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Robert Wolov <wolov@hi*.co*> wrote:
>As far as divers are concerned (assuming those with with very small 
>defects), there is the possibility that gas bubbles on the venous side of 
>the house, instead of getting trapped in the lungs, could get across this 
>open hole to the left side and get sent to the brain and other organs 
>(not a good thing) if the pressure on the right is raised, say by trying 
>to clear your ears doing a Valsalva maneuver.

Years ago I went on some chamber runs (as part of a diver education
program), and I still remember good old Jules Fortin (one of the pillars
of the Canadian Navy underwater program) saying as our bottom time was up
and he was about to start turning valves "Going up ...  and NO
VALSALVA!".  The impression I got at the time was that this would be
because it wouldn't be smart to do something to increase your internal
pressure at a time when external pressure was decreasing, and embolisms
were what was feared, but would this perhaps also help avoid PFO shunts? 

I've always since then employed Valsalva strictly for descent only, FWIW.

-- 
Anthony DeBoer                                  http://www.onramp.ca/~adb/
adb@he*.re*.or* (here)
adb@ge*.co* (work)                             #include "std.disclaimer"

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