Brown urine, loose teeth... How to explain the symptoms of the survivors of “Snow Circle”, on Netflix?

Temperatures reaching -30°C at night, a piece of cabin to shelter from the frozen wind, avalanches, meager food reserves quickly exhausted... For more than two months, this hostile environment made snow and rocks was the only horizon for the survivors of Fuerza Aérea Uruguaya flight 571, which crashed on October 12, 1972 in the Andes, between Chile and Argentina. The film “Le Cercle des neiges”, on Netflix, tells the drama experienced at 3,600 meters of altitude by the rugby union team which took place there. Of the 45 passengers and crew members, only 16 survived until help arrived on December 22 and 23 of the same year, forced to eat the flesh of their companions in misfortune to survive. How can the human organism survive in these conditions of cold and extreme isolation, and how can we explain the symptoms that affected them?

Frostbite is an allergic reaction of the skin to cold, which usually affects the areas located on the extremities (fingers, toes, nose and cheeks). First, they become red and itchy. “This reaction is generally observed in people who work in the mountains such as ski instructors,” reports Dr. François Lecoq-Jammes, general practitioner, specialized in isolated environment medicine (emergency, mountain, travel, sport), and chef of the emergency and mountain medicine center at the Institute of Training and Research in Mountain Medicine (Ifremmont). Frostbite is caused by a reduction in blood supply to the most external parts of the body: to conserve internal heat, the body reduces the diameter of the arteries of peripheral organs (such as the nose or fingers), for the benefit of the organs internal.

If the cold is intense and endured for a long time, water crystals can form in the tissues most exposed to the cold. This frostbite manifests itself as a dark blue to black color, following necrosis (death) of the affected tissues. As frozen water crystallizes, it destroys blood vessels and surrounding cells. “The crystals destroy the cells, and when the body is heated, the affected tissues are dead and must be removed to avoid septicemia,” explains Dr. Lecoq-Jammes. Frostbite can therefore lead to the loss of a finger, toe or nose.

In the film, the survivors end up having brown urine. This phenomenon is primarily linked to dehydration. The survivors were certainly surrounded by snow and used it to hydrate themselves. Without this, they would not have survived: it is estimated that an organism cannot survive beyond 100 hours without drinking, because waste accumulates in the blood and kidneys, without being able to be eliminated through urine. But apart from the difficulties they may have encountered in melting it and drinking in sufficient quantities, the snow water is in any case almost entirely demineralized, devoid of essential minerals such as calcium, magnesium or sodium. Drinking water deprived of minerals modifies the water and mineral balance of the body, which is then deficient in minerals. Destabilized, the body produces hyperconcentrated urine.

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At 3600 meters above sea level, you can come across some mosses and lichens, possibly rare birds. But nothing around the wreckage of the plane allowed the survivors to eat. It is estimated that a man can go 70 days without food if he has sufficient water intake, but the body weakens quickly, especially when subjected to extreme temperatures. Once the few meager foodstuffs found in the passengers' suitcases were exhausted, the survivors ended up resolving to eat the bodies of the dead around them. “These actions were imposed and are logical in relation to their living conditions at the top of the Andes. They did what they had to do to survive,” explains Dr François Lecoq-Jammes. They were not condemned for this once saved.

The survivors were therefore only able to consume meat. Whatever it is, is it enough? The Inuit diet, mainly meat with some fruits and vegetables, shows that this diet is sustainable for the human body. But if a very small quantity of plants is enough to provide the body with the quantity of vitamin C that the human body needs, when we are completely deprived of it, as the survivors were, we quickly find ourselves deficient. When it is severe, we develop scurvy. This extreme lack of vitamin C induces abnormalities in the structure of collagen, with hemorrhages, healing disorders, immune weakness, poor absorption of iron. Among other symptoms, the gums become red and swollen, then bleed, the teeth become loose, then become loose. In the film, we see one of the survivors notice that the teeth of one of his companions are moving. We also see that they suffer from significant wounds, particularly on the back, undoubtedly favored by the prolonged lying position and the healing difficulties linked to scurvy.

Also read: Extreme cold: the main risks for the human body

There are 3 main zones of the body's reaction to cold depending on the temperature felt by the human body: between -20 and -25°C, we consider that a properly dressed person can carry out their daily activities; between -25 and -50°C, you must be dressed with adequate protection for extreme cold and move around to generate more body temperature; below -50°C, the temperature becomes dangerous.

The survivors were exposed to a minimum of -30°C at night, but the wind accentuated the feeling of cold; for example an outside temperature of -30°C associated with a wind of 60 km/h returns a felt temperature of -50°C. In addition, the survivors were not dressed appropriately to withstand these extreme conditions, particularly at night. “What is dangerous is the loss of temperature. The human body produces heat, when we produce a movement 20% of the energy released is thermal. Those who were immobilized died of cold, those who moved had a metabolism allowing them to maintain a constant temperature,” analyzes Dr François Lecoq-Jammes. Accumulating layers of clothing found in suitcases, huddling together at night and trying to block the wind vents in the cabin that sheltered them as best they could, allowed the survivors to survive despite everything. During the day, however, the sun and physical activity made the temperatures more acceptable, as evidenced by the photos taken by the team, some of whose members are shirtless.

Some people are more willing to survive in these extreme conditions. “It’s about the weight-to-height ratio; if people are fat, they will better resist exposure to winds and cold, explains Dr François Lecoq-Jammes. The more reserves we have, the longer we will be able to hold out.” Individual resistance to the cold will therefore depend on a set of factors such as the presence of fats, an effective textile covering and a location little exposed to the wind. The survivors were young and athletic. A strong mind probably also allowed them to overcome the challenges. “The survivors were subjected to extreme conditions of hunger and cold. Rugby is a team sport of cohesion, we can think that team spirit allowed them to endure these conditions thanks to psychological qualities,” explains Dr François Lecoq-Jammes.

Did the survivors suffer from altitude sickness? The higher we go, the more oxygen (O2) becomes rarer, but it is essential for the functioning of our body. “When oxygen is less available, it is hypoxia, the body functions less well,” reports Doctor François Lecoq-Jammes. However, "the body acclimatizes to altitudes below 5,000 meters where it is possible to live." In the first moments, the body increases its pulmonary and heart rates. After a few days, more of the hormone EPO (erythropoietin) is produced, leading to an increase in the level of red blood cells in the blood and making it thicker. This allows for better capture of atmospheric O2.

Altitude can also lead to the formation of edema, usually localized on the hands and face. These edemas are dangerous when they form in the lungs or the brain, especially associated with dehydration. They usually disappear after 24 to 48 hours at altitude, but brain edema can lead to bouts of dementia, leading for example to a mountaineer undressing thinking he is extremely hot, even though the temperature outside is negative!