PFD can help a victim survive ice-water plunge.

Byline: Susan Palmer/The Register-Guard

Falling suddenly into cold water isn't like a surprise tumble into the popular community swimming pool.

Immersion in Oregon's chilly rivers and the Pacific Ocean, which average 50 to 60 degrees in the summer, shocks the body in a way that researchers have documented but that few boaters understand.

Known as cold water immersion, it's characterized by three stages, said Gordon Giesbrecht, a professor at the University of Manitoba's Laboratory for Exercise and Environmental Medicine. For 20 years, Giesbrecht has studied how the body reacts to cold.

The bad news: You can die quickly. The good news: A life vest can keep you alive up to an hour, even in ice-cold water.

"Most people, including medical people, think you'll become hypothermic in ice water in a couple of minutes. If people think they're going to die quickly, it becomes a self-fulfilling prophesy," he said.

Here's what happens: A plunge into cold water immediately provokes a gasping and hyperventilating response by the body, followed by decreasing muscle and nerve control and the eventual onset of hypothermia. Death can occur at any of the three stages, but if a person survives the first two, he has an hour or more to be rescued.

Initial gasping and hyperventilating can last anywhere from 10 to 60 seconds, Giesbrecht said.

"You fall in, you take that gasp. If your head is underwater you'll drown immediately," he said. If your head is above water, it takes a while to regain breath control.

"The dangerous part is if you start to panic, you just keep feeding that hyperventilating indefinitely and that can lead to fainting," he said. "You can get yourself into real trouble."

The initial shock of cold water also can cause a heart attack.

If a victim survives the first stage, the body begins to route blood away from arms and legs to maintain heat in the central body core. Giesbrecht estimates there is about 10 minutes of meaningful physical activity before the muscles stop functioning. Then, hands can no longer grasp a rope or fasten a buckle.

After that, victims have about an hour before hypothermia renders them unconscious.

"There's a whole lot of time before you die," he said.

To help boaters remember the sequence, Giesbrecht has come up with a simple reminder - the 1-10-1 strategy. That's a minute to stabilize breathing, 10 minutes of physical activity and an hour before hypothermia sets in. The times are based on a body's reactions in ice water. In Oregon's coastal waters, victims could expect to survive several hours, he said.

Wearing a life vest keeps your head above water while you're gasping and trying to get control of your breathing. It continues to support you during the 10 minutes when you are physically capable of swimming or pulling yourself out of the water. And it continues to buoy you when you've lost the ability to support yourself in the water. The cumbersome, self-righting Type I life vests will hold your head above water, even when you do become unconscious.

But they need to be worn in order to work, and putting them on after you've fallen into the water is extremely difficult, Giesbrecht said.

"If you have a life jacket on, whether you can swim or not, you're not going to drown. The most important thing when you fall in is to get your breathing under control. That stems the panic, and gets your mind clear so you can start making good decisions," he said.

This information is slowly trickling out to the public. Outside Magazine interviewed Giesbrecht on the topic in 2003, and he's created videos that have appeared on the Discovery Canada cable TV channel. He has been a guest on David Letterman's TV show, and he has a book coming out in October.

"It's frustrating, but we are starting to see some change and increasing awareness," Giesbrecht said.

For more information on his research, visit www.umanitoba.ca/physed/giesbrecht.

WHICH BOATERS WEAR LIFE VESTS?

Runabout, speedboat: 4.5 percent Cabin cruiser: 2 percent Pontoon: 2.9 percent Cabin sailboat: 11.1 percent Inflatable raft: 45 percent Canoe: 28.8 percent Kayak: 84.1 percent Source - 2003 U.S. Coast Guard study

OREGON RECREATIONAL BOATING ACCIDENTS*

2003: 197,591 registered boats, 74 accidents, 18 fatalities; 14 victims did not wear life vests

2004: 190,412 registered boats, 52 accidents, 9 fatalities; 6 victims did not wear life vests

2005: 187,640 registered boats, 54 accidents, 15 fatalities; 7 victims did not wear life vests

Source - Oregon State Marine Board.

*Recreational boating accidents only. The state doesn't track charter boat accidents.