DevonDiver
N/A
Nor would 99.9999% of divers...ever need to take action in the Missed deco(safety stop)/fast ascent theory. I've seen the results a million times (or maybe a couple of thousand) and never been able to attribute any of the 200 or so cases of the bends I've seen during recreational diving to missed deco(safety stop)/fast ascent. Nor could I point my finger at a missed deco(safety stop)/fast ascent to a case of the bends. The point really is moot.....
Which nicely addresses the OP's initial questions
There is never a reason (IMHO) to re-descent following a recreational dive unless the diver is symptomatic,
I think that's the debate that the OP wanted. Whether re-descent could prevent (as opposed to treat) DCS.
IMHO, I agree with you - I don't see a benefit for re-descending, given the tolerances in recreational dive planning/management.
I also believe that re-descent would be unlikely to resolve any bubble formation, which may have occurred on the fast ascent. At the worst, I believe it'd contribute to bubble growth and potential migration, rather than reduction. My layman's understanding/assumption is.....
In a nutshell, rapid and sustained ascent can caused bubble formation. In most instances, on recreational dives, those bubbles are likely to remain non-symptomatic - therefore, not a problem. Re-descending will shrink those bubbles, due to ambient pressure, not through dissipation. Off-gassing only occurs as pressure is reduced, not increased. Increased depth adds pressure inside the given volume of the bubbles, causing them to grow larger when the diver eventually ascends. Once shrunken, it they pass more easily through tissues into body tissues and systems they wouldn't otherwise be able to reach - bubbles may meet and coalesce - forming bigger bubbles. The combination of increased bubble volume through extended on-gassing, and the risk of bubble migration/coalescing increases risk to the diver that otherwise non-symptomatic bubbles could develop into symptomatic ones.
In contrast, aborting the dive after a fast ascent, and conducting a protracted ascent pause at safety stop depth will temporarily halt bubble expansion, whilst providing the necessary pressure differential to begin off-gassing and bubble dissipation. Meaning smaller bubbles.
That said, I've never heard any educated reasoning which explored the specific concept. I'd certainly be interested in hearing a deco nerd explanation of why it'd be beneficial/pointless.
...then there is not a reason to re-descend, treat the diver accordingly. Modern computers will not clear following a rapid ascent or surfacing in deco by descending.
Absolutely. There is very clear guidance on DCS first-aid treatment and protocols. In virtually any instance effecting a recreational diver that guidance is completely sound. The same is true for virtually every tech diver - for whom only a very rare combination of circumstances would necessitate ad-hoc IWR as being preferable to first-aid and evacuation.
So, in answering the OP's question, we find that there is never a reason to descend following a recreational dive. Unless you're ready to dive again.