Hypothermia

The armies of Napoleon were attacked by the hypothermia in tsarist Russia in their retreat in 1812.

Hypothermia (from the Greek hypo meaning "below" and therme meaning "heat") is the involuntary drop in body temperature below 35 °C (95 °F) as measured with a thermometer in the rectum or esophagus.

If the ambient temperature is very low, the body temperature drops sharply: a drop of just 2 °C (3.6 °F) can impede speech and the affected person begins to drowse. If the temperature drops further, the affected person may lose consciousness and even die.

Mild hypothermia is considered when the body temperature is between 33 °C and 35 °C (91.4 °F and 95 °F), and is accompanied by tremors, mental confusion, clumsiness of movements and trembling body.

Between 30 °C and 33 °C (86 °F and 91.4 °F) is considered moderate hypothermia and disorientation, stupor or drowsiness, and memory loss are added to the above symptoms.

Below 30 °C (86 °F) this is severe hypothermia, and involves loss of consciousness, dilated pupils, low blood pressure, and a very weak heartbeat and almost undetectable.

Causes

• Disease known as hypothyroidism.
• Alcohol poisoning (alcoholism) or drug addiction (heroin, barbiturates, ecstasy...).
• Exposure to an intense cold.

Electrocardiography

The characteristic electrical pattern of hypothermic syndrome is the Osborn wave.

Symptoms

Normal human body temperature is 98.6°F (37°C). Hypothermia can be divided into three stages based on severity.

• First phase:

In the first phase, the body temperature drops 1–2 °C (1.8–3.6 °F) below normal temperature (36 °C or 96.8 °F). Chills occur that can range from mild to strong. The victim is unable to perform complex tasks with his hands, the hands become numb. The distal blood vessels in the extremities constrict, decreasing heat loss to the outside through the air. Breathing becomes rapid and shallow.

Goosebumps appear and body hair stands on end, in an attempt to create an insulating layer of air throughout the body (of limited use in humans due to lack of sufficient hair, but useful in other species). Often the sufferer will experience a warm sensation, as if they have recovered, but they are actually heading towards Stage 2. Another test to see if the person is entering Stage 2 is that they are not able to touch their thumb with your little finger; It is the first symptom that the muscles no longer work. It is characterized by: vasoconstriction, increased metabolism, increased cardiac output, tachycardia, and tachypnea.

• Phase two:

In the 2nd phase, the body temperature drops by 2–4 °C (3.6–7.2 °F). The chills become more violent. The lack of coordination in the muscles becomes evident. Movements are slow and labored, accompanied by an irregular rhythm and mild confusion, despite the fact that the victim may appear alert. The surface of the blood vessels constricts more when the body focuses the rest of its resources on keeping vital organs warm. The victim turns pale. Lips, ears, fingers and toes may take on a bluish hue. Decreased cardiac output, bradycardia and bradypnea, polyuria, decreased intestinal motility, and pancreatitis.

• Third phase or Deep hypothermia:

In the 3rd phase (poikilothermic phase), the body temperature drops below about 32°C (89.6°F). The presence of chills usually disappears. Difficulty speaking, slow thinking, and amnesia begin to become apparent; The inability to use the hands and legs is also often present. Cellular metabolic processes are blocked. Below 86°F (30°C), exposed skin turns blue, muscle coordination becomes very poor, walking becomes nearly impossible, and the victim exhibits incoherent/irrational behavior, including hiding among things or even stupor. The pulse and respiratory rate decrease significantly, but rapid heart rhythms (ventricular tachycardia, atrial fibrillation) may appear. Major organs fail. Clinical death occurs. Due to decreased cell activity in stage 3 hypothermia, it takes longer than usual for brain death to occur.

In the US, the incidence of hypothermia is strongly related to age.

Prevention and treatment of hypothermia

Prevention

At -30 °C an ill-prepared person freezes in a minute, and it doesn't even take that much cold: the sensation and its effects multiply up to 14 times if there is humidity and 25 times faster in water than in air air. But the wind doesn't help either: you have to protect yourself from it not only with clothes, but with accidents in the environment that offer shelter or shelter. The subject must not sleep and must remain conscious, since the loss of consciousness due to hypothermia is gradual and is not perceived until one is dying. This is why freezing to death has been called the 'sweet death'. When the body cannot heat the entire body, it concentrates blood circulation in the trunk and vital organs (brain and heart), so these are the areas that should preferably be protected with hats, scarves, ear muffs, glasses, coats. Someone may not have a pulse in the wrist, but that does not indicate that he is dead from hypothermia: you have to take it in the neck, for what was previously stated. Other measures to take are:

• Protect and hide the exposed parts: the nose, ears, hands, feet are the most susceptible areas of freezing, although the protection of the head and the heart are fundamental.
• Dress up with three, four or more layers of clothes, the outside also waterproof. It is better the skin than the wool, because it warms inside, but makes sweat and this sweat soaks and freezes on the outside, making the wool a solid bark.
• Eating properly (many calories).
• Hydrate.
• Do not drink alcohol (which is a vasodilator and therefore helps to lose temperature).
• No smoking (has a similar effect on the lungs).
• Bring blankets to isolate from the cold soil; if there are no blankets, with something similar.

These measures are usually far from people with few resources (good clothing, good food, a well-insulated environment), which is why the homeless tend to be the most affected by hypothermia. When it's very cold, vital functions slow down and someone who may seem frozen to death may revive by regaining temperature. That is why it is often said among doctors that someone who dies from hypothermia is not until they are warm again.

Treatment

The main risk is that cold blood is transferred too quickly or abruptly from the periphery to the vital organs inside the body, causing further decrease in temperature, shock and death. This can happen if we make the victim move or move carelessly ourselves or if heat is actively applied (by friction or contact with a hot object): this activates circulation in the skin.

This is why the fight against hypothermia is essentially passive warming: the victim is placed in a warm environment and warms itself. Otherwise, she must be insulated (blanket) from the cold outside. In fact, if heat is actively brought in from the outside, adverse reactions are caused.

Famous cases of hypothermia

Napoleonic Wars

During the Napoleonic invasion of Russia, during the development of the Napoleonic wars, the arrival of the winter of 1812 caused thousands of French soldiers to die from hypothermia, this being the most important factor in the withdrawal of troops from Napoleon Bonaparte, who intended to invade the Russian Empire.

The Terra Nova Expedition

General Robert Falcón Scott and his research team died of hypothermia on their expedition to the South Pole in 1910.

Sinking of the Titanic

In the early morning of April 15, 1912, after the sinking of the British liner, many of the passengers aboard the Titanic, who survived until after the total sinking of the ship, were left floating in the ocean, dying of hypothermia, including many of those in the lifeboats.

World War II

During the course of World War II, especially on the Eastern Front, millions of people and hundreds of thousands of German and Soviet soldiers died from exposure to temperatures of -40 °C during the winter of 1941 and 1942 At the Siege of Stalingrad, at least one million people between soldiers and civilians died from starvation and hypothermia.

Mount Everest

Many specialists in mountain climbing dared to climb Everest, although many of them did not survive because of the low temperature in the highest parts of the mountain.