Thoughts on in-water recompression

[Van Isle]

For those who do not know, a typical Table 6 treatment can be up to 6 hours long. At a SAC of .5 cuft/min one would need about 360 cu/ft of O2 at 30 feet. Depending on the severity depths may start at 60 feet on pure O2 thus requiring yet more gas. Obviously an injured diver could likely consume 4 times that amount. That's roughly 19 alu 80's of pure O2 at 3000 psi as gas for the injured diver only.

Even forgetting the risk of ox-tox and drowning, dehydration, hypothermia, etc, that's a fair amount of gas that has to make it down to the diver. And the treatment will only work if it's completed. And a bad bend can take SEVERAL table 6's over many days, plus hospital time, and dive physician supervision, to fix. Logistically that's a pretty hard thing to accomplish.

That's why the frequent and near-universal "do not attempt" caveat for IWR.

All numbers are approx and for illustrative purporses only. Do not attempt IWR at home or abroad. I may be a doctor, but not that kind. I'll have a look anyway ;-)

 

[Akimbo]

I don’t think anyone would choose in water treatment over a chamber ride. Just as nobody in their right mind would attempt a Table 6. At best, you would breath Oxygen at 20-25' for as long as you can handle it or until a better alternative is available.

 

[eponym]

From a post in last year's http://www.scubaboard.com/forums/as...9269-blow-n-go-emergency-ascent-question.html which was also about IWR and its inadvisability in most cases . . .

Scuba-doc.com has a powerpoint piece on accident management which recommends all of the following be available before attempting in-water recompression:
full-face mask
oxygen breathing system
adequate supplies of oxygen
cradle, chair or platform that can be lowered to the desired depth
warm, calm water without current and without dangerous marine animals

-Bryan

 

[muddiver]

The biggest issue with in water recompression is not the Oxtox or the gas alone. It is that you would probably go into hypothermia before the symptoms were releaved. Then you would run out of breathing gas.

 

[MikeMarlow]

Real simple answer. Call DAN, explain your situation (symptoms, location, and resources), follow their advice. For a good example of why, read "Rescue in the Gulf of Thailand" in the Fall 2009 issue of Alert Diver. IWR was attempted but immediately stopped due to worsening symptoms.

Mike

 

[Hatul]

The other issue: if the diver does decide to go back underwater, you need to have someone with him/her in close contact and be prepared to rescue, in case the symptoms get worse or runs into problems. This is not the time for solo diving.

Adam

 

[drbill]

I know of a very accomplished diver who tried this herself... and ended up a fatality. Wouldn't think of doing it myself.

 

[Rhone Man]

IWR can be a hot button topic. There are abundant stories of technical divers who have completed their deco schedule, come up, felt a few tweaks, and then gone back down with a bottle of O2 and breathing it for 20 minutes or so before resurfacing. If an experienced tec diver makes that call, then I'd back it. Similarly, last time I recall there being a thread about this on SB there was a discussion of a case of three divers somewhere in the Pacific who blew off a huge amount of deco for some reason - two tried IWR and one didn't. The two who got back in the water took a bad DCS hit, but survived; the guy who stayed dry died. I seem to recall it took nearly 48 hours to get to the nearest chamber.

What do these lessons tell you? Not much. Different situations, different divers, different equipment, different risks. Monday morning quarterbacks have the easier job than the guys responding to the emergency. But in certain specific circumstances, IWR has to be an option that some people may need to consider.

One thing we can all agree on is that prevention must be better than cure.

 

[TSandM]

One point that hasn't been made is that there is a HUGE difference between omitted decompression and treatment of a symptomatic diver. For omitted decompression, sure, I'd grab an O2 bottle and go back down and sit at 20 feet (hopefully with a watchful companion). Once symptoms have started, it's a whole different ball game.

Generally you aren't going to be remotely close to being all that bent and its going to be joint pain or skin bends.

Although I can't recall the reference, I recently read an analysis of accidents (may have been in the PADI magazine) where it turned out Type II hits were more common in recreational divers, often associated with excessively rapid ascents. This makes sense with the demographics of DCS, where it's more common in novice divers, who are unlikely (due to gas consumption) to be able to stay down long enough to acquire large nitrogen loads, but who ARE likely to have difficulties with buoyancy control, and who are (one hopes) more prone to panic than people with more experience.

 

[elmer fudd]

If I accidentally went into deco and missed a stop, or I came up way too fast, but was still asymptomatic, I think I'd be very inclined to grab another tank and head back down ASAP with the intent of making an hour long ascent from 60' or so. I don't think I'd have any problem urging another diver to do the same either. I imagine I'd probably go down with him as an observer.

If on the other hand one of us was really bent and exhibiting symptoms, then I think it would be the time to call for emergency assistance and get to a chamber.

When you get right down to it, IWR does the exact same thing as a chamber, only without the same controls, facilities or trained medical personnel. So I'd tend to view it like other self medical treatment. It's the kind of thing that's fine if things aren't too serious or it's your only option, but if you're really in trouble and the facilities are available you're foolish not to seek out the pros.