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>> Taken from a friend's post on another board:
>>
[quoted text clipped - 13 lines]
> things. Anyway, i haven't read the article... is the one case given
> the only data?
Another case of PADI standards gone awry...
> Aren't the flying after diving rules based on the assumption of a
> minimum cabin pressure equivalent to something like 8,000 ft? I might
> guess flying in an unpressurized cabin above that level would change
> things. Anyway, i haven't read the article... is the one case given
> the only data?
The following is copied from a followup post:
"Here is the article
You've just finished a great dive trip in the Solomon Islands and now you're
preparing for the four back-toback flights needed to reach home. Think twice
before you get on board -- the recommended 24-hour waiting period after your
last dive may not be enough.
"The problem of flying after diving goes way back, but the issue of
repetitive flying has not been talked about much at all," says Frederick S.
Cramer, M.D., director of the San Francisco Institute for Hyperbaric
Medicine. He presented a study about the effects of repetitive post-dive
flights at the Undersea Hyberbaric Medical Society conference last summer.
Ascending to altitude means a decrease in pressure, causing the nitrogen
that built up in a diver's blood and plasma underwater to come out of those
solutions and start bubbling. After touching down at sea level, the bubbles
will get smaller but they won't go down to predive levels right away because
there is still surface tension between the bubbles' exterior and the
surrounding liquid. Multiple flights in one day after no-decompression dives
means the bubbles will keep growing, Cramer says. "Say a bubble measures
one-eighth of an inch before you fly. You go up to 10,000 feet and it grows
to one-half inch. You come back down to the surface, but it only goes back
down to one-quarter inch, so it's not back to normal for a while. If you're
flying repetitively in a short timespan--and you keep going to higher
altitudes-- those bubbles will keep getting bigger."
At the conference, Cramer presented a case study of a 37-year-old female
diver from Couer d'Alene, Idaho. After 10 dives in the Caymans over six days
with a 30- hour delay before flying, she began a four-leg trip back home.
She flew in an unpressurized inter-island plane that rose to 5,000 feet and
landed in Grand Cayman, situated at sea level. The second plane rose to
35,000 feet, maintaining cabin pressure at 8,000 feet, and landed at Miami,
again at sea level. The third plane also flew to the same levels as the
second but landed at Minneapolis, 1,000 feet above sea level.
That's when she noticed "skin bends," or nitrogen bubbles crawling like
worms under the skin of her abdominal area. "That's an early warning sign
that the nitrogen bubbles are starting to come out of solution," says
Cramer. But the woman, herself a physician, chose to ignore the signs and
boarded her fourth flight to Spokane, at an elevation of 2,400 above sea
level. She arrived with a dull pain in her right shoulder, another major
warning sign she again chose to ignore, so she could drive home to sleep.
Four hours later, at 2 a.m., she woke up with stronger shoulder pain,
shortness of breath, chest pain and acute anxiety. She went to her local ER,
and the attending physician, also a scuba diver, realized she was suffering
from serious decompression sickness and got her into an hyperbaric chamber.
After 285 minutes of treatment, the woman exited with all DCI symptoms gone.
"But if she had canceled her flight to Spokane, stayed overnight at a
airport hotel and had some aspirin and rest, this wouldn't have happened,"
says Cramer. "Early diagnosis is treatable but if ignored it can be fatal."
Even though you may have waited 24 hours after your last dive, frequently
going up and down in airplanes is dangerous because of the continuous bubble
growth in your bloodstream. Going to a progressively higher altitude is
worse. If you experience skin bends or headaches, stay off the plane.
Consider breaking up your trips by staying overnight halfway through, and
keep a constant watch for symptoms."
Paul Foley - 24 Mar 2007 12:58 GMT
> She flew in an unpressurized inter-island plane that rose to 5,000 feet and
> landed in Grand Cayman, situated at sea level. The second plane rose to
> 35,000 feet, maintaining cabin pressure at 8,000 feet, and landed at Miami,
> again at sea level. The third plane also flew to the same levels as the
> second but landed at Minneapolis, 1,000 feet above sea level.
How do we know these planes are really pressurized to 8000'? Maybe
those cheap bastards who run the airlines are cutting back on the cabin
pressure the way they've cut back on the free peanuts.
I'm bringing an altimeter with me next time I fly.
Douglas W "Popeye" Frederick - 24 Mar 2007 21:44 GMT
>> She flew in an unpressurized inter-island plane that rose to 5,000 feet
>> and
[quoted text clipped - 9 lines]
>
> I'm bringing an altimeter with me next time I fly.
<Cough>
William Dryden - 30 Mar 2007 02:05 GMT
> >> She flew in an unpressurized inter-island plane that rose to 5,000 feet
> >> and
[quoted text clipped - 11 lines]
>
> <Cough>
I initialized an Edge at altitude coming back from Mexico once. When I
landed in Houston, TX the Edge said I was nine feet under water.
Grumman-581 - 30 Mar 2007 02:24 GMT
> I initialized an Edge at altitude coming back from Mexico once. When I
> landed in Houston, TX the Edge said I was nine feet under water.
That wouldn't have been during Allison, perhaps? If so, it was probably
accurate...
William Dryden - 30 Mar 2007 04:44 GMT
> > I initialized an Edge at altitude coming back from Mexico once. When I
> > landed in Houston, TX the Edge said I was nine feet under water.
>
> That wouldn't have been during Allison, perhaps? If so, it was probably
> accurate...
Nope - It was a long time before Allison. I was trying to see if it would
register anything for the difference in air pressure. If you take the 8000
ft cabin pressure as true, the difference in air pressure from 8000 ft and
100 ft (IAH) is the same as surface to 9 ft under water.