Re: [Paddlewise] Cold Water Gasp

Chuck Holtz wrote:

  In those cases where people have gasped underwater and inhaled water, I 
>  suggest that surprise may have been as big a factor as water temperature. 
In 
> 
>  situations where the person is mentally prepared, I suggest that an 
>  underwater gasp is rare or nonexistent. By mental preparation, I mean that 
>  the person has chosen to immerse himself or herself in cold water, or is 
>  accustomed to it. 

and Matt:

>>It is my understanding that the folks most likely to be affected by cold
water shock mare those whose torsos are exposed enough to experience a very
sudden decrease in skin temperature there and those who may have lost their
ability to control the gasp reflex when underwater due to the effects of
drinking alcohol on the nervous system. I'm guessing alcohol's effect of
dilating the blood vessels near the skin might also increase the magnitude
of the "shock" experienced during cold water shock.<<


In Wayne Horodowich's new and very excellent videos on Kayak re-entries and 
rescues (http://www.useakayak.org/) there is a segment of video shot during 
testing of cold water effects.  A trained and experienced Navy(?) diver, 
dressed in a swim suit and breathing through a typical diving mouthpiece, is 
strapped in a chair.  He is slowly lowered into water at (IFIRC) 50 F.  He 
looks calm and collected until the water hits his head, then he starts 
gasping uncontrollably in the mouthpiece.  I'm sure he was mentally prepared. 
 What he wasn't was dressed for immersion.  The effect is real, and deadly -- 
just not universal.

Harold
---------------------

I believe that is the same clip that we use in our Cold Water 
Workshops. It is a British tape and the man is a trained diver. He is 
instrumented to record breathing,  heart rate, and (probably) blood 
pressure. His head is not submerged. I believe the receptors involved 
with the response are in the torso area. I think the gasping reflex 
is not induced just by submerging the head in cold water. 

The point of the film clip is to demonstrate the gasping, which 
continues uncontrolled for a time while the diver is swimming, but 
also to show that as he swims he looses control of the movements of 
his arms and legs. Thus, over some minutes in the 50 degree F water, 
the diver looses the ability to swim. In your average boating 
accident, with the victim in street clothes, gasping for air and soon 
unable to swim, drowning occurs long before death due to hypothermia 
occurs.

That is my message, and it is not avoided by a prepared mind. A few 
people survive better or longer, but it is not right to lead the 
public to believe that if they just have their heads right they will 
survive.

The man in the photo exhibiting the gasp response is standing on the 
bottom and can stand up after dunking. It is not by accident that his 
demonstration is carried out where he can get his head back above the 
surface.

Thanks,
Chuck Sutherland
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