Descend to Decompress???

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Found it.

You're going to go to 60' on a Table 6 because pure O2 is available and in use. You're not going to use pure O2 during IWR because, like many have said, you'll tox and probably drown. Thus, a Table 6 is moot because it assumes that pure O2 is available. When pure O2 is NOT available (and, more importantly, the environment is not conducive to using pure O2), then a Table 3 is administered. What is a Table 3? It is a 21.5 hour ride from 165' on air.

So, in summary, for IWR to be effective, yes, you would have to hit a depth of 165' and plan on clearing your schedule for the next day.

Just so there's no confusion, what I'm talking about is the kind of situation where DCS is inevitable as the result of omitted deco, NOT a missed safety stop.
 
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What the agencies fail to mention, is that it normally takes 1 to 2 minutes for hypersaturation to occur... actual bubbling is DCS. If you had a sudden explosive ascent, by accident, and you were able to fix the cause of the inflation problem, whatever, in a few seconds at the surface, you could still easily have time to rocket back down to your previous depth, and do a very slow ascent with multiple stops....

Not all the agencies. I think in the TDI manuals it says that if you break your ceiling, but you are able to re-descend within about 3 minutes (I think, would have to look it up) you should do that rather than immediately seeking emergency treatment.

Actually 3 minutes is on the conservative side. Most supersaturation takes longer to kick in, but going back down is not something you want to do lightly. Not quite the same thing, but look at
THIS TABLE in relation to times for onset of DCS.

But once you are actually symptomatic, going back down (in-water recompression) really should only be done in dire emergencies when conventional treatment is impossible.


---------- Post added April 20th, 2012 at 02:39 PM ----------

One other thought I will throw in: I was reading a paper on the DAN technical diving conference, and it was talking about how the panelist asked the room how many technical divers had surfaced, felt some kind of onset, and so had jumped back in and gone down to 20 feet to breath pure O2 for another 10 minutes or so. The report indicated that a fairly large number of hands went up.

So, not strictly speaking IWR, but still...

Personally, I have never seen that or done that. But just relaying it as an interesting tidbit.
 
Found it.

You're going to go to 60' on a Table 6 because pure O2 is available and in use. You're not going to use pure O2 during IWR because, like many have said, you'll tox and probably drown. Thus, a Table 6 is moot because it assumes that pure O2 is available. When pure O2 is NOT available (and, more importantly, the environment is not conducive to using pure O2), then a Table 3 is administered. What is a Table 3? It is a 21.5 hour ride from 165' on air.

So, in summary, for IWR to be effective, yes, you would have to hit a depth of 165' and plan on clearing your schedule for the next day.

Just so there's no confusion, what I'm talking about is the kind of situation where DCS is inevitable as the result of omitted deco, NOT a missed safety stop.

Bad advice. ONLY the Hawaiian method calls for a descent to 165 feet, or resolution of symptoms plus 30 feet. Of the few folks I know of that have real stories about the Hawaiian method, it is more often fatal than successful. Then get your happy butt to shallow water and go on 100% O2. The Clipperton rebreather method calls for depths greater than 30 feet, and then only to 98 feet for a short time.

A Table 3 is NOT an approved IWR method. The only Navy IWR methods are limited to 30 feet on 100% without air breaks. ALL approved IWR methods are conducted using 100% O2 except for the Clipperton rebreather method which is carried out at a PO2 of 1.4. Do not attempt IWR without 100% O2 for the diver. If 100% O2 cannot be supplied through a full face mask, do not attempt IWR.
 
My instructor answered this as follows:
- if you have access to EMS and the chamber in reasonable proximity call EMS so they can take you to the chamber.
- if the chamber is thousand miles away then do the in water recompression with the highest o2 gas available as long as you can but having someone going down with you to watch you.
I will do it if the condition is serious. What is the alternative?
A full face mask would be an added bonus but it is not a standard equipment on liveaboard or dive operator.
 
I am sure this has been covered on here before but I couldn't seem to find it, I was sitting back thinking about if for some crazy reason you shot up from the bottom and you were fairly deep and had been down close to your time limit at certain depth.

It's called in-water re-compression, and it should only be considered as a solution if the other option is "yer gonna die."

The problems include hypothermia, drowning from underwater seizures from 100% O2, sending bubbles into your brain (bubble pumping), drowning from running out of gas before it's safe to ascend, and a bunch of other stuff I don't remember anymore.

It's a "possibility", just not a good one if you have any other options.

flots.
 
Pete, I would agree with you, except for the bonafide "good diver" rapid accident ascent scenario I described above......in this scenario, you could prevent all damage of DCS from occurring....waiting for the chamber WILL GUARANTEE some damage, even if it is damage that can heal. Another scenario for this....you are on a deep ( 140 foot dive) and find a diver from another group from your boat, lying on the bottom unconscious--you have been down 10 minutes or more already. If you know the boat is likely to be near overhead, follwing your group's flag or buoy, then you"could" do a rapid ascent with the unconscious diver, inflate their BC as you near surface, SEE that the boat sees you and the EMERGENCY in the 10 seconds you are at the surface, then leave the diver on their back at surface ( hopefully with reg in mouth) and head straight back down--let the boat take over the rescue....With some boats and crews in Palm Beach, this would be a perfect rescue-- they would see you and be on you in seconds...and a crew member would be doing the cpr etc long before you could have done any thing due to being geared up.

We are talking very specific instances here....But the understanding of the issue of DCS does call for making real distinctions like this...and what moral responsibilities exist.
I don't dispute that there are some circumstances where IW Deco can work out. However the rank and file recreational diver probably can't make those distinctions especially in a stress situation. I read the OP's question as wanting to understand why IW deco wasn't a common remedy and offered some of the downsides. My last statement (post #6) does leave the door open for unique circumstances.
Pete
 
It's called in-water re-compression, and it should only be considered as a solution if the other option is "yer gonna die."

The problems include hypothermia, drowning from underwater seizures from 100% O2, sending bubbles into your brain (bubble pumping), drowning from running out of gas before it's safe to ascend, and a bunch of other stuff I don't remember anymore.

For those who don't know much about IWR (that includes me), it seemed useful to highlight one of the issues flots mentioned that's been pointed out in other threads on the topic. Remember that rides in hyperbaric chambers to treat DCS normally take many hours, and as mentioned above, stopping prematurely could make things worse than not starting at all. Given that, IWR plans have to include (as flots mentioned or suggested) many tanks of gas, staying warm for the whole time, staying monitored by someone else the whole time, and staying hydrated and fed, among other things. In other words, not something done casually and without lots of knowledge and planning, even in a perceived emergency.
 
IWR isn't important for almost anyone to know the procedures of, kind of like the procedures for saturation diving. 99.999% of all divers will never need to know the first thing about IWR, because they will never find themselves in a position to conduct it. I'll bet there are fewer than 5 boats on the planet that do the kind of diving where IWR might be required that don't have at least a hyperlite onboard.
 
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