You Can’t Breath:
The first is phase of cold water immersion is called the cold shock response
: It is a stage of increased heart rate and blood pressure, uncontrolled gasping, and sometimes uncontrolled movement. Lasting anywhere from 30 seconds to a couple of minutes depending on a number of factors, the cold shock response can be deadly all by itself. In fact, of all the people who die in cold water, it is estimated that 20% die in the first two minutes.
They drown, they panic, they take on water in that first uncontrolled gasp, if they have heart problems – the cold shock may trigger a heart attack. Surviving this stage is about getting your breathing under control, realizing that the stage will pass, and staying calm.
You Can’t Swim:
One of the primary reasons given by recreational boaters when asked why they don’t wear a life jacket, is that they can swim. Listen up, Tarzan; I swam for a living for the better part of my adult life, and when the water is cold – none of us can swim for very long. The second stage of cold water immersion is called cold incapacitation. lacking adequate insulation your body will make its own. Long before your core temperature drops a degree, the veins in your extremities (those things you swim with) will constrict, you will lose your ability control your hands, and the muscles in your arms and legs will just flat out quit working well enough 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. Without ever experiencing a drop in core temperature (at all) over 50% of the people who die in cold water, die from drowning perpetuated by cold incapacitation.
You Last Longer than You Think:
If you have ever heard the phrase, “That water is so cold, you will die from hypothermia within ten minutes.” then you have been lied to about hypothermia. For that matter you can replace ten minutes with twenty, or thirty, or even an hour, and you’ve still been lied to. In most cases, in water of say 40 degrees (all variables to one side), it typically takes a full hour to approach unconsciousness from hypothermia, the third stage of cold water immersion. But remember, you must be wearing flotation to get this far.
We are all different in this regard, but I once spent an hour in 44 degree water wearing street clothes and my core temperature was only down by less than two degrees (I was not clinically hypothermic). It was uncomfortable to be sure, and I wouldn’t recommend finding your own limit, but it probably would have taken another hour to lose consciousness, and an hour after that to cool my core to the point of no return. The bodies efforts to keep the core warm – vasoconstriction and shivering – are surprisingly effective. The shivering and blood shunting to the core are so effective, that twenty minutes after jumping in (twice the “you’ll be dead in ten minutes” time), I had a fever of 100.2.
Out of the Water is Not Out of Trouble:
I lost count of the number of survivors I annoyed in the back of the helicopter because I wouldn’t let them move. I had a rule – if they came from a cold water environment – they laid down and stayed down until the doctors in the E.R. said they could stand. It didn’t matter to me how good they felt or how warm they thought they were. Because the final killer of cold water immersion is post-rescue collapse. Hypothermia does things besides making everything colder. Victims are physiologically different for awhile.