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>...As I told somebody else today, one of the discoveries >of commercial diving is that too rapid compression is a >major problem in the joints and bones.... On a rapid compression (descent), asymmetric gas concentration between the bone cortex and the neighboring muscle and marrow may cause osmotic gradients between bone cortex, and the marrow and muscle leading to dehydration of the bone cortex. The resulting hemoconcentration in the cortex may lead to red cell sluding and blood clotting and therfore dysbaric bone osteonecrosis [1]. Commercial practice usually entails a relatively slow compression (and decompression), perhaps for several reasons, but bone necrosis appears to be a major concern. One may argue the total duration of compression is a factor, and I suspect it is, but all that aside it appears that a rapid compression is not good. The human body has an amazing ability to physiologically respond to stimuli very rapidly and I suspect (although I do not know for certain) the processes experienced by commercial divers are at work, although somewhat reduced, in technical diving events such as descent. A good boat operator can drop you in a current to give a reasonable descent time to the bottom. IMHO. References: [1] "The Physiology of Decompression Sickness," Charles V. Brown, M.D., 1979. Take care, Doug -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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