English is an imprecise language - you have to know the context of
everything for it to make sense. However, the analogy of a railroad switch
is perfect. Before we are born, there is a flap between the right atria and
the left atria of the heart. Since we are not breathing, our lungs are full
of fluid, and we get our oxygen from the placenta interface - no need to
breath, no need for the heart to send blood through the lungs and back, so
it "shunts" the blood across between the two atria. The normal path is for
venous blood to enter the right heart , be pumped through the lungs, and
then back to the left heart where it is pushed into the arterial side.

So you see that 100% of us have this flap. In 70% of us this flap grows back
to the left atrial wall. In 30% of us there is some unattached part, but the
flap generally stays shut since there is no pressure differential to open
it. If it does open, it allows blood from the right side to pass to the left
side without going through the lungs. If it were wide open, the person would
always be short of breath due to lack of enough oxygenated blood making it
into the arterial side. In a diver, this means that blood containing bubbles
from the venous side does not get filtered by the lungs and the bubbles get
shot straight to the arterial side, and the body parts supplied first are
the brain, spine and heart - not good places for bubbles.

Things like coughing or urinating can change the pressure differential , and
the manipulations to the body by the doctors doing PFO tests are an effort
to simulate this, but the big factor is this: if you generate enough bubbles
they will inhibit the passage of blood through the lungs and raise the
pressure between the right heart and the lungs, causing a differential that
can then push open the flap and let blood "shunt" over to the left atria.

This is important information and needs to be made available to all, not
hidden, twisted, or obscured by DAN or other dive industry shills.

-----Original Message-----
From: Jonas Bergenudd [mailto:jonas@be*.ne*]
Sent: Wednesday, June 06, 2001 5:47 AM
To: Trey
Subject: RE: MINIMUM DECOMPRESSION


Hi George

OK, it's a medical term.

I thought it was some slang for something. Like stroke.

I have a pretty good grasp of english but when it comes to specialized
english my limtations show. English is my second language.

My dictionary said that a shunt is a railroadswitch. (didn't help much :o)

regards
Jonas

--
Jonas Bergenudd
+46 733 909 909

> -----Original Message-----
> From: Trey [mailto:trey@ne*.co*]
> Sent: Monday, June 04, 2001 1:57 AM
> To: Jonas Bergenudd; Quest@Gu*. Com
> Subject: RE: MINIMUM DECOMPRESSION
>
>
>
> Sorry, should have been a "c" . Come on, cardiac and pulmonary shunts are
> not an American thing, they are a God thing. We all have them
> until we take
> our first breath, and then in 70% of us they heal up. In 30% they
> do not to
> some degree, and can be opened by a choke of bubbles in the lungs causing
> the right side heart pressure to rise above the left, allowing the Patent
> Foremen Ovale to open , letting unfiltered blood cross over to
> the arterial
> delivery side resulting in paradoxical gas embolism, usually CAGE and or
> spinal.
>
> -----Original Message-----
> From: Jonas Bergenudd [mailto:jonas@be*.ne*]
> Sent: Sunday, June 03, 2001 6:27 PM
> To: Quest@Gu*. Com
> Subject: RE: MINIMUM DECOMPRESSION
>
>
>
> >   On gassing is easy - you do not blow gas into the tissues in
> bubble form
> > by on gassing. Off gassing is more tricky, as you want to prevent bubble
> > formation in the tissues at all depths, and in the blood deep.
> Off gassing
> > in bubble form into the blood is extremely efficient time wise
> and allows
> > faster decompressions that avoid building in one tissue while
> > eliminating in
> > another, but this is for non shunt people only. Unfortunately for the
> > shunts, the greatest incidence of bubbling into the venous blood occurs
> > after you get out of the water.
>
> From someone who doesn't come from the states - what's a shunt?
>
> /Jonas
>
> --
> Jonas Bergenudd
> +46 733 909 909
>
>
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: quest-unsubscribe@gu*.co*
> For additional commands, e-mail: quest-help@gu*.co*
>
>

--
Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.

Navigate by Author: [Previous] [Next] [Author Search Index]
Navigate by Subject: [Previous] [Next] [Subject Search Index]

[Send Reply] [Send Message with New Topic]

[Search Selection] [Mailing List Home] [Home]