Anna Bågenholm froze to death under an icy lake in Norway, but she is now working as a radiologist: a competitive medical speciality. Why is she alive, and how is her brain still in such good condition?
Your brain is about 5% of your weight, but needs 20% of your blood supply to get enough oxygen to keep those neurons humming. If you turn off the taps, neurons die more quickly than other cells in your body. When we try to resuscitate someone, we care about “down time:” the gap between the heart stopping and chest compressions starting. Anna had forty minutes of down time before she was pulled from the water. In normal circumstances, ten minutes is enough to be sure of brain damage.
She was skiing after work with friends, lost control and crashed into a frozen lake. Her body cracked open the ice and the claws of water took hold of her, first drenching her clothes, then pulling her under as she struggled. Imagine the panic; then imagine the joy and hope when she found an air pocket sharing her prison under the ice, knowing her friends were just feet away. But they could not reach her and she lived gasping for forty minutes in this air pocket, an astonishing amount of time given the cold. Then she floated for another forty minutes dead to the damped cries of the shadows the other side of the ice.
Extreme cold is bad for us in several ways. If our fingers or toes get frozen through, their cells are fractured by ice forming inside them, and will never recover, as many frostbitten polar explorers and mountaineers will testify. Much more important is your core body temperature, and we have evolved mechanisms to guard this fiercely: involuntary shivering and instinct to search for shelter.
The exquisite balance of biochemistry in our bodies depends on all the conditions being right: the salinity, the acidity, and the temperature being near 37C (98.6°F). A few degrees either way, in fever or cold, enzymes – the nuts and bolts of life – stop working properly. Fever can be a helpful response to infection which helps the body clear an invader but the body never wants to let its core get cold. For example, blood clotting is reliant on a cascade of enzymes which do not work in the cold: if someone is bleeding cold after a car crash in the winter, then no amount of replacement blood can help them clot away their injuries. The regular swishes of chemicals and electricity through the heart with each beat are damped by cold, first noticeable on an ECG, then when the heart cannot pump enough blood to itself, it stops.
Anna was pulled from the lake about forty minutes after she died, with a core temperature of 13°C (57°F). Before her heart stopped beating, everything in her body would have slowed down, lessening each organ’s thirst for oxygen, and this was critical to her survival. She got chest compressions until the helicopter got to hospital, where she was warmed up. Her heart restarted and she woke up a few hours later. She did have major medical problems, and spent weeks in intensive care, but gradually things got better and she returned to work seven months later, with only a bit of nerve damage in her limbs.
Hypothermia is now becoming a standard technique for improving survival in cardiac arrest: yes, we chill people down for a few hours when they get to hospital.
Now for those who don’t do a lot of Nordic skiing: does being in the cold cause the common cold? There are several viruses which cause colds and they live in the slightly lower bodily temperatures in the nose and throat. In cold weather, the immune response of our upper airways gets worse as they get colder, but also the virus lives for longer in the cooler drier air of winter. So viruses are more likely to infect us in cold weather. We also behave differently in the winter, spending more time with other people behind closed windows, trapped with our sneezing friends and family, touching snotty bannisters and children’s toys. The traditional advice of avoiding cold may be right, but do wash your hands.
Thanks for the question, Simone DuPreez from South Africa: “Is being cold bad for a person?”