The subject was touched on . .
After TSHTF, what should have been the right decision?
They decided to try some recompression at 60-70fsw.
They could have gone to the chamber.
What should have been the right decision, and why? What was the time to travel to the chamber, and surely the risky in-water recompression could have done SOME good?
Jax, the hyperphobia against in-water recompression approaches that seen in the early days of Nitrox being "devil gas". Misunderstanding that's amplified by word-of-mouth telling, especially because the folks that have done it with great results don't want to be labeled as kooks or reckless or whatever.
The big split comes from the question: after surfacing, do you have symptoms? If the answer is No, then you have
Omitted Decompression. If yes, then it becomes
In-Water Recompression (IWR).
Omitted Decompression is generally defined as (A) symptom-free, and (B) you
know you missed stops, and (C) you can get back in the water quickly. There's several guidelines, but generaly it's re-enter the water within 1 to 5 minutes (depends on the text you're reading), complete all stops, and extend the 30'/20'/10' stops by 2x (or 1.5 times, again, depending on the textbook).
In-Water Recompression is used when symptoms appear after surfacing. Most reccomend this for dire situations in remote locations where a proper chamber is 12 hours or more away, or at least significantly delayed. There's at least 4 different variations I've seen, and all vary in depth used, gas selection, times, and profile.
IWR has it's risks - progression of symptoms while you are underwater is a worst case scenario - but, potential benefits, including arresting & shrinking bubbles as quickly as possible before tissue death occurs. Add to this the additional requirement of someone who is well trained in IWR, extra equipment such as a full face mask and tons of O2, and the exposure protection demands of extending the patient's time underwater, and you can see that IWR is not something you want to perform off the cuff. It has to be a thoughtful event with expert planning.
As a generality, IWR can vary from breathing 100% at 30' for 30 to 90 minutes, followed by a 2-hour ascent. Or, a popular method for divers in the Hawiian deep fish trade is descending to the depth that symptoms resolve, plus 30', then a slow ascent including O2. There's methods that are somewhat a blend in the middle, so to speak.
I am deliberately being obtuse on the methods here; if this is something you want to add to your skills, please, go take a complex deco class. ...It's worth pointing out there are some "big names" in the diving world that have availed themselves of IWR with a surprising success rate.
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I am not sure, but somewhere in this thread (or the other one) there was mention that the trio of divers was symptom free on initial surfacing, and it was only at the appearance of symptoms while underwater at 60' did they re-surface and run for the chamber.
If being symptom free, would
I have performed Omitted Deco? The quick answer would be yes, but for a 300' dive on air I would have been starting with omitted stops starting at 120', and if one of the deep pair, starting at 160'.
...Or would I? The chamber is reputed to be a "5 minute boat ride", but being in emergency services myself, I know how that time can be a wishfull estimate. If symptom free, and sure beyond a doubt that I would have the chamber door shut in 30 minutes, I would decline Omitted Deco and breathe 100% O2 enroute to the chamber. Otherwise, all you'd see of me would be my SMB.
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Anyway, hope this clears up some questions. You are not automatically, inexorably bent on surfacing.
All the best, James
