Hypothermia happens when the body loses heat faster than it can be produced. Normal body temperature is 98.6 °F. Below 95 °F is considered hypothermia. Organs, body functions and systems slow down — breathing, the heart, the nervous system, for instance — which can lead to heart failure and death.
According to the CDC, from 1999 to 2011, each year an average of 1,301 people died because of hypothermia. Most of the time, people get in trouble when they are exposed to cold weather or cold water. Sometimes it happens in the supposed safety of a person’s home. The older you are, the higher your risk, which I wrote about in another blog post.
Cold water and hypothermia
If a person is exposed to cold water, hypothermia usually develops more quickly. That’s because body heat is lost about 25 times faster in cold water than in cold air. From the moment you hit the water, the body begins to react, but hypothermia is not the first thing that happens.
Mario Vittone is considered a “leading expert on immersion hypothermia, drowning, sea survival and safety at sea.” According to his website, he oversees the development of safety and security training products. In his article The Truth About Cold Water, he outlined what happens when someone is immersed in under 50° water. I’ll list some of his main points in this blog post.(You can read the entire article here.)
Vittone says these responses almost always happen in this order.
You can’t breathe
When you first hit the water, you get what is called a cold shock response. It can last from 30 seconds to a couple of minutes. Think of diving into the lake or the ocean on a warm spring day in Maine, where the water is always cold.
Vittone estimates that 20 percent of people die in the first two minutes. Not because of hypothermia, but because of drowning. They panic and swallow water or the shock triggers a heart attack. He writes: “Surviving this stage is about getting your breathing under control, realizing that the state will pass, and staying calm.”
You can’t swim
Your body becomes incapacitated by the cold. The veins in your arms and legs constrict and the muscles stop working as they should. You need to have something to keep you above water. “Without some form of flotation, and in not more than 30 minutes, the best swimmer among us will drown — definitely — no way around it,” says Vittone.
You last longer than you think
“In most cases,” says Vittone, “in water of say 40 degrees (all variables to one side), it typically takes a full hour to approach unconsciousness from hypothermia, the third state of cold water immersion.”
But you need to have something holding your head above water, he emphasizes.
Out of water is not out of trouble
When you pull someone from cold water, even if he/she says they’re fine, it’s important to be warmed up before walking or moving around. Some people die because of post-rescue collapse. Hypothermia doesn’t just make everything colder, says Vittone. For one thing, the heart stops working up to speed. “Getting up and moving around requires your heart to pump more blood,” he says. “Being upright and out of the water is also taxing, then any number of factors collide and the heart starts to flutter instead of pump — and down you go.”
If you want to know what to do if someone accidentally falls into cold water, read Vittone’s follow-up article The Truth About Cold Water Recovery.
And wherever you are, please be safe this summer.