Saturday, January 30, 2010

Cold water shock survival

From Cottage Life, comes this article on the effects of cold water immersion on the body:
The lake’s November chill arches my back, pries my mouth open, forces my eyes wide until, overhead, I see the pewter sky through a cloud of bubbles. A second ago, I was up there, on the dock. Now I’m below the surface, flailing in liquid that feels as thick as gelatin, surprised by the water filling my mouth. A small voice, distant and oddly detached, muses: Am I going to drown?

The answer comes a second later, when my PFD delivers me, spluttering and gasping, back to the surface. Thank God, I think, still troubled by the underwater voice. Now I’ve got to last another 10 minutes, in a lake that’s nearly ice-water cold...

What is cold water shock?

A sledgehammer blow that can cause drowning, trigger heart failure, or chill victims so rapidly they’re unable to swim, hang on to a rope, or pull themselves to safety.

Cold water has been claiming lives as long as we’ve ventured near it, but it’s only during the past few decades that scientists have solved an ancient mystery: Why does cold water kill so quickly? How do strong swimmers succumb in seconds or minutes—long before hypothermia can set in?

The answer is the “huge, huge shock to the system” that comes with sudden, unexpected immersion in cold water, says Stephen Cheung, holder of the Canada Research Chair for Environmental Ergonomics. Known around St. Catharines’ Brock University as Dr. Freeze, Cheung is his own lab rat, dunking himself in chilled water while wearing nothing more than swim trunks. “People worry about falling in cold water and dying from hypothermia, but with cold shock, you’re not in the water long enough for that,” he says. “You die from drowning.”

So that’s why I’m a sodden and chilled guinea pig in Lake Muskoka. To help Cottage Life’s readers understand the threat that lurks off their docks and beneath their boats, my editor (in his warm, dry office) says, “We want show, not tell.” ...

Read the whole thing here. The article notes this important point about treating the cold water victim once he or she is out of the water:
The danger's not over once you're out

In one of the Second World War’s cruel medical mysteries, severely chilled sailors and airmen would routinely collapse and die after being plucked from the sea. Only after the war did researchers discover the victims were being killed with kindness. As rescuers tried to warm their charges, urging them to get up, sitting them next to the stove, plying them with soup or tea, they shifted cold blood from the extremities to the body’s core, chilling the heart, triggering a dramatic fall in blood pressure, and bringing on heart failure.

Anyone exposed to prolonged cold, or suffering from hypothermia, needs to be warmed slowly, under medical supervision. If paramedics aren’t yet on the scene, lay the victim in a plastic sheet and a blanket or sleeping bag, bundled up, and let shivering do the warming.

I spent almost as long lying on the dock in a sleeping bag as I did in the lake, but after eight minutes or so I was able to shuffle to the dive team’s heated truck and change into dry clothes. In another hour, with a couple of cups of coffee, I was over the immediate chill. By the next morning, after a good night’s sleep, I felt close to my pre-immersion self. [emphasis added]...

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