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Continuing this discussion:
Charles V. Brown, M.D. in "The Physiology of Decompression Sickness,"
discusses how osmotic pressure plays a role in decompression. Namely this
relates to, and I quote:

"...the tendency of water to flow (along its own concentration gradient)
from areas where the concentration of dissolved materials is low to where
it is high. During ascent, fast tissues lose gas more rapidly than slow
tissues, and the resulting osmotic gradients would tend to pull water from
the fast to the slow tissues. A special case is blood, which is thought to
equilibrate with tissues by the time it traverses capillaries. In the
arterial portion of the capillary, up to where equilibrium is reached,
blood would lose water to the tissue. Hemoconcentration favors
decompression sickness.

Osmotic gradients created by the DESCENT phase of the dive could also be
significant. Dissolved gas in working muscle and in the bone marrow would
rise much faster than in the adjacent bone cortex, tending to dehydrate it.
Hemoconcentration in the cortex capillaries would favor red cell sludging
and blood clotting, and thus osteonecrosis. If this is significant, as
animal studies suggest if may be, dysbaric osteonecrosis becomes, to the
extent, compression sickness." (end quote)

Something to consider for descent rates. I haven't done any significant
research into other sources on this subject, but there are possibilities
that rapid descent rates may have long term affects on the bone structure.
Now what is defined as rapid descents? 

Take care,
Doug


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