It is actually true that to first order the amount of gas dissolved in
blood (with the exception of oxygen since it's subject to the
hemoglobin dissociation curve -- sort of an s shaped curve) is
proportional to the absolute pressure of the gas. The size of the
bubble that results from the serum's outgassing would depend first on
the difference in absolute pressure (that would tell you the mass of
gas that might no longer be in solution) and then on the ambient
pressure, since if the pressure was lower the bubble would expand
according to the gas laws (inversely proportional to pressure,
temperature is pretty fixed in the body. So, going from 34 feet deep
to the surface in water is a change of about one atmosphere. Going
from ground level to 18000 feet is a change of about a half an
atmosphere. The diver coming up from 34 feet would have twice the
potential mass of gas coming out of solution as would someone who went
from 0 to 18000 feet as suddenly.

It would, instead be like a diver coming up quickly after being at
17 feet deep. 0 to 18000 feet would be more or less the same as going
from a 7000 foot cabin pressure to one at 34000 feet. The pressure in
atmospheres is something like e^(-.034 A) where A is the altitude in
thousands of feet.

All of this is back of the envelope stuff done during a coffee break
so it could be very wrong. If 'feels' reasonable, though. I think
people die from explosive decompresssion because they don't get
oxygen, not from the bends.


. EURO On Nov 26, 1:09 pm, "Friedrich Ostertag"
wrote:
Stefan wrote:
george schrieb:

Point out to me where I am wrong...

Your mistake is, that the quantity of gas which can be solved in water
is proportional to pressure. So you mustn't think in absolute
quantities, but in relative.

what I was thinking, but better explained, thanks.

regards,
Friedrich