So why is it a bad idea to go back to do a safety stop if you blow it?

[boulderjohn]

There's more than a "few" problems with attempting in-water re-compression. In fact, there are so many potential problems and drawbacks that in-water re-compression is simply not a viable option unless a considerable amount of logistical and medical planning/preparation has been conducted in advance. It is a majorundertaking, well beyond the capabilities of any recreational dive charter. If a technical charter/expedition wished to provide re-compression, it'd probably be simpler and more effective to just get a portable hyperbaric chamber on their vessel.

There are already some very informative threads on this subject already. However, as a very basic run-down; here are some considerations:

1) In-water re-compression typically takes many hours
2) The casualty needs to be delivered with pure O2
3) The casualty needs to be rapidly hydrated
4) The casualty needs medications (immuno-suppressants, anti-inflammatories etc)
5) The casualty needs treatment for shock and/or may lose consciousness
6) The casualty needs continual monitoring, including neurological assessments
7) The casualty needs to be maintained at an optimal temperature

...the list goes on.

While I agree that In-water recompression is not something that should be taken lightly and needs knowledge and advanced preparation, I am not sure that the needs are necessarily so drastic. This Wikipedia article describes some IWR protocols that do not last an hour, let alone many hours.

http://en.wikipedia.org/wiki/In-water_recompression

I have done a lot of diving with a group that does deep diving in a sinkhole on the prairie of New Mexico. They have no good facilities nearby, and a chamber is a long haul away. They keep an O2 tank and a full face mask on site for this purpose. They have done 3 IWRs that I know of. I know each of the people who were recompressed this way, but I was not present on any of the occasions. I don't believe any of the treatments lasted more than a half hour, although I could be wrong. All 3 were successfully resolved.

 

[UCFKnightDiver]

If you have DCS in-water recompression has many hazards and if you don't have DCS there is no need to go back in the water. A better idea is: Don't skip safety stops from below 100 feet and don't shoot up like a polaris missile ever.

The onset for DCS symptoms is not always immediate.