is the first alarm signal, after which aches appear in the arms and legs. Blood is draining from the capillaries of the limbs and you feel intense cold.


About an hour passes and a chill appears, turning into severe convulsions - the body, having cooled down to 35 degreestrying to keep warm on her own. Muscles contract, but this does not in any way affect the decrease in the metabolic rate - it continues to fall in proportion to heat loss.


However, the really terrible consequences of hypothermia begin to manifest themselves only when the body reaches a temperature of 34 degrees.

Brain activity is impaired, a person begins to lose memory and already at this stage cannot help himself on his own.

Where is he, what is happening to him - the person is no longer able to answer these questions.


And at the turn of 30 degrees blood thickens. At the same time, the kidneys are trying to remove more unnecessary fluid from the body. The freezing one finally ceases to dull what is happening around: the person does not recognize anyone, because of the lack of oxygen in the blood, he sees hallucinations.

Then the rhythm of the heart is disrupted, and at the border of the body temperature of 29 degrees, a person can calmly die from hypothermia.

And yet, lingering on the brink of death, a person in this state can spend up to several hours.

This is easily explained. At extremely low temperatures, the body does not die immediately. It seems to be canned and barely shows signs of life. All processes in it are slowed down to the limit and therefore a frozen but living person can be easily mistaken for a corpse.

It should be noted that in such a situation, the victim can still be saved, but this must be done carefully and gradually.


What else is wonderful about death from cold

Sometimes people who are frozen to death are found completely naked, and then the criminologists have a plausible version of the robbery, but this is not so. The fact is that at the extreme moment of hypothermia (about 29 degrees), a person begins to feel heat.

This happens because the muscles that compress the peripheral vessels and prevent the flow of blood to the outer integuments of the body, for lack of nutrition, relax and some part of the warm blood from the internal organs rushes into them. Then, in unconsciousness, a person begins to tear off his clothes, thereby bringing his death closer.

Another paradoxical phenomenon often accompanies excruciating death from hypothermia. Just before the end and in a state of almost insanity, the dying (probably following their deep animal instincts) try to hide from the cold behind a closet or under a bed.

Scientists explain this by the similarity of the behavior of a freezing person with the behavior of hibernating animals, and is called Terminal Digging. So a bear or badger, before hibernation, is first buried in a hole or under a layer of foliage and branches.

Causes

The pathogenesis of cold injury has been of interest to researchers for many decades.

Currently, experts define cold injury as a complex process of interaction between damaging factors and the body, the result of which is the development of hypothermia.

Hypothermia is divided into the following types:

  1. Random.
  2. Primary.
  3. Secondary.

Accidental hypothermia is said if the injured person was in bad weather ( low temperature environment, high humidity, strong wind) or under normal conditions, but in a stationary or limited mobile state, in clothes and shoes that do not correspond to the season, in a state of overwork. It is this variant of hypothermia that is described in most manuals as general hypothermia.

Primary hypothermia is called hypothermia, which occurs when the thermoregulation center located in the hypothalamus is damaged. Secondary hypothermia develops in patients with endocrine and neurological pathologies, exhaustion, and alcohol intoxication.

The cause of death due to hypothermia is the effect of low temperature on the body. A kind of "chain reaction" of pathological changes is provoked, ultimately leading to the cessation of vital activity. The researchers note that morphostructural transformations in organs are largely due to circulatory disorders.

The differences in the influence of "fast" and "slow" types of hypothermia on carbohydrate metabolism have been clarified. In the first case, only the level of glucose in the blood changes (its concentration drops sharply). In the second, glucose disappears, and glycogen reserves are also depleted.

To confirm the hypothesis of cold death, all other possible causes must be excluded.

The signs that characterize death from cold are usually classified as visible (external) and internal. The first group includes:

  • a special position of the body, or the pose of a "chilly person";
  • "goose pimples";
  • "Frosty erythema";
  • the sign of Paradise;
  • frostbite;
  • chills.

The "chilly person" pose is a position in which the victim "curls up", pressing against chest arms bent at the elbow joints and pulling the knees to the stomach. It should be noted that this sign is not always observed: it is absent if the person was forced to be motionless, fell asleep in a state of alcoholic intoxication, or was so tired that he fell facedown with outstretched arms. The pose of the "chilly person" indicates that the victim for some time before his death was in a clear consciousness and controlled the movements of his body.

"Goose bumps" is a sign of a lifetime in the cold. Its occurrence is due to the contraction of the muscles that raise the hair. The symptom is a subject of debate among forensic doctors, as it is assumed that goose bumps can occur not only in persons subjected to cold injury. There is also controversy about "frosty erythema" - pink-red and purple spots that are located on the face and limbs.

Paradise sign (the appearance of ice or icicles around the mouth, nose, eyes) is caused by the freezing of nasal mucus and tears. This symptom indicates that the person who is freezing was breathing. Fixation of the Paradise sign must be carried out during the initial examination, since it is lost during transportation.

Some authors consider the presence of frostbites on the body as an indisputable sign of death from hypothermia. Frostbite can be seen on the protruding parts of the face, limbs (fingers are most often affected).

Chills occur in conditions of high humidity in combination with low temperatures, it is characterized as inflammation of the skin that develops without the participation of infectious agents. Sometimes chills are considered as an option for frostbite. Objectively, you can observe reddish-cyanotic or purple spots against the background of edematous, tense skin. Chills are usually found on areas of the skin that are not protected from external influences.

Additional and internal signs

Several additional features that characterize the appearance of a person who died from the cold should be named:

  • swelling of the glans penis, acquiring a bright red color;
  • tight compression of the mouth (closing the lips);
  • slow development and reddish tinge of cadaveric spots;
  • slow development and long-term preservation of rigor mortis;
  • prolonged absence of signs of rotting of the corpse.

Among the internal signs, one can name pathomorphological changes in the lungs, heart, liver, as well as hemorrhages on the gastric mucosa, called Vishnevsky spots. Microscopic examination reveals edema of myocytes of the muscular membrane of the stomach wall, the acquisition of a burgundy color by hepatocytes, delipidization of the adrenal cortex.

For differential diagnosis various pathological conditions and cold death assess the glycogen content in the liver, heart and skeletal muscles. With hypothermia, there is a significant decrease in the amount of glycogen; sometimes it is not possible to detect its presence at all.

The combination of external and internal signs of death from hypothermia of the body makes it possible to establish the reliability of the lifetime effect of low temperature, its significance in the disruption of vital processes.